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HESI Chemistry _ All you need to pass the test
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HESI Chemistry Questions, Answers, and Explanations
HESI Chemistry Questions with Answers and Explanations 1. Which of the following substances allows for the fastest diffusion? A. gas B. solid C... [Show More] . liquid D. plasma Explanation: Diffusion is fastest through gases. The next fastest medium for diffusion is liquid, followed by plasma, and then solids. In chemistry, diffusion is defined as the movement of matter by the random motions of molecules. In a gas or a liquid, the molecules are in perpetual motion. For instance, in a quantity of seemingly immobile air, molecules of nitrogen and oxygen are constantly bouncing off each other. There is even some miniscule degree of diffusion in solids, which rises in proportion to the temperature of the substance. 2. What is the oxidation number of hydrogen in CaH2? A. +1 B. 1 C. 0 D. +2 Explanation: The oxidation number of the hydrogen in CaH2 is –1. The oxidation number is the positive or negative charge of a monoatomic ion. In other words, the oxidation number is the numerical charge on an ion. An ion is a charged version of an element. Oxidation number is often referred to as oxidation state. Oxidation number is sometimes used to describe the number of electrons that must be added or removed from an atom in order to convert the atom to its elemental form. 3. Which of the following does not exist as a diatomic molecule? A. boron B. fluorine C. oxygen D. nitrogen Explanation: Boron does not exist as a diatomic molecule. The other possible answer choices, fluorine, oxygen, and nitrogen, all exist as diatomic molecules. A diatomic molecule always appears in nature as a pair: The word diatomic means “having two atoms.” With the exception of astatine, all of the halogens are diatomic. Chemistry students often use the mnemonic BrINClHOF (pronounced “brinkelhoff”) to remember all of the diatomic elements: bromine, iodine, nitrogen, chlorine, hydrogen, oxygen, and fluorine. Note that not all of these diatomic elements are halogens. 4. What is another name for aqueous HI? A. hydroiodate acid B. hydrogen monoiodide C. hydrogen iodide D. hydriodic acid Explanation: Hydriodic acid is another name for aqueous HI. In an aqueous solution, the solvent is water. Hydriodic acid is a polyatomic ion, meaning that it is composed of two or more elements. When this solution has an increased amount of oxygen, the -ate suffix on the first word is converted to -ic. The HESI exam will require you to know the fundamentals of naming chemicals. This process can be quite complex, so you should carefully review this material before your exam. 5. Which of the following could be an empirical formula? A. C4H8 B. C2H6 C. CH D. C3H6 Explanation: CH could be an empirical formula. An empirical formula is the smallest expression of a chemical formula. To be empirical, a formula must be incapable of being reduced. For this reason, answer choices A, B, and D are incorrect, as they could all be reduced to a simpler form. Note that empirical formulas are not the same as compounds, which do not have to be irreducible. Two compounds can have the same empirical formula but different molecular formulas. The molecular formula is the actual number of atoms in the molecule. 6. What is the name for the reactant that is entirely consumed by the reaction? A. limiting reactant B. reducing agent C. reaction intermediate D. reagent Explanation: A limiting reactant is entirely used up by the chemical reaction. Limiting reactants control the extent of the reaction and determine the quantity of the product. A reducing agent is a substance that reduces the amount of another substance by losing electrons. A reagent is any substance used in a chemical reaction. Some of the most common reagents in the laboratory are sodium hydroxide and hydrochloric acid. The behavior and properties of these substances are known, so they can be effectively used to produce predictable reactions in an experiment. 7. What is the name for the horizontal rows of the periodic table? A. groups B. periods C. families D. sets Explanation: The horizontal rows of the periodic table are called periods. The vertical columns of the periodic table are known as groups or families. All of the elements in a group have similar properties. The relationships between the elements in each period are similar as you move from left to right. The periodic table was developed by Dmitri Mendeleev to organize the known elements according to their similarities. New elements can be added to the periodic table without necessitating a redesign. 