Question

3) By observing the correlation in the first pair, complete the second pair: [2]
(1) Solid : Iodine : : ……………… : Bromine.
(2) Horizontal row : Periods : : …………………. : Groups .​

Answer 1

(1) Solid : Iodine : : Liquid : Bromine.

(2) Horizontal row : Periods : : Vertical columns : Groups .​

Explanation:

(1) The halogens are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine(Cl), bromine(Br), iodine(I), astatine(At). The artificially created element 117, tennessine(Ts), may also be halogen. This group is known as group 17.  

Halogens: