Answer» - 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.
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