8. What is the mass (in grams) of 7.35 mol water? A. 10.7 g B. 18 g C. 132 g D. 180.6 g Explanation: The mass of 7.35 mol water is 132 grams. You should be able to find the mass of various chemical compounds when you are given the number of mols. The information required to perform this function is included on the periodic table. To solve this problem, find the molecular mass of water by finding the respective weights of hydrogen and oxygen. Remember that water contains two hydrogen molecules and one oxygen molecule. The molecular mass of hydrogen is roughly 1, and the molecular mass of oxygen is roughly 16. A molecule of water, then, has approximately 18 grams of mass. Multiply this by 7.35 mol, and you will obtain the answer 132.3, which is closest to answer choice C. 9. Which of the following orbitals is the last to fill? A. 1s B. 3s C. 4p D. 6s Explanation: Of these orbitals, the last to fill is 6s. Orbitals fill in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, and 7p. The number is the orbital number, and the letter is the sublevel identification. Sublevel s has one orbital and can hold a maximum of two electrons. Sublevel p has three orbitals and can hold a maximum of six electrons. Sublevel d has five orbitals and can hold a maximum of 10 electrons. Sublevel f has seven orbitals and can hold a maximum of 14 electrons. 10. What is the name of the binary molecular compound NO5? A. nitro pentoxide B. ammonium pentoxide C. nitrogen pentoxide D. pentnitrogen oxide Explanation: Nitrogen pentoxide is the name of the binary molecular compound NO5. The format given in answer choice C is appropriate when dealing with two nonmetals. A prefix is used to denote the number of atoms of each element. Note that when there are seven atoms of a given element, the prefix hepta- is used instead of the usual septa-. Also, when the first atom in this kind of binary molecular compound is single, it does not need to be given the prefix mono-. 11. What is the mass (in grams) of 1.0 mol oxygen gas? A. 12 g B. 16 g C. 28 g D. 32 g Explanation: The mass of 1.0 mol oxygen gas is 32 grams. The molar mass of oxygen can be obtained from the periodic table. In most versions of the table, the molar mass of the element is directly beneath the full name of the element. There is a little trick to this question. Oxygen is a diatomic molecule, which means that it always appears in pairs. In order to determine the mass in grams of 1.0 mol of oxygen gas, then, you must double the molar mass. The listed mass is 16, so the correct answer to the problem is 32. 12. Which kind of radiation has no charge? A. beta B. alpha C. delta D. gamma Explanation: Gamma radiation has no charge. This form of electromagnetic radiation can travel a long distance and can penetrate the human body. Sunlight and radio waves are both examples of gamma radiation. Alpha radiation has a 2+ charge. It only travels short distances and cannot penetrate clothing or skin. Radium and uranium both emit alpha radiation. Beta radiation has a 1– charge. It can travel several feet through the air and is capable of penetrating the skin. This kind of radiation can be damaging to health over a long period of exposure. There is no such thing as delta radiation. 13. What is the name of the state in which forward and reverse chemical reactions are occurring at the same rate? A. equilibrium B. constancy C. stability D. toxicity Explanation: When forward and reverse chemical reactions are taking place at the same rate, a chemical reaction has achieved equilibrium. This means that the respective concentrations of reactants and products do not change over time. In theory, a chemical reaction will remain in equilibrium indefinitely. One of the common tasks in the chemistry lab is to find the equilibrium constant (or set of relative concentrations that result in equilibrium) for a given reaction. In thermal equilibrium, there is no net heat exchange between a body and its surroundings. In dynamic equilibrium, any motion in one direction is offset by an equal motion in the other direction. 14. What is 119°K in degrees Celsius? A. 32°C B. –154°C C. 154°C D. –32°C Explanation: 119°K is equivalent to –154 degrees Celsius. It is likely that you will have to perform at least one temperature conversion on the HESI exam. To convert degrees Kelvin to degrees Celsius, simply subtract 273. To convert degrees Celsius to degrees Kelvin, simply add 273. To convert degrees Kelvin into degrees Fahrenheit, multiply by 9/5 and subtract 460. To convert degrees Fahrenheit to degrees Kelvin, add 460 and then multiply by 5/9. To convert degrees Celsius to degrees Fahrenheit, multiply by 9/5 and then add 32. To convert degrees Fahrenheit to degrees Celsius, subtract 32 and then multiply by 5/9. 15. What is the SI unit of energy? A. ohm B. joule C. henry D. newton Explanation: The joule is the SI unit of energy. Energy is the ability to do work or generate heat. In regard to electrical energy, a joule is the amount of electrical energy required to pass a current of one ampere through a resistance of one ohm for one second. In physical or mechanical terms, the joule is the amount of energy required for a force of one newton to act over a distance of one meter. The ohm is a unit of electrical resistance. The henry is a unit of inductance. The newton is a unit of force. 16. What is the name of the device that separates gaseous ions by their mass-to-charge ratio? A. mass spectrometer B. interferometer C. magnetometer D. capacitance meter Explanation: A mass spectrometer separates gaseous ions according to their mass-to-charge ratio. This machine is used to distinguish the various elements in a piece of matter. An interferometer measures the wavelength of light by comparing the interference phenomena of two waves: an experimental wave and a reference wave. A magnetometer measures the direction and magnitude of a magnetic field. Finally, a capacitance meter measures the capacitance of a capacitor. Some sophisticated capacitance meters may also measure inductance, leakage, and equivalent series resistance. 