A = mass number of the atome

Z = atomic number

X = the atom

electrons close to the nucleus = ower electric potential energy

eleectrons closer to outer regions or shells = higher electric potential energy

electrons in the outtermost energy level or shell

experience the least electrostatic draw to their nucleus = more likely to become involved in bonds with other atomes

mass in grams of one mole of atoms

a mole = 6.02 x 10²³

protium: one proton and atomic mass of 1 amu

deuterium: 1 proton and 1 neutron; atomic mass of 2 amu

tritium: 1 proton and 2 neutrons; atomic mass of 3 amu

quanta

E = hƒ

where h = Planck's constant = 6.626 x 10^-34 Jxs

and ƒ = frequency of radiation

L = nh/2π

where h = 6.626 x 10^-34 J x s

and n = quantum number (which can be any positive integer)

note: because n is the only variable integer in the formula, the angular momentum of an electron changes only in discrete amounts with respect to the quantum number

E = -R_H / n²

where R_H = Rydberge constant = 2.18 x 10^-18 J/electron

note: according to this equation, the energy of the electron changes in discrete amounts with respect to the quantum number as well

note: the electron in any of its quantized states in the atom will have a negative energy as a result of the attractive forces between the electron and the proton

note: the energy of an electron increases the further out from the nucleus that it is located

E = hc/λ

where h = planck's constant = 6.626 x 10^-34

and c = speed of light = 3 x 10⁸

and λ = the wavelength of the radiation

hydrogen emission lines of transitions from levels n > 2 to energy level n = 2

inclues 4 wavelengths of visible light

hydrogen emission lines corresponsding to transitions from the n > 1 to n =1 energy levels

inclues larger energy transitions = shorter photon wavelengths in the UV region of the EM spectrum

E = hc/λ = -R_H[1/n_i² - 1/n_f²]

the energy of the emitted photon corresponds to the precise difference in energy between the higher energy initial state and the lower energy final state

it is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron

if we want to assess the position of an electron: the electron must stop = changing its momentum

if we want to assess the momentum of the electron: the electron has to be moving = changing its position

can take on any positive integer value

the larger the integer value = the higher the energy level and radius of the electron's orbit(al)

within each shell of some n value, maxim number of electrons = 2n²

the difference in energy between 2 shells decreases as distance from the nucleus increases

refers to the shape and number of subshells within a give nprincipal energy level (shell)

has important implicatiosn for chemical bonding and bond angles

the value of n limit the value of l: range of possible l value is 0 to (n-1)

l = 0; s-subshell

l = 1; p-subshell

l = 2; d subshell

l = 3; f-subshell

max. number of electrons in a subshell: 4l + 2

specifices the particular orbital within a subshell where an electron is highly likely to be found at a given moment in time

each orbital can hold a max. number of electron of 2

possible values of m_l = -l to +l including 0

electron has two spin orientations designated by +1/2 and -1/2

2 electrons in the same orbital must have opposite spins

electrons in different orbitals with the same spinal = parallel spins