chemistry final_ chapters 1-3

element

composed of one type of atom

compound

composed of two or more elements

homogenous mixture

a mixture with a uniform composition throughout

heterogenous mixture

a mixture with a non-uniform composition

physical properties

characteristics that can be observed or measured without changing the substance's identity. (phase changes, mixing, size changes, dissolving)

chemical properties

characteristics that are observed only after a chemical reaction has taken place (rusting, combustion, spoiling)

extensive properties

depend on amount of material used

intenstive properties

does not depend on the amount but the nature of element

density

mass/volume

law of mass conservation

matter can neither be destroyed or created, only changed in form

law of multiple proportions

when an element combines with a different element to form multiple compounds, the ratio of the masses of one element to a fixed amount of the second element is the ratio of small whole number

law of definite composition

 a given compound always has the same composition, regardless of where it comes from

what did Dalton do

elements are made of tiny particles

atoms are indestructible

compounds always have the same relative numbers and types of atoms

all atoms of a given element are identical

what did thompson do

cathode rays tubes, discovered electron, plum pudding model

Millikan's oil drop experiment

 found the charge of an electron

rutherford

discovered nucleus using gold foil experiment

atomic number

number of protons in an atom of an element

mass number

mass of atom (protons+neutrons)

average atomic mass

atomic mass= sum of (mass of isotope) (fractional abundance of isotope)

wavelength

distance between troughs

frequency

number of waves that pass a particular point in 1 second

speed of light

height of wave

photoelectric effect

a phenomenon in which electrons are emitted from the surface of metal when light strikes it

absorption

excitement

emisson

relaxation

energy of a photon

E=hv=hc/λ

energies and wavelengths of emitted photons

-2.179× 10^-18 (1/nf - 1/ni)

de brogiles wavelength

λ=h/vm

Heisenberg uncertainty principle

it is impossible to know simultaneously both momentum and position of a particle with certainty

schrodinger’s equation

explains the wave-particle duality of the electron

principle quantum number (n)

corresponds to Bohrs energy level, shells or levels

angular momentum quantum number (l)

describes the shape of the orbital, referred to as subshells, equal to (n-1)

magnetic quantum number (ml)

orientation of space in orbital, possible values of -l to l

electron spin (ms)

½ or -1/2

pauli exclusion principle

if an orbital can only hold 2 electrons, then the maximum number of electrons allowed in any sublevel can be determined

hunds rule

the most stable arrangement of electron in a subshell is the one with the greatest number of unpaired e-s or parallel spins

aufbau principle

energy level and sublevels fill from lowest energy to high s p d f

Outer electrons or valence electrons

highest energy level (highest n level)

core electrons

non-valence electrons

diamagnetic

not attracted to a magnetic field

paramagnetic

attracted to a magnetic field

atomic radius

increases down a group, decreases across period (Rb is the biggest atom)

ionization energy

the minimum amount of energy required to remove an electron from an atom or ion—> decreases down a period, increases as you move across a period (helium has the highest ionization energy)

exceptions to ionization energy pattern

boron and beryllium because it costs less energy to ionize

electron affinity

how likely an atom is to accept an electron- increases across a period

metallic character

metallic character increases down a group, decreases across a period (Fr is the most metallic)

periodic trends