17. Which material has the smallest specific heat? A. water B. wood C. aluminum D. glass Explanation: Of the given materials, aluminum has the smallest specific heat. The specific heat of a substance is the amount of heat required to raise the temperature of one gram of the substance by one degree Celsius. In some cases, specific heat is expressed as a ratio of the heat required to raise the temperature of one gram of a substance by one degree Celsius to the heat required to raise the temperature of one gram of water by one degree Celsius. 18. What is the name for a reaction in which electrons are transferred from one atom to another? A. combustion reaction B. synthesis reaction C. redox reaction D. double-displacement reaction Explanation: In a redox reaction, also known as an oxidation-reduction reaction, electrons are transferred from one atom to another. A redox reaction changes the oxidation numbers of the atoms. In a combustion reaction, one material combines with an oxidizer to form a product and generate heat. In a synthesis reaction, multiple chemicals are combined to create a more complex product. In a double-displacement reaction, two chemical compounds trade bonds or ions and create two different compounds. Other common chemical reactions you may need to know for the HESI exam are the acid-base reaction, analysis reaction, single-displacement reaction, isomerization reaction, and hydrolysis reaction. 19. What are van der Waals forces? A. the weak forces of attraction between two molecules B. the strong forces of attraction between two molecules C. hydrogen bonds D. conjugal bonds Explanation: van der Waals forces are the weak forces of attraction between two molecules. The van der Waals force is considered to be any of the attractive or repulsive forces between electrons that are not related to electrostatic interaction or covalent bonds. Compared to other chemical bonds, the strength of van der Waals forces is small. However, these forces have a great effect on a substance’s solubility and other characteristics. The HESI exam may require you to demonstrate knowledge of all the major chemical forces. 20. Which of the following gases effuses the fastest? A. Cl2 B. O2 C. N2 D. H2 Explanation: Of the given gases, H2 effuses the fastest. It has the smallest molecular weight, and it is therefore capable of moving faster than the molecules represented by the other answer choices. In chemistry, effusion is defined as the flow of a gas through a small opening. The rate of effusion of a substance is inversely proportional to the square root of the density of the substance. This means that the less dense a substance is, the faster it will effuse. This agrees with the common observation that thick smoke tends to linger in the same form for a longer period than thin smoke or steam. 21. Which of the following elements is not involved in many hydrogen bonds? A. fluorine B. carbon C. oxygen D. nitrogen Explanation: Carbon is not involved in many hydrogen bonds. A hydrogen bond occurs when an atom of hydrogen that has a covalent bond with an electronegative atom forms a bond with a third atom. The original covalent bond involving hydrogen gives away protons, and the third element receives them. One of the reasons that fluorine, oxygen, and nitrogen are frequently part of a hydrogen bond is that they have a strong electronegativity and are therefore able to form more durable bonds. Chlorine is another element frequently involved in hydrogen bonds. 22. What is the mass (in grams) of 0.350 mol copper? A. 12.5 g B. 14.6 g C. 18.5 g D. 22.2 g Explanation: The mass of 0.350 mol copper is 22.2 grams. This problem requires the use of the periodic table. There you will see that the molecular mass of copper is approximately 63.5. Take this figure and multiply it by the amount of copper given by the question: 0.350 mol. The resulting figure is 22.225, which, rounded to the nearest tenth, is 22.2 grams. In order to succeed on the HESI exam, you will need to be able to perform these simple calculations of mass. 23. How many d orbitals are there in a d subshell? A. 5 B. 7 C. 9 D. 11 Explanation: There are five d orbitals in a d subshell (or sublevel). Each of these orbitals can hold two electrons, so sublevel d is capable of holding 10 electrons. The s subshell has one orbital, the p subshell has three orbitals, the d subshell has five orbitals, and the f subshell has seven orbitals. In chemistry, the electron configuration of an atom is expressed in the following form, using helium as an example: 1s2. In this notation, the 1 indicates that the electrons are found in the first energy level of the atom, the s indicates that the electrons are in a spherical orbit, and the superscript 2 indicates that there are 2 total electrons in the first energy level subshell. 24. What is the name for the number of protons in an atom? A. atomic identity B. atomic mass C. atomic weight D. atomic number Explanation: The number of protons in an atom is the atomic number. Protons are the fundamental positive unit of an atom. They are located in the nucleus. In a neutral atom (an atom with neither positive nor negative charge), the number of protons in the nucleus is equal to the number of electrons orbiting the nucleus. When it needs to be expressed, atomic number is written as a subscript in front of the element’s symbol, for example in 13Al. Atomic mass, meanwhile, is the average mass of the various isotopes of a given element. Atomic identity and atomic weight are not concepts in chemistry. 