Question

Answer the following questions:

(a) What are alkali metals?

(b) Which Group and Subgroup are they placed in?

(c) What is their valency?

(d) Why do they not occur free in nature?

Answer 1

(a)

• Elements present in Group 1 of the periodic table except Hydrogen (H) are termed as alkali metals. It includes Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr).

(b)

• Elements present in Group 1, 2, 13 to 17 have a valence shell (outermost shell) not completely filled and are termed as normal elements or representative elements. These Groups lie in Subgroup A.
• Since alkali metals are present in Group 1 of the periodic table, they lie in the category of Subgroup A.

(c)

• Valence electrons in an element can be predicted by its group number. Example, elements in Group 1 have 1 valence electron.
• Valency of any element is the tendency of any element to accept or lose electrons to form a molecule with other element. Elements with valence electrons 1, 2, 3, and 4 have their valency 1, 2, 3, and 4 respectively.
• Since the alkali metals have one valence electron, their valency is also 1.

(d)

• Since alkali metals have only one valence electron, they will readily lose that electron to the other element to complete their octet (eight electrons in the valence shell). Hence, they are generally found in the combined state.