EVERYDAY SCIENCE

Detailed explanation-1: -The physical and chemical properties of elements depend on the number of valence electrons. Elements present in the same group have the same number of valence electrons. Therefore, elements present in the same group have similar physical and chemical properties.

Detailed explanation-2: -The elements in the same group have similar chemical properties because they have the same valence shell electron configuration. The elements in a row show a gradual change in chemical properties because their valence shell electron configuration changes gradually along the row.

Detailed explanation-3: -The elements in the same group have a similar number of valence electron. They have an identical number of electrons in their outermost shell. e.g. All the alkali metals in Group 1 have 1 valence electron, so they all tend to react the same way with other substances.

Detailed explanation-4: -The elements in each group have the same number of valence electrons. As a result, elements in the same group often display similar properties and reactivity.

Detailed explanation-5: -The elements of a group have similar chemical properties but in a period they have different chemical properties. This is because the chemicals properties depend on no of valence electrons.