25. Which of the following elements is an alkali metal? A. magnesium B. rubidium C. hydrogen D. chlorine Explanation: Rubidium is an alkali metal. The alkali metals are located in group 1 of the periodic table. These soft substances melt at a low temperature and are typically white in color. The alkali metals are lithium, sodium, potassium, rubidium, cesium, and francium. Rubidium, cesium, and francium are not commonly encountered in the natural world. The alkali metals are highly reactive, meaning that they easily engage in chemical reactions when combined with other elements. These metals have a low density and tend to react violently with water. [Show Less]
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HESI Chemistry Questions and Answers
HESI Chemistry Chemistry Practice Test 1. What are all metric measurements composed of? A. Metric prefix and a basic unit of measure B. A significa... [Show More] nd and a metric prefix C. A metric prefix and a coefficient D. A coefficient and a significand 2. What is the most commonly used temperature scale in the scientific community? A. Fahrenheit B. Celsius or Centigrade C. Kelvin D. English temperature method 3. The nucleus of an atom contains or is made up of which of the following? A. Protons and electrons B. Protons only C. Protons and neutrons D. Neutrons and electrons 4. What is an atom that has a positive charge called? A. A cathode B. A cation C. An anode D. An anion 5. In the periodic table, what are the rows called? A. Groups B. Moles C. Columns D. Periods 6. What is the atomic number? A. Number of neutrons B. Number of protons C. Number of electrons D. Number of isotopes 7. Which of the following describes the atomic mass? A. Mass of protons and electrons B. Mass of neutrons and electrons C. Average mass of that element’s isotopes D. Number of moles in a solution 8. Chemical equations are written in which manner? A. Product → Reactants B. Reactants → Products C. Reactants + Reactants D. Products + Reactants 9. What is the charge on potassium in the compound KCl? A. −1 B. +1 C. −2 D. +2 10. A catalyst is a substance that accelerates a reaction by which of the following? A. Adding energy to the overall reaction B. Increasing the amount of energy needed for the reaction to occur C. Finding an alternate pathway for a reaction that requires less energy D. Speeding up the overall reaction process 11. Percent concentration of a solution is expressed as which of the following? A. 100 parts per 100 dL B. Parts per 100 parts C. Parts of moles D. Moles per 100 parts 12. What will one liter of a one molar solution of any element contain? A. The atomic mass in grams of that element B. The atomic number in grams of that element C. The atomic mass in liters of that element D. The atomic number in liters of that element 13. Chemical bonding is the bonding of which of the following? A. One atom to another atom B. One mole to another mole C. A proton to an electron D. One cation to another cation 14. Which of the following describes an ionic bond? A. It shares electrons. B. It does not share electrons. C. It is sometimes called a covalent bond. D. It is the strongest of all chemical bonds. 15. The reaction 2C2H6 + 7O2 → 4CO2 + 6H2O has a ratio of 2 parts ethane (C2H6) and 7 parts oxygen (O2). How many parts of ethane (C2H6) will be needed to react with 21 parts of oxygen (O2)? A. 3 parts of ethane C2H6 B. 6 parts of ethane C2H6 C. 9 parts of ethane C2H6 D. 14 parts of ethane C2H6 16. What is the concentration of 58.5 g of NaCl in 2 L of solution (atomic weights of each element are as follows: Na = 23 g/mol, Cl = 35.5 g/mol)? A. 0.5 mol NaCl B. 0.75 mol NaCl C. 1 mol NaCl D. 2 mol NaCl 17. In a redox reaction, which of the following describes reduction? A. It is the loss of electrons. B. It is the gain of protons. C. It is the loss of a neutron. D. It is the gain of electrons. 18. What are acids? A. Hydrogen acceptors B. Solutions of high pH C. Hydrogen donors D. Amphoteric 19. What is a benefit of water’s ability to make hydrogen bonds? A. Lack of cohesiveness B. Low surface tension C. Use as a nonpolar solvent D. High specific heat 20. What are bases or alkaline solutions? A. Hydrogen acceptors B. Solutions of low pH C. Hydrogen donors D. Amphoteric 21. Chemical reactions in living systems proceed along catabolic pathways, and there tends to be an increase in which of the following? A. Entropy B. Enthalpy C. Glucose D. Glycogen 22. What is a pH of 7? A. Acidic B. Basic C. Neutral D. Positive 23. Which is the correct way to write Iodine (I) with an atomic mass of 131? A. I131 B. I131 C. 131I D. 24. 