An element's group number tells you how many the element has.

An element's group number tells you how many valence electrons the element has.

Explanation:

In the periodic table, each element is placed in a specific location because of its atomic structure.

The elements are arranged in rows,  called a period. All of the elements in a period have the same number of atomic orbitals.

The elements are also arranged in vertical columns. Each column is called a group. The elements in each group have the same number of electrons in the outer orbital. These electrons are called as valence electrons.  Example: Group 1 elements have 1 valence electron each.

1 a

2 d

3 a

4 c

explanation: