Question

Explain about the structural features of Moseley’s long form of periodic table.

Answer 1

• The long form of periodic table of the elements is constructed on the basis of modem periodic law. The arrangement resulted in repeating electronic configurations of atoms at regular intervals. 
• The elements placed in horizontal rows are called periods and in vertical columns are called groups. 
• According to IUPAC, the groups are numbered from I to 18. 
• There are 18 vertical columns which constitute 18 groups or families. All the members of a particular group have similar outer shell electronic configuration.
• There are 7 horizontal rows called periods.

Period number	Number of elements
1	2
2	8
3	8
4	18
5	18
6	32
7	19 (incomplete)

The elements are shown in the above table along with its atomic numbe. 

• The atomic number also indicates the number of electrons in the atoms of an element. 
• This periodic table is important and useful because we can predict the properties of any element using periodic trend, even though that element may be unfamiliar to us.