Electrons in Atoms
Electron Configuration
Orbital Notation
Lewis-Electron Dot Diagram
Essential question: What correlation is there between electron
configuration and orbital notation?
Essential question: What correlation is there between electron configuration
and orbital notation?
Electron Configuration

A form of notation which shows how the electrons
are distributed among the various atomic orbital and
energy levels
◦ Example of e- configuration for Hydrogen:
 1s1
Principle
Quantum
number which
stands for the
energy level
Total # of electrons in that
sublevel. 1st column of s-block
S-Block
Periodic Patterns




Yellow represents the s-block
Pink represents the p-block
Green represents the d-block
Orange represents the f-block
S-block
1
2
3
4
5
6
7
S-block
d-block
p-block
f-block
Learning Check

What element would have an electron
configuration ending in 4s1?
 Potassium
Order of filling sublevels


1s2 2s2 2p6 3s2 3p6 4s2
Sublevel (block)
# of orbitals
Maximum # of e-
S
1
2
p
3
6
d
5
10
f
7
14
You must fill in each sublevel with its maximum
number of electrons before you move to the
next energy level
Examples

e- configuration for Oxygen
◦ Oxygen has 8 electrons and is in period 2
◦ 1s2
2s2
2p4
2 energy
level and
located in
the p-block
6 valence
electrons
Practice

Write the e- configuration for the
following elements:
◦
◦
◦
◦
Helium
Neon
Sulfur
Calcium
Orbital Notation
Sublevel (block)
# of orbitals
Maximum # of e-
S
1
2
p
3
6
d
5
10
f
7
14
Every box represents an orbital
 Every arrow represents electrons

General Rules

Pauli Exclusion principle
◦ Every orbital can only hold 2 electrons with opposite
spins

Hund’s rule
◦ Within a sublevel, place one e- per orbital before
pairing them.
WRONG
Right
Example:
1s2

2s2
2p4
Orbital Notation for Oxygen:
◦ You know the e- configuration for oxygen is 1s22s22p4
◦ Remember:




Every orbital is represented by a box
Every orbital holds a maximum of 2 electrons
s-block represented by 1 orbital
p-block represented by 3 orbitals
Practice

Show orbital notation for the following
elements:
◦
◦
◦
◦
Helium
Neon
Sulfur
Calcium
Lewis Electron Dot Structure

An atom’s Lewis electron dot structure consists
of :
◦ element’s symbol-which represents the atomic
nucleus and inner-level electrons, surrounded by dots
representing the atom’s valence electrons.
Source: Glencoe Chemistry Matter and Change
pg. 140
Group 1A:
1 valence
electron
Group 2A:
2 valence
How do we
use
electrons
Group 3A: Group
Group
5A:
Group 6A:
Group
Group
7A:8A:
4A:
3 valence 4 5valence
valence
6 valence
7 valence
8 valence
electrons electrons
electrons
electrons
electrons
electrons
the periodic table to draw
Identifying
Lewis
electron the
dotrepresentative
structures? group
number will allow you to determine
the number of valence electrons.
Here’s how….
Writing out Lewis Electron Dot Structure

Group # = number of valence electrons

Example: Phosphorus is on group 5A, so it has 5
valence electrons.
Step 3: Continue placing one
Step 1: write the element
symbol
P
Step 2: Start at the top of
the symbol and place one
electron
electron on each of the four sides of
the symbol & then pair up the
electrons until you have placed all
valence electrons around the
symbol
Practice

Write the Lewis Electron Dot Structure
for the following elements:
◦
◦
◦
◦
Helium
Neon
Sulfur
Calcium
Questions??