The elements of group 3 to 12 have their valence electrons in their outermost d subshells. These elements are called d block elements.

The elements of group 1 (except hydrogen) are metals. They react with water to form solutions that change the colour of a vegetable dye from red to blue. These solutions are said to be highly alkaline or basic. Hence they are called alkali metals.

a) K = 2, L = 8, M = 2
b) Group No.2, Period No.3

Every eighth element had properties similar to those of the first element like the eighth note in an octave of music is similar to the first.

The physical and chemical properties of elements are the periodic functions of their atomic masses

Elements which have the properties of both metals and non-metals are called as metalloids. (eg) Boron, Arsenic.

Alloys are mixtures of two or more metals and are formed by mixing molten metals thoroughly. Rarely nonmetals are also mixed with metals to produce alloys.

The last electron in these elements is filled in p subshells and hence these elements are called p-block elements. These elements are in group 13 to 18 in the periodic table.

Elements whose valence electron is filled in s subshell is known as s-block elements

Modern periodic law states that "The Chemical and Physical properties of elements are the periodic functions of their atomic number".