EVERYDAY SCIENCE

Detailed explanation-1: -Valency of an element determines its chemical reactivity. Therefore, for all elements belonging to a particular group in the periodic table, the number of electrons in the outermost shell, that is the valence electrons will be the same. Hence, all the elem in that group will show the same chemical reactivity.

Detailed explanation-2: -The number of electrons in the outermost shell of an atom determines its reactivity.

Detailed explanation-3: -For neutral atoms, the number of valence electrons is equal to the atom’s main group number. The main group number for an element can be found from its column on the periodic table. For example, carbon is in group 4 and has 4 valence electrons. Oxygen is in group 6 and has 6 valence electrons.

Detailed explanation-4: -The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive. Lithium, sodium, and potassium all react with water, for example.