GenChem1 Ch 1-3

solid

has fixed shape and volume

liquid

takes shape of container; forms horizontal surface; has fixed volume

gas

expands to fill container

evaporation

liquid to gas

condensation

gas to liquid

sublimation

solid to gas

deposition

gas to solid

freezing

liquid to solid

melting

solid to liquid

pure substance

element or compound

mixture

homogenous or heterogenous

extensive

changes based on amount (mass, volume, energy required to boil)

intensive

does not change based on amount (density, boiling point, ratios)

accuracy

closeness of a measurement to accepted value

precision

consistency of a measurement, meaning the results are close to each other

monatomic

exist as stable, independent atoms (noble gases)

diatomic

naturally exist as a molecule of 2 atoms bonded (N,O,H,Cl)

atoms

smallest unit of an element, made of protons, neutrons, electrons

elements

atoms with a specific number of protons

compounds

atoms of two or more elements in a whole-number ratio

molecule

atoms of two or more of the same element bonded together

chemical bond

strong attraction between atoms

covalent bonds

between nonmetal atoms (makes molecules)

ionic bonds

between metal and nonmetal atoms (makes crystals)

chemical reaction

bonds are broken and/or formed between atoms; number of atoms of each element is preserved

protons

in nucleus, charge is 1+, =1amu

neutron

in nucleus, charge is 0, =1amu

electron

in orbitals, charge is 1-, =0amu

atomic number

number of protons

mass number

protons plus neutrons

charge

protons (+) + electrons (-)

anion

negatively charged atom: gained electron

cation

positively charged atom: lost electron

isotopes

same number of protons but different number of neutrons

natural abundance

percent of an element that is one isotope

atomic mass

weighted average of natural isotopes

simple average

add then divide

weighted average

multiply then add

4 ways to represent a molecule

formula, lewis structure, ball and stick, space filling

empirical formula

lowest whole-number ratio of elements **always used for ionic compounds

light behaves as

both a wave and a particle

wavelength

distance between peaks