131I What is the correct formula for magnesium chloride? A. MgCl2 B. MgCl C. Mg2Cl D. Mg2Cl2 25. What is the weakest of all the intermolecular forces? A. Dispersion B. Dipole interactions C. Hydrogen bonding D. Covalent bonding 26. Beta radiation is the emission of which of the following? A. Large numbers of helium ions B. An electron C. High energy electromagnetic radiation D. A product of the decomposition of a proton 27. Which of the following describes carbohydrates? A. They serve as fuel for the body. B. They are present in DNA but not in RNA. C. They are the least abundant biomolecule. D. They cannot be stored in the body. 28. What are monosaccharides? A. The simplest form of carbohydrates B. The most complex form of carbohydrates C. One form of a very complex fat D. Artificial sweeteners such as saccharin 29. Disaccharides are the joining together of which of the following? A. Three to six monosaccharides B. Two monosaccharides C. A number of monosaccharides D. A fat and a monosaccharide 30. Glycolysis is one of the body’s chemical pathways for which of the following? A. Manufacturing glycogen B. Building proteins C. Producing fats D. Metabolizing glucose 31. Amino acids are the building blocks for which of the following? A. Nucleic acids B. Carbohydrates C. Proteins D. Lipids 32. What is the union of two amino acids using a peptide bond called? A. A dipeptide B. A peptide C. A monopeptide D. A polypeptide 33. Which of the following describes lipids? A. They are a major source of fuel for the body immediately after a meal. B. They are stored for a source of fuel after carbohydrate depletion. C. They are comprised of glycerol and three fatty acids. D. They are metabolized by a pathway called glycolysis. 34. Which of the following describes DNA? A. It is made of two strands of a ribose sugar-phosphate chain. B. It consists of two strands of a deoxyribose sugar-phosphate chain. C. It consists of one strand of a ribose sugar-phosphate chain. D. It is located solely in the mitochondria of individual cells. 35. Use of the periodic table allows prediction of which of the following? A. The properties of each of the elements B. The charge of polyatomic ions C. The number of isotopes in each element D. The potential for discovery of new elements 36. How could water be boiled at room temperature? A. By lowering the pressure B. By increasing the pressure C. By decreasing the volume D. By raising the boiling point 37. What is a combustion reaction? A. It is endothermic. B. It substitutes one element for another. C. It always shares electrons. D. It is a reaction that involves oxygen. 38. What is KCl → K + Cl2 an example of? A. Synthesis B. Decomposition C. Single replacement D. Double replacement 39. Iodine and carbon dioxide undergo sublimation at room temperature and atmospheric pressure. What is this process? A. Changing from a gas to a solid B. Changing from a liquid to a gas C. Changing from a solid to a liquid D. Changing from a solid to a gas 40. An experiment is performed to measure the temperature of boiling water at sea level. The actual boiling point is 104.6° C, 104.5° C, and 104.4° C. What term best describes these data? A. Accurate B. Precise C. Variable D. Equivalent [Show Less]
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HESI CHEMISTRY V1/V2 (140 Questions and Answers)
HESI CHEMISTRY V1/V2 (140 Questions and Answers) 1. If Hydrogen is in a compound, what would its oxidation number be? +1 2. What is the oxidat... [Show More] ion number of any simple ion? The same as the charge of the ion 3. How many kilograms are in a pound? 0.453592 kg 4. What is the temperature for freezing point of water in Celsius? 0 degrees Celsius (32°F for Fahrenheit) 5. What is the conversion of Celsius to Fahrenheit? 5F=9C+160 (remember 5F because you have 5 fingers on a hand & 9C because cats have 9 lives) 6. What is the oxidation number of an element atom? 0 7. What is the freezing point of sea water in Fahrenheit? Below 0C (pick and answer choice around -2C, actual temp depends on how much salt is in the water) 8. How many amino acids are in a dipeptide? 2 9. If Oxygen is in a compound, what would its oxidation number be? -2 10. Which of the following pH values would lemon juice likely have? 2 because the lower the pH value, the more acidic 11. What is a pentose? A 5 carbon sugar (Pent = 5) (ose = sugar) 12. What is the oxidation state of the Sulfur atom in Sulfuric Acid H2SO4? 6 (each H is +1, each O is -2. All charges have to add to 0. 2+S-8=0, so S=6) 13. How many neutrons does carbon 14 have? 8 ( mass# - atomics # = neutrons) 14 - 6 = 8 14. How many protons does Potassium have? 19 (same as the atomic number) 15. How many amino acids are essential for human life? 20 amino acids 16. Normal body temperature in °C? 37°C 17. Normal body temperature in °F? 98.6°F 18. Boiling point of water in °C? 100°C 19. Boiling point of water in °F? 212°F 20. 0°K is equal to °C? -273°C 21. The term Amphoteric means? A substance that can act as both a base & acid 22. What is Kelvin based around? Absolute zero 23. A compound that is a Hydrogen or proton donor, corrosive to metals, causes blue litmus paper to become red and becomes less acidic when mixed with a base is? Acid 24. Mixture of 2 or more metals are? Alloys 25. Acids: • pH less than 7.0 • sour/tart • Formulas begin with H (Hydrogen) • Proton Donor 26. 