CHEM 120 Midterm Study Guide
Designing an Experiment
• What makes a good hypothesis?
• Design experiments by changing only a single variable –
... [Show More] why is this important?
• What are the differences between an independent, dependent and controlled variable?
Units and density
• Know metric units for mass, length, volume, time and temperature.
• Recognize prefixes and know what they mean (kilo-, centi-, milli- etc.)
• Know the units for density and be able to calculate.
• The density of water is 1 g/mL – what is the mass of 0.500 L of water?
• Be familiar with the mole and avogadro’s number (6.02x1023)
Isotopes
• What is an isotope? How many protons, neutrons and electrons are in:
o 56Fe, 238U, 3H, 218Pb
• Explain the difference between mass number and atomic mass
• How does the atomic mass of an element inform you about the relative abundance of different isotopes for a given element?
Identifying ionic and covalent molecules
• Cations are easier to identify than anions - use this to help identify ionic vs. covalent
• Polar vs. nonpolar covalent bonds, factors that determine and physical implications
• Naming conventions for ionic vs. covalent
• Polyatomic ions. Make sure to remember charge along with formula and name.
• Balancing charge on ionic compounds to write its formula given only its name
Electron configuration
• Using the periodic table, be able to write the ground state electron configuration for an element
• Explain how these configurations show the most common charge for an ion
Lewis structures
• Draw Lewis structures (electron dot structures) for elements and molecules
• Use Lewis diagrams to identify molecular geometry and polarity
• Explain the following terms: polar bond, electronegativity, polar molecule
Converting moles and grams
• Calculate molar mass using the periodic table
• Use molar mass to convert moles to grams, or vice versa
Stoichiometry
• Balance chemical reactions
• Use balanced chemical equation to compare moles of compounds in reactions
• Solve for amount of product expected given a chemical equation and mass of reactant
Concentration (Molarity, m/v%)
• Define molarity and m/v% and calculate
• Calculate quantity of water needed to dilute solutions and vice versa (C1V1 = C2V2)
Intermolecular forces (IMFs)
• List types of IMFs in terms of increasing strength
• Relate strength of intermolecular forces to physical properties
• Define the term hydrogen bonding and describe significance
Boyle, Charles, Avogadro and contributions to the Ideal Gas Law
• Calculate changes to Pressure when volume changes (and vice versa – Boyle)
• Calculate changes to Temperature when volume changes (and vice versa – Charles)
• Understand how these two laws make the combined gas law
Ideal gas law
• Understand the kinetic molecular theory of gasses and how making certain approximations describes an ideal gas
• Relate Avogadro’s law to an ideal gas
• Know how gas properties change in response to other changes (Boyle, Charles, etc.)
• Calculate Temperature, Volume, Pressure or moles given 3 other properties
Acids/bases Buffers
• Define acids and bases based on the Bronsted-Lowry definition
• Recognizing which compound acts as an acid vs. a base in reactions
• Define weak acid vs. strong acid
• Define a buffer solution, and understand how it responds to addition of acid or base
Redox reactions
• Recognize a reaction as a redox reaction
• Identify oxidizing vs. reducing agent
• Oxidation number and its usefulness in identifying electron flow [Show Less]