1.19 Predict the electronic configurations of the first 20 elements

Question 1

What does the electronic configuration of an element indicate?

Answer 1

It tells you how many electrons are in each shell around an electron’s nucleus.

Question 2

How many electrons does sodium have?

Answer 2

Sodium has 11 electrons: 2 in its most inner shell, then 8, then 1 in its outermost shell.
Sodium’s electronic configuration can be represented as: 2.8.1.

Question 3

How can sodium’s electronic configuration be represented?

Answer 3

It can be represented as 2.8.1 or in a diagram.

Question 4

What does the group of an electron indicate?

Answer 4

The group an electron is in tells you how many electrons are in its outermost shell.
For example, group 1 elements have 1 electron in their outer shell.

Question 5

What does the period of an electron indicate?

Answer 5

The period an electron is in tells you which number shell an element’s outermost electron is found in.
For example, period 3 elements have their outermost electrons in shell 3.

Question 6

How many electrons can the first shell hold?

Answer 6

The first shell can hold 2 electrons.
For shells 2 and 3, they can hold 8 electrons each.