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Atomic structure review - H
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Thompson – discovered electrons
Rutherford – discovered the nucleus – small dense positive nucleus, volume empty space
Bohr – electrons have quantized (specific) energy, shell model
Heisenberg – due to wave nature of electrons you can’t know the position and momentum
of an electron at the same time
Pauli – no more than two electrons can occupy 1 orbital, that’s why a set of 4 quantum
numbers belongs to only 1 electron, when two electrons are in they differ in spin (the ms
quantum number)
Hund – each orbital in a sublevel partially fills before pairing up
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wavelength and frequency are inversely proportional
energy and frequency are directly proportional
hi energy light has high frequency and short wavelength
Isolelectronic means that species have the same number of electrons
Isotopes are species with the same number of protons and different numbers of neutrons
Mass number = protons + neutrons in a single atom
Atomic mass is a weighted average of all naturally occurring isotopes of an element, this
is the mass on the periodic table
Negative ions are atoms that have gained electrons
negative ions
Positive ions are atoms that have lost electrons
positive ions
Atoms are neutral
5 or more valence electrons become
3 or fewer valence electrons become
protons = electrons
Number of neutrons = mass number – atomic number
Valence electrons are all the electrons in the highest energy level
1s2 2s2 2p3 this is nitrogen in the ground state, it has 5 valence electrons
Dot structures show valence electrons only – all members of a group have the same dot
structure
Quantum numbers
The first number is the shell number
The second number is the sublevel s is 0 l is 1
d is 2
The second number must be less than the first !!!!!!!
f is 3
Each value of n (shell number) has that number of sublevels
1st energy level only has the s sublevel
2nd energy level has s and p sublevels
3rd energy level has s, p, d sublevels
4th energy level has s, p, d, f sublevels
S sublevel has 1 orbital (box)
P sublevel has 3 orbitals
D sublevel has 5 orbitals
F sublevel has 7 orbitals
After the 3 p orbitals are filled electrons go to 4s (K and Ca) then after 4s they go to 3d
For an element like Scandium which is 3d1 the 4s2 electrons are the valence electrons
1s22s22p63s23p63d14s2
Atomic number is the number of protons
Electrons are negative and massless
Electrons become excited by absorbing energy, they release that energy in the form of
light when the electrons return to lower energy levels (spectral lines)