Secondary Catalogue
Series: Periodic Classification of Elements
Characteristics of Groups: Atomic Size
The atomic size of an atom is the distance between the centre of its nucleus and its outermost electron shell. As we move down in a group, the atomic size of the elements increases gradually.
Characteristics of Groups: Valence Electrons and Valency
The groups in the Periodic Table are arranged vertically. There are 18 groups in the Periodic Table. All the elements in one group have the same electronic configuration and hence the same number of valence electrons and the same valency.
Characteristics of Periods: Valency
The valency of an element is determined by the number of valence electrons present in its atom. The valency of the element is calculated by the number of electrons lost or gained by its atom to achieve the nearest inert - gas electron configuration.
The Modern Periodic Table
The elements in the Periodic Table are roughly divided into metals, metalloids and non - metals. There are seven periods in the Periodic Table. The vertical columns in a Periodic Table are called groups and there are 18 groups in the Periodic Table.