Question

What does the group number mean on the periodic table of elements?

Answer 1

Hint : A complex tabular format of all the existing chemical elements is known as periodic table. It is basically organised according to atomic number, its properties and electron setup. A group in a periodic table is a vertical column. There are a total $18$ groups numbered from left to right.

Complete Step By Step Answer:
If we observe the group number also represents valence electrons of elements in a group. Let's take an example of group one, they have one electron in its outermost shell. These valence electrons are involved in chemical bonds. Every element in the second group has two electrons in its outer shell as you keep counting the column you’ll know how many valence electrons are there. There are some exceptions when we consider transition elements. If we consider nitrogen its atomic number is seven, how many electrons are there in outer shell, it belongs to group five which tells us there are five electrons in outermost shell that mean there are two electrons in first shell and five electrons in outermost shell.

Note :
There are two different numbering systems that are commonly used. The traditional US system involves the use of $A$ and $B$ letter while numbering. The first two groups are $1A$ and $2A$ , the last six groups are from $3A$ to $8A$ . The middle groups are in $B$ s.