3 types of radiation in nuclear chemistry? Alpha, Beta & Gamma 27. Alpha radiation: • * Emission of Helium (He) ions in the nuclei • * Contains 2 protons & 2 neutrons. • * +2 Charge • * Largest radiation particle. • * Can be stopped by piece of paper 28. Type of Alloy in which another metal is dissolved in Mercury (Hg)? Amalgam 29. Proteins are made up of? Amino Acids 30. Glycogen is what kind of starch? Animal Starch 31. When an atom GAINS ONE or more electrons? Anions (negative ion) 32. Basic building block of a molecule? Atom 33. Atomic mass? Average mass of an elements isotope 34. Atomic #: # of protons in nucleus of an atom 35. Base? • A Hydrogen or proton ACCEPTOR & has hydroxide group in the makeup of the molecule • Produce -OH • Bitter, slippery, conduct electricity, formulas contain -OH • pH value greater than 7.0 • Proton acceptor 36. Key note: Acids are Proton donors and Bases are proton acceptors 37. Beta radiation: • Decomposition product of a proton or neutron • High speed/energy Electrons • EITHER - charged electrons or + charged positrons • Can be stopped by aluminum foil 38. What is Biochemistry? Study of substances & processes occurring in living things 39. Fahrenheit is based off of? Body temperature 40. How does ↑ Surface area speed up chemical reactions? By ↑ areas of contact where chemical reactions can occur 41. How do catalyst accelerate a chemical reaction? By reducing the amount of energy needed for a reaction to occur A catalyst is a substance that accelerates a reaction by which of the following? -Finding an alternative pathway for a reaction that requires less energy. 42. What does COOH symbolize? A Carboxyl group 43. Which of the following is not a solution type? Catalyst 44. Define Catalyst. Substance that speeds up a chemical reaction. 45. What is an atom called when it LOSES 1 or more electrons? Cations (positive ions) 46. What is chemical bonding? The joining of atoms to form new substances. 2 types: ionic & covalent bonding 47. What is an Ionic bond? • Electrical attraction between 2 oppositely charged atoms called ions • (between metals & nonmetals) 48. Ionic bonding? Chemical bond that’s formed when an atom transfers an electron to another atom. (steals) 49. Single Covalent bond? • • • Chemical bond that shares 1 electron pair Formed by non-metals Sharing is caring! Caring is covalent! 50. What are chemical reactions? Making & breaking of chemical bonds, leading to changes in composition of matter 51. Double Covalent bond? When 2 electron pairs are shared 52. Triple Covalent bond? When 3 electron pairs are shared 53. The following is an example of? Combustion reaction (in combustion, O2 is always a reactant, CO2 and H2O are always products the second reactant is the compound being combusted) 2C2H6 (g) + 7O2 (g) 4CO2(g) + 6H2O 54. What is a combustion reaction? A chemical reaction that occurs when a substance reacts with Oxygen, releasing energy in the form of heat & light (also releases carbon dioxide & water) 55. What is a compound? • Combination of 2 or more elements or atoms. • Made up of atoms of 2 or more different elements joined by chemical bonds 56. Different types of solutions? Compounds, Alloys, Amalgams, Emulsions 57. Strongest type of chemical bond? Covalent 58. What is a decomposition reaction? A SINGLE compound breaks down to form 2 or more simpler substances 59. What is Deoxyribose? A sugar used in the formation of DNA 60. Attractions between opposite charges of polar moles? Dipole-dipole forces 61. What is a Disaccharide? A double sugar molecule made of 2 monosaccharides bonded together through dehydration synthesis. 62. When 2 monosaccharides are joined together this makes? Disaccharide 63. Type of chemical bond that share 2 electron pairs? Double covalent bond 64. Example of double replacement? AB + CD = AD + CB (swapping dance partners) 65. Example of Single replacement? A + BC B + AC (one dancer cutting in on two partners) 66. Group of electrons revolving around the nucleus of an atom, or known as a cloudlike group of electrons? Electron clouds 67. Mixtures of matter that readily separate such as water and oil? Emulsion 68. 3 common temperature systems? Fahrenheit, Celsius, Kelvin 69. Celsius is based around? Freezing & boiling point of water 70. What is oxidation? Loss of electrons (OIL: oxidation is losing) 71. What is reduction? GAIN of electrons (RIG: reduction is gaining) 72. Gamma radiation: • Similar to xrays • Can be stopped by several feet of concrete or several inches of Lead • High energy electromagnetic radiation lacking charge and mass 73. Unit measure of weight? Gram 74. Basic units of METRIC system? Gram, Liter, Meter 75. What are Hydrogen bonds? Weak attraction between a hydrogen atom in one molecule & another atom in a different molecule. 76. Examples of intermolecular forces? Hydrogen bonds, dipole-dipole, dispersion forces (attractions between two different molecules. Intramolecular bonds are ionic & covalent bonds within a single molecule) 77. 4 basic ways to speed up a reaction? ↑ temperature, ↑ Surface area, ↑ catalyst & ↑concentration 78. What are intermolecular forces? Forces of attractions between molecules 79. Where are nucleic acids, DNA & RNA found? Cell nucleus 80. Atoms of the same element but have different numbers of neutrons? Isotope 81. Gluconeogenesis is a process that produces? Glucose from proteins and fats rather than carbohydrates 82. A way to express concentration of atoms? Molarity 83. Part of the nucleus of an atom that has no charge? Neutron 84. What is the Molarity Formula? Moles of Solute =Molarity Liters of Solution 85. Single sugar molecules? Monosaccharides 86. How does ↑ concentration cause reaction acceleration? More potential for contact (chemical reaction) 87. Which is an example of a ionic bond? NaCl (Sodium Chloride) because it contains a metal and a non-metal (metal is always first) 88. In a covalent bond compound, if the electrons are shared equally, then the bond is? Non-polar (water hating, equal) 89. The study of changes that occur in atomic nuclei? Nuclear Chemistry 90. Polar Covalent bond? Unequal sharing of electrons (water loving) 91. When 3-6 monosaccharides join together this is called? Oligosaccharide (7 or more: polysaccharide. Sometimes 3 or more is called a polysaccharide) 92. Emission of particles or energy from an unstable nucleus? Radioactivity 93. Particles that are emitted during radioactivity? Radiation 94. Reactant is? A chemical substance that is present at the start of a chemical reaction. Reactant Product 95. A substance that is dissolved in a solution? Solute (the liquid it is dissolved in is the solvent. In salt water, salt is the solute & water is the solvent) 96. A homogenous mixture of 2 or more substances? Solution 97. Liquid substance capable of dissolving other substances? Solvent 98. Define stoichiometry. Calculation of quantities in chemical reactions 99. Combining parts into a whole is? Or synthesis is? • • Synthesis Chemical reaction in which 2 elements or simpler compounds combine to form a product 100. How many electrons does an Oxygen ion have? 10 (Atomic # of 8 & is in group VIA which has a -2 charge, which means it has 2 more electrons than the 8 protons) 101. What is the charge of Potassium (K) in KCl? +1 because K is found in group IA 102. What is the mass of 1 mole of CO2? 44g/mol (C =12.011 + (15.999 x 2) = answer. You will be given the masses of the individual elements) 103. How many moles of atoms are present in 2 moles of O2? 4 (2 atoms in each molecule x 2 moles = 4 moles) 104. What characterizes a chemical reaction as combustion? The chemical reaction that is the reaction of a compound with Oxygen? • O2 is a reactant, CO2 and H2O are products • Combustion 105. Sum of oxidation # =? Charge on polyatomic ion 106. Increasing the causes the particles to have greater kinetic energy, allowing them to move faster and have a greater chance of reacting. Temperature 107. To balance an equation, what is placed in front of each component? Coefficient 108. Dispersions forces are found in which covalent bond? All (polar and non-polar) 109. The weakest of all intermolecular forces? Dispersion forces 110. A Dipole attraction is a intermolecular force? Weak 111. What is created when an electron pair in a covalent bond is shared unequally? Dipole 112. The attractions of one dipole to another is? Dipole interactions 113. Strongest bond of intermolecular forces? Hydrogen bond (but weaker than ionic and covalent, which are intramolecular bonds) 114. Elements Flourine (F), Chlorine (Cl ), Oxygen (O) and Nitrogen (N) are involved in which bond? Hydrogen bond 115. Polarity is? Based on the difference in electronegativity values for the elements involved 116. What reactions take place in the nucleus to obtain stable nuclear configurations? Nuclear reactions 117. Mass # - Atomic # = # Neutrons in an element 118. Protons + Neutrons = Mass # 119. # of Protons in an element = Atomic # 120. Neutral subatomic particles = Neutrons 121. – charge subatomic particles = electrons 122. + charge subatomic particles = Protons 123. Charge of noble gases? 0 124. Group IA = +1 Charge 125. Group IIA = +2 Charge 126. Group IIIA = +3 Charge 127. Group VA = -3 Charge 128. Group VIA = -2 Charge 129. Group VIIA = -1 Charge 130. Rows on periodic table: Period (Horizontal Left/right) (remember: “R” and “P” look very similar) 131. Columns of periodic table: Group (Vertical up/down) (remember: “C” and “G” look very similar) 132. How elements are arranged on the periodic table? By their chemical properties 133. Matter that has definite shape & volume? Solid 134. Matter that changes in volume with changes in temperature & pressure? Gas 135. Which change of matter is when no change is made to the chemical composition of a substance? Physical (if the chemical composition changes, it’s a chemical change. Boiling water is physical because it’s H2O before and after. Changing H2O to H2 and O2 is a chemical change) 136. Simplest substance and is represented by a letter or letters? Element 137. Law that states matter can neither be created nor destroyed during a chemical reaction (but it can change forms)? Law of conservation of mass 138. Law that states energy can neither be created nor destroyed (but it can change forms)? Law of conservation of energy 1-H 2-HE 3- LI 4- BE 5 B 6- C N 7 0 8 F9 NE 10 11- NA 12- Mg 13- AL 14-SI 15-P 16-S 17-Cl 18-Ar K- 19 CA- 20 [Show Less]
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HESI A2 Chemistry
