Number that specifies the properties of the atomic orbitals
Tells us the distance from the nucleus and the shape of the orbital
Quantum Number
Electron Configuration
Main level or shell These are the Bohr energy levels
n = 1, n = 2, n = 3 As n increases, the distance from the
nucleus increases
Principal Quantum Number
Each main level is divided into sublevels Four types of sublevels
spdf
Sublevel
Each sublevel is made of orbitals Every orbital can hold 2 electrons
Orbital
s – 1 orbital – 2 electrons p – 3 orbitals – 6 electrons d – 5 orbitals – 10 electrons f – 7 orbitals – 14 electrons
S orbital One spherical
shaped orbital
P orbitals
Three dumbbell shaped One dumbbell in each axis
P Orbitals
D orbitals (5)
F orbitals (7)
Main Level Sublevels Number of Sublevels
Electrons in sublevels
Total Electrons in Main Level
1 s 1 2 2
2 sp
13
26
8
3 spd
135
26
1018
4 spdf
1357
26
1014
32
Arrangement of electrons in an atom Aufbau Principle – electrons fill into an atom
starting with the lowest energy levels
Electron Configuration
Way which the electrons rotate on their axis Pauli Exclusion Principle – in order for two
electrons to occupy the same orbital, they must have opposite spin
Electron Spin
Orbital Diagram
Hund’s Rule – electrons occupy orbitals singly first before doubling up
Write the configuration for each of the below
CSBrNaClKr
Writing Configurations
Valence Electrons Electrons in the last main energy level These are the electrons farthest out on the
atom These will interact with other atoms These are the electrons involved in
chemical reactions There are a maximum of 8 valence
electrons
How to find valence e- Write configuration and count electrons in
last main energy level Examples: Find valence electrons for
CNaPFeAr
Atoms will give up, accept, or share electrons in order to achieve a filled valence shell (8 valence electrons)
Octet Rule
Metallic Character Metals become more reactive (more
metallic in character) as you go down a group
Most metallic elements bottom left corner of the periodic table
Least metallic, top right corner
Ionization Energy Energy required to remove the most
loosely held electron from an atom The greater the ionization energy, the
more strongly the atom holds onto its electrons
M + energy → M+ + e Ionization energy increases as moving
across a period Ionization energy decreases as moving
down a group
Atomic Radius Half of the distance between two adjacent
nuclei Radius decreases across a period (atoms
hold the electrons tightly in) Radius increases down a group