HESI-A2 CHEMISTRY
Chemistry note cards for HESI entrance exam
Question Answer
Matter that has a definite shape and volume solid
Matter that changes in
... [Show More] volume with changes in temperature and pres- sure
gas
A change of matter is when no change is made to the chemical composition of a sub- stance.
physical
Simplest of substances and is rep- resented 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 reform- ing 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 replace- ment, double replacement
Chemical reaction in which 2 ele- ments combine to form a product synthesis
Chemical reaction that is the break- ing of a compound into component parts
decomposition
The chemical reaction that is the reaction of a compound with oxy- gen
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 element has atomic number
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 configura- tions.
chemical
reactions take place in the nucleus, to obtain stable nu- clear configurations.
nuclear
Word used to describe the emission of particles from an unstable nu- cleus.
radioactivity
The particles that are emitted dur- ing radioactivity radiation
3 types of radiation alpha, beta, gamma
Radiation that is the emission of he- lium 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-en- ergy 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 gamma radiation
several feet of concrete or several inches of lead?
2 types of chemical bonding ionic & covalent
What bond is an electrostatic at- traction 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 chem- ical 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 interac- tions and dispersion forces. intermolecular forces
Bond that is the attraction for a hy- drogen atom by a highly elec- tronegative element.
hydrogen bond
Elements fluorine, chlorine, oxygen and nitrogen are generally involved in a bond.
hydrogen
Bond that is the strongest of the in- hydrogen
termolecular forces
The attractions of one dipole for an- other dipole interactions
A is created when an elec- tron pair in a covalent bond is shared unequally
dipole
A dipole attraction is a in- termolecular force. weak
The weakest of all intermolecular forces. dispersion forces
Dispersion forces are typically found in covalent com- pounds.
Non-polar
6.02 x 10^23 is a mole
The mass of one mole of a sub- stance atomic mass
The part of chemistry that deals with the quantities and numeric re- lationships 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, in- crease 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 re- catalyst
action to occur.
reaction involve the trans- fer of electrons from one element to another
redox
The loss of electrons oxidation
The gain of electrons reduction [Show Less]