chem 120 final exam review

chemistry is…

the study of composition, structure, properties, and reactions of matter

a chemical is…

a substance that maintains the same composition and properties regardless of where it is found

base unit of mass

kilogram

base unit of length

meter

base unit of volume

liter

base unit of time

seconds

base unit of temperature

kelvin

decimal place holder

does not count as SFs

ex: 0.0048 - two SFs

trailing zero in a nondecimal number

does not count as SFs

ex: 500 - 1 SF

multiplication/divison rule for counting SFs

answer must have the lowest number of SFs

addition/subtraction rule for counting SFs

answer must have the least number of decimals

exact numbers

numbers obtained w/o a tool

matter

anything that occupies space and has mass

pure substance

compounds and elements

homogeneous mixture

salt water - all salt dissolved in mixture

heterogeneous mixture

sand and water mixture - sand does not dissolve

compound

always have a chemical formula

NaCl

law of conservation of mass

law that states that mass is always conserved in chemical reactions

law of conservation of energy

law that states that the energy you start with in a reaction is the energy that you end with

atom

the smallest identifiable part of an element

dalton’s atomic theory

states that atoms are neither created nor destroyed during a chemical reaction

how are isotopes represented?

mass number on top, atomic number on bottom

ionization energy

energy required to remove an outermost electron

alpha radiation

least penetrating type of radiation

^4₂He

beta radiation

^0_-1e

positron radiation

^0₁e

gamma radiation

most penetrating type of radiation

^0₀y

transmutation

process by which a stable nucleus is bombarded by high energy/speed particles and converted to a radioactive isotope

chemical bonds

attraction that involves the electrons of two elements being shared or transferred

happens because atoms want to become stable

ionic bonds

metal + nonmetal

transfer of electrons

covalent bonds

nonmetal + nonmetal

sharing of electrons

dispersion forces

present in all molecules

weak forces

more electrons = greater dispersion forces

dipole - dipole forces

forces present only in polar molecules

hydrogen bonding

bonds formed specifically with hydrogen to fluorine, oxygen, or nitrogen

kinetic molecular theory: gas behavior

1) gas particles are very small and move rapidly

2) no alternative forces between particles

3) very small volume when compared to the volume of the container

4) they are moving constantly in straight lines

5) kinetic energy is directly proportional to temp. in kelvin

boyle’s law

states that pressure and volume are inversely related to each other

P1V1 = P2V2

ex: inhalation and exhalation

charles law

states that volume and kelvin temp. are directly related when there is no change in pressure and amount of gas

v1/t1 = v2/t2

gay-lussac’s law

states that pressure and kelvin temp. are directly related when there is no change in volume and amount of gas

p1/t1 = p2/t2

combined gas law

relationship of pressure, volume, and temp. when amount of gas does not change

p1v1/t1 = p2v2/t2

avagrado’s law

volume is directly related to number of moles when when pressure and temp. don’t change

v1/n1 = v2n2

ideal gas law

PV = nRT

R = idea gas constant (0.0821)

standard temperature

0 degrees celcius, or 273 degrees kelvin

standard pressure

1 atm, or 760 mmHg

dalton’s law of partial pressures

states that total pressure is the sum of the partial pressure of each gas

oxidation-reduction reactions

oxidation - loss of electrons, reduction - gain of electrons (OIL RIG)

ex: substance reacts with O2, metal reacts with nonmetal, one substance transfers electrons to another substance

limiting reactant

reactant that is completely consumed in the reaction and makes the least amount of product

theoretical yield

amount of product based on the amount of limiting reactant

percent yield

actual yield/theoretical yield x 100%