Chapter 1 Atomic Structure Flashcards
protons
- found in the nucleus of an atom
- e= 1.6 x 10^-19 C
- 1 amu
- equal to the atomic number
neutrons
- no charge
- make up nucleus with protons
mass number
sum of protons and neutrons
isotopes
- same atomic number, different masses
electrons
- move through space around nucleus
- negative charge
electron shells
- lower electron shell, closer to nucleus, lower energy levels
- higher electron shell, farther from nucleus, higher energy levels
Valence electrons
- electrons farthest from nucleus
- strong interaction with environment, weak interactions with nucleus
- more likely to become involved in bonds with other atoms
- determine reactivity of the atom
describe sharing of valence electrons
- allows elements to fill their highest energy levels to increase stability
- neutral… = numbers of proton and electrons
- gain electrons, atom gains negative charge
- lose electrons, atom gains positive charge
cation
positively charged atom
anion
negatively charged atom
Avogadro’s number
- 6.02 x 10^23 = one mole
Planck relation
- energy of a quantum
- E = hf
h = plancks constant (6.626 X 10^-34 J*s)
f = frequency of radiation
Angular momentum
- L = mvr
Kinetic energy
K = 1/2 mv^2
Bohr model of angular momentum
- L = (nh)/(2pi)
n = principal quantum number
h = planks constant (6.626 x 10^-34 J*s)
Energy of the electron
- E = - ( R_H) / (n^2)
- R_H is rydberg unit of energy (2.18 X 10^-18 J/electron)
- energy of an electron increases (less negative) the further from the nucleus (increasing n)
ground state
- lowest energy radius n = 1
- all electrons in the lowest possible orbital
excited state
- electrons moved to an orbit with a larger radius
- at least one electron has moved to a subshell of higher than normal energy
- often as a result of heat or other energy forms to cause excited state
Electromagnetic energy emitted from photon when returning to ground state
- E = hc / gamma
h = plancks constant (6.626 x 10^-34)
c = speed of light (3.00 X 10^8 m/s)
gamma = wavelength
line spectrum
- each line on the emission spectrum corresponds to a specific electron transition
atomic emission spectrum
due to each element having electrons that can be excited to a different set of distinct energy levels
difference in energy between higher and lower energy states
E = hc / gamma = R_H [ (1/n1^2) - (1/n2^2)]
principal quantum number
- n
- first quantum number…
- larger the integer value of n, the higher the energy level and radius of the electron’s shell
maximum number of electrons within a shell:
2n^2
azimuthal quantum number
- letter l
- second quantum number, shape and number of subshells within a given principal energy level
- value of n limits value or l
- only possible values are 0 or (n-1)
spectroscopic notation
- l = 0 subshell is s
- l = 1 subshell is p
- l = 2 subshell is d
- l = 3 subshell is f
ex: n=4, 4d
maximum number of electrons within a shell
4l + 2
l = azimuthal quantum number
magnetic quantum number
- third quantum number
- ml
- specifies particular orbital within a subshell
- possible values of ml are the integers between -l and +l, including 0
spin quantum number
- fourth quantum number
- ms
- two spin orientations (+1/2) and (-1/2)
- two electrons in same orbital = opposite spin
Aufbau principle
- electrons fill from lower to higher energy subshells
(building up principle)
Hunds rule
- within a given subshell, orbitals are filled such that there are a meximum number of half-filled orbitals with parallel spins