Question Answer Matter that has a definite shape and volume solid Matter that changes in volume with changes in temperature and pressure gas A cha... [Show More] nge of matter is when no change is made to the chemical composition of a substance. physical Simplest of substances and is represented by a letter or letters element Law that states matter can neither be created nor destroyed during a chemical reaction Law of conservation of mass The breaking of bonds and reforming of new bonds to create new chemical compounds with different chemical formulas and different chemical properties Chemical reaction 5 main chemical reactions synthesis, decomposition, combustion, single replacement, double replacement Chemical reaction in which 2 elements combine to form a product synthesis Chemical reaction that is the breaking of a compound into component parts decomposition The chemical reaction that is the reaction of a compound with oxygen combustion Chemical reaction that consists of an active metal reaction with an ionic compound creating a new compound single replacement Chemical reaction involving 2 ionic compounds; the reactant yields "switched partners" double replacement how elements are arranged on the periodic table by their chemical properties Number that represents the # of protons an atomic number element has average of the masses of each of its isotopes as they occur in nature atomic mass Mass number - atomic number = # of neutrons in an element Columns of the periodic table = groups Rows of the periodic table = periods Group IA = charge +1 Group IIA = charge +2 Group IIIA = charge +3 Group VA = charge -3 Group VIA = charge -2 Group VIIA = charge -1 Charge of noble gases 0 Positively charged ions protons Negatively charged ions electrons Neutral ions neutrons # of proteins in an element = atomic number proteins + neutrons = mass number In reactions, atoms try to reach stable electron configurations. chemical reactions take place in the nucleus, to obtain stable nuclear configurations. nuclear Word used to describe the emission of particles from an unstable nucleus. radioactivity The particles that are emitted during radioactivity radiation 3 types of radiation alpha, beta, gamma Radiation that is the emission of helium ions alpha Alpha radiation particles have a charge of +2 How can penetration from alpha particles be stopped? piece of paper Radiation that is a product of the decomposition of a neutron. It is composed of high-speed, high- energy electrons. beta radiation How can beta radiation particles be stopped? aluminum foil radiation is high-energy electromagnetic radiation that lacks charge and mass. gamma What radiation can be stopped by several feet of concrete or several inches of lead? gamma radiation 2 types of chemical bonding ionic & covalent What bond is an electrostatic attraction between 2 oppositely charged ions? (between metals & nonmetals) ionic A single bond is formed when 2 atoms share a pair of electrons. covalent A bond is formed when 2 electron pairs are shared. double covalent A bond is formed when 3 electron pairs are shared. triple covalent What is the strongest type of chemical bond? What is it formed by? covalent bond; non-metals In a covalent bond compound, if the electrons are shared equally, then the bond is . non-polar If electrons are not shared equally in a covalent bond, the bond is . polar is based on the difference in electronegativity values for the elements involved polarity Hydrogen bonding, dipole interactions and dispersion forces. intermolecular forces Bond that is the attraction for a hydrogen atom by a highly electronegative element. hydrogen bond Elements fluorine, chlorine, oxygen and nitrogen are generally involved in a bond. hydrogen Bond that is the strongest of the intermolecular forces hydrogen The attractions of one dipole for another dipole interactions A is created when an electron pair in a covalent bond is shared unequally dipole A dipole attraction is a intermolecular force. weak The weakest of all intermolecular forces. dispersion forces Dispersion forces are typically found in covalent compounds. Non-polar 6.02 x 10^23 is a mole The mass of one mole of a substance atomic mass The part of chemistry that deals with the quantities and numeric relationships between compounds in a chemical reaction. stoichiometry To balance an equation, are placed in front of each component. coefficient 4 ways to increase the reaction rate increase temperature, increase surface area, increase concentrations and reactants and add a catalyst Increasing the causes the particles to have greater kinetic energy, allowing them to move faster and have a greater chance temperature Accelerates a reaction by reducing the activation energy, or the amount of energy needed for a reaction to occur. catalyst reaction involve the transfer of electrons from one element to another redox The loss of electrons oxidation The gain of electrons reduction Sum of oxidation #'s = The charge on polyatomic ions Compounds acting as hydrogen-ion donors acids Compounds acting a hydrogen-ion acceptor bases pH value less that 7.0; taste sour/tart; produce h30+ (most of their formulas begin with H) acids Produce OH-; taste is bitter, feels slippery; conduct electricity; formulas contain OH-, pH value is greater than 7.0 bases What characterizes a chemical reaction as combustion? adding O2 What is the change of potassium in KCl? +1 because K is found in group IA How many electrons does an oxygen ion have 10 (it has an atomic # of 8 and is in group VIA, which has a -2 charge, which means it has 2 more electrons than he 8 protons). How many neutrons does an atom of carbon -14 contain? 8 (take the mass #-atomic # = neutrons) 14-6=8 What is the strongest type of chemical bond? covalent bond What is the mass of one mole of CO2? 44g/mol (C=12.011 + (15.999 x 2) = answer) How many moles are present in 2 moles of O2? 1.204 x 10^24 (1 mole - 6.02 x 10^23, 2 mole would be double that) What would be the oxidation state of the sulfur atom in sulfuric acid, H2SO4? +6 [Show Less]
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