chem midterm study guide

number of naturally occurring elements

90

number of lab-created elements

28

most abundant element in earth’s crust

oxygen

AMU is a unit of measurement equal to

the mass of one proton

metals are

good conductors, shiny, malleable, ductile, corrosive

metalloids are

shiny or dull, semi-good conductors, ductile, malleable

the metalloids include

B, Si, Ge, As, Sb, Te, [Po, At]

nonmetals are

poor conductors, not ductile/malleable, brittle, dull, gases

families/groups are

columns of elements w similar but not identical properties w same number of valence electrons

periods are

rows of elements w different properties (first is extremely active solid; last is inactive gas)

hydrogen

has no family, sits above alkali family

alkali metals

are the first column, all have 1 valence electron, shiny, clay consistency, easily cut w knife, most reactive (violent w water), always naturally bonded w another element

reactive elements

bond easily w other elements to form compounds, are reactive if they do not have a complete valence electron level (rule of octet)

alkaline earth metals

are group 2, always combined w other elements in nature (typically salt)

transition metals

groups 3-12, all elements in B families, good conductors, brightly colored, 1-2 valence electrons (more often 2), in d block (up to 10 electrons) so cannot lose enough to attain noble gas configuration, combine w oxygen to form oxides, properties do not fit w any other families

boron/earth metals

group 13, boron is metalloid, all others are metals, includes aluminum (most abundant metal in earth’s crust)

carbon/tetrel

group 14, carbon is nonmetal, all others metals/metalloids, carbon is “basis of life”—organic chemistry

nitrogen/pnictogen

group 15, nitrogen makes up 78% of earth’s atmosphere, contains metals/metalloids/nonmetals, tend to share valence electrons when bonding

oxygen/chalcogen

group 16, mostly shares electrons when bonding, oxygen is extremely active and combines w nearly all elements

halogen

group 17, fluorine, chlorine, bromine, astatine, iodine, most active nonmetals, never found free in nature, form salts w alkali metals

noble gases

group 18, colorless, unreactive gases, inactive bc outermost energy level is full, called inert, all found in small amounts in atmosphere

rare earth elements/inner transition metals

30, lanthanides & actinides, one in lanthanides and most in actinides are trans-uranium (synthetic)

liquid metals:

bromine & mercury

gases are all

nonmetals

all actinides are

radioactive

molecules of one substance are called

pure

representative elements are

groups 1, 2, 13-18

si base unit for mass

kilogram

precision

how close multiple measurements are to each other

accuracy

how close a measurement is to the accepted/correct value

percent error

|experimental value - accepted value|/accepted value*100

Law of Definite Proportion

a given compound has a fixed ratio of elements

Law of Conservation of Mass

matter is neither created nor destroyed (Lavoisier)

deposition

gas to solid

sublimation

solid to gas

Periodic Law

elements organized by atomic number fall into recurring groups and are a function of their atomic number

second most abundant gas in the atmosphere

oxygen

all are diatomic

halogens

members include all states of matter

halogens

cations are

smaller than neutral atoms

anions are

larger than neutral atoms

electronegativity

indicates the ability of an atom to attract electrons when chemically bonded

photoelectric effect

emission of electrons from a metallic surface when light of a certain frequency shines on it

quantum

a particle of electromagnetic radiation with no mass that carries a quantum of energy

aufbau principle

electrons fill lower energy orbitals before higher energy levels

pauli exclusion principle

two electrons in an orbital must have opposite spins

hund’s rule

electrons in a subshell must occupy different orbitals before being paired

diamagnetic

all electrons are paired and atom slightly repels magnets

paramagnetic

not all electrons are paired and atom slightly attracts magnets

extensive properties

vary with the amount of substance (mass, volume, weight)

intensive properties

do not vary with amount of substance

taste and odor are

chemical properties

air, bronze, milk, gas, ink, and concrete are

mixtures

distillation

boiling, going through a sill, and condensation

chromatography

separation and purification of a mixture

Heisenberg Uncertainty Principle

if you know position of a particle, you can’t know its velocity and vice versa

Democritus

all things are composed of minute, invisible, indestructible particles of matter which move about eternally in infinite empty

Aristotle

against atomic theory, believed the four elements were water, fire, earth, and air

John Dalton

chemical properties unique to elements, atoms cannot be destroyed/broken down (false!), atoms of dif elements combine in whole number ratios, solid sphere model, father of modern atomic theory

J. J. Thomson

discovered electrons, plum pudding model, showed that cathode rays were made of electrons

Ernest Rutherford

alpha particles (stripped hydrogen atoms) through gold sheet showed positively charged nucleus, discovered protons, nuclear model

Niels Bohr

Danish, measured line spectrum of hydrogen, proposed electron shells (dif. energy levels) in planetary model

Erwin Schrodinger

Austrian physicist who explained electron’s movement w/ wave equation, no set orbits, created quantum model

James Chadwick

student of Rutherford who discovered neutrons, bombarded beryllium nuclei w/ alpha particles to discover new radiation

Antoine Lavoisier

“father of modern chemistry,” list of 33 elements (“simple substances”),

Mendeleev

left gaps for “eka-” elements in periodic table organized by atomic mass, predicted “eka-aluminum” (gallium)

Henry Moseley

ordered elements by atomic number, indicating how many natural elements were to be discovered

Robert Millikan

American physicist who determined the magnitude of an electron’s charge (oil-drop experiment), photoelectric effect

Billiard ball model

Dalton

Plum Pudding Model

JJ Thomson

Nuclear Model

Rutherford

Planetary Model

Bohr

Quantum Mechanical Model

Schrodinger

Electron Cloud Model

Schrodinger

cathode ray tube

used by JJ Thomson to discover electrons,

gold foil experiment

alpha particles through gold foil showed atoms are mostly empty space and had nuclei

oil drop experiment

Milikan discovered the exact charge of an electron of drops in an oil mist