Chemistry Unit 5 Test Study Guuide

electromagnetic radiation

a form of energy that exhibits wave-like behavior as it travels through space

amplitude

how much energy a wave carries; the vertical distance from the origin to the crest

wavelength

the distance between a point on a wave and the nearest point just like it

frequency

the number of wavelengths that pass a fixed point each second; measured in Hz or s-1; as frequency increases, energy increases and wavelength decreases

crests

the highest points of a wave

troughs

the lowest points of a wave

hertz (Hz)

a unit of frequency equal to one cycle per second

continuous spectra

spectra that contain all colors (R O Y G B I V)

line spectra

sharp lines in the spectrum of light emitted or absorbed by an element

Planck’s constant (h)

6.626 x 10^-34 J x s

speed of light (in a vacuum)

the speed for which all eleecrtomagnetic waves travel; 3.00 × 10⁸ m/s

qunatum

the minimum amount of energy that can be gained or lost by an atom; matter gains or loses energy only in small, specific amounts

ground state

he lowest energy level of an atom

excited state

the state of an atom after it absorbs energy and has electrons in higher energy levels

Heisenberg uncertainty principle

it is fundamentally impossible to know both the velocity and position of a particle at the same time

de Broglie equation

predicts that all moving particles have wave characteristics; λ = h/mv (wavelength=Planck’s constant/(mass of the particle x velocity)

principal energy level

a region of space in whcih electrons can move about the nucleus

atomic orbital

a region of space with a high probability of finding an electron; each orbital contains a maximum of 2 electrons of opposite spins

sublevels

are contained within the principal energy levels

quantum numbers

numbers that specify the address of each electron in an atom; describe the properties of electrons in orbitals

n, principal quantum number

electron’s energy depends principally on this; tells which principal energy level an electron is in (ie n=1, n=2, . . . )

l, anglar quantum number

determines the shape of an orbital (ie s-spherical, p-dumbell, d-2 dumbell, f-flower)

m₁ , magnetic quantum number

indicats the orientation of an orbital around the nucleus on the x, y, and z axises

m_s , spin quantum number

identifies the 2 possible spin orientations of an electron in an orbital; has 2 possible values (clockwise 1/2 and counter-clockwise -1/2)

Aufbau principle

states that an electron occupies the lowest energy orbital in order of increasing energy

Pauli exclusion principle

a maximum of 2 electrons can occupy a single orbital if they have opposite spins; 2 electrons in orbitals must have opposite spins

Hund’s rule

orbitals of equal energy are each occupied by 1 electron before any is occupied by a second in a sublevel

quantum theory

describes mathematically the wave properties of electrons and very small particles.