Grade 9 Chemistry
Electronic Configurations and Atomic Structures
Objective:
● Deduce the pattern for determining the electronic configuration of the first 20
elements and draw their atomic structures
Electronic Configurations and Atomic Structures
Electrons move around the nucleus of the atom in specific areas called shells. Only electrons
with appropriate energy occupy a given shell. Each shell can accommodate a certain number
of electrons. The arrangement of electrons in an atom is known as electronic configuration.
This can be represented in writing using numbers or by drawing a shell diagram.
Arrangement of Electrons on Shells
● First Shell
-
2 Electrons
● Second Shell
-
8 Electrons
● Third Shell
–
8 Electrons (temporarily full)
Electronic Configurations for Elements 1- 20 of the Periodic Table
Copy and complete the Table
Elements
Number of Electrons
Hydrogen
1
Helium
2
Lithium
3
Beryllium
4
Boron
5
Carbon
6
Nitrogen
7
Oxygen
8
Fluorine
9
Electronic Configurations
1
2, 1
Neon
10
Sodium
11
Magnesium
12
Aluminium
13
Silicon
14
Phosphorus
15
Sulphur
16
Chlorine
17
Argon
18
Potassium
19
Calcium
20
2, 8
2 ,8 ,6
2, 8, 8
Atomic Structures
Diagram of potassium’ s Atomic Structure
Activity
Draw atomic structures for elements 1- 20 of the Periodic Table. Please
ensure that:
● Electrons on the first shell are paired (put them beside each other at the
top)
● Put the number of protons and neutrons in the nucleus in terms of
numbers e. g. 11p, 12n.
● Use x to represent the electrons.