Question

how many valence electrons are in each of the following elements? Express your answer as an integer.

1.) O

2.) S

3.) Br

4.) Rb

Answer 1

Valence electrons are the electrons that are found in the outer energy level. These are capable of taking part in interactions and thus, are useful for studying chemical properties.

The number of valence electrons in an element can be obtained by referring to it's group number,

For group 1 and group 2, the number of valence electrons equals 1 and 2, respectively,

And for group 3 to 12, the number of valence electrons equals 3 to 12, respectively.

And as for group 13 to 18, the number of valence electrons 3 to 8, respectively.

In the given problem,

a.) O

Oxygen is a group 16 element, therefore, it's number of valence electrons = 6

b.) S

Sulphur is just below oxygen in periodic table, and thus, belong to the same group. Therefore, it's number of valence electrons = 6

c.) Br

Bromine is a group 17 element, therefore, it's number of valence electrons = 7

d.) Rb

Rubidium is a group 1 element, therefore, it's number of valence electrons = 1