Electron Configuration
Chapter 5 Section 3
1. You need this to see!
Sodium + Titanium + Rhenium
2. You or me
Sulfur + Nitrogen + Phosphorous + Oxygen + Erbium
3. Vacation home
Calcium + Indium + Boron
4. Don’t gamble on this one!
Erbium + Polonium + Potassium
Electron Configuration

Electron Configuration – the arrangement of electrons in an
atom

Electrons tend to assume the arrangement that gives them
the lowest energy possible, due to the fact that low energy
systems are more stable

Three Rules to follow: Aufbau principle; Pauli exclusion
principle; and Hund’s Rule
Aufbau Principle

Each electron occupies
the lowest energy orbital
available
Pauli Exclusion Principle

A maximum of two
electrons can occupy a
single atomic orbital, but
only if the electrons have
opposite spins
Hund’s Rule

Single electrons with the
same spin must occupy
each equal-energy orbital
before additional electrons
with the opposite spin can
occupy the same orbital
Which of the following is correct?
Which of the following is correct?
Using the periodic table as a key
What block/energy level do the following
elements belong?
 Ru
 4d
O
 2p
 Br
 4p
 Cs
 6s
 Np
 5f
 Ar
 3p
What is the electron configuration for Be?
What is the electron configuration for N?
What is the electron configuration for
Mg?
What is the electron configuration for S?
What is the electron configuration for K?
What is the electron configuration for Ni?
Homework 10/27/14
 Do
the electron configuration for elements 1
– 18 in your notes.
Electron Configuration Notation

Designates the principal energy level, the energy
sublevel (associated with each orbital), and the
number of electrons in the sublevel

Sodium: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓
↑_
1s 2s
3s

2p
Sodium: 1s2 2s2 2p6 3s1
Write the Electron configuration notation
for the following:
 Zr
 Ce
 Ni
 Se
 Sr
HW: Using your homework from last
night write the notation for elements 1 –
18

H

Ne

He

Na

Li

Mg

Be

Al

B

Si

C

P

N

S

O

Cl

F

Ar
Noble Gas Notation

Noble gasses are the last column of the periodic
table

Full p-shells = Very stable

Noble Gas Notation uses bracketed symbols to
consolidate notation

Notation for Na: 1s2 2s2 2p6 3s1

Noble Gas Notation for Na: [Ne] 3s1
Noble Gas Notation
 Use
the Noble gas before the element you
are looking at
 Start
electron configuration after that noble
gas
 Example:
For Mo, Kr ends in 4p6 so you start
with 5s
 [Kr]
5s2 4d4
What is the noble gas notation for the
following:
 Bi
 Rb
V
 Si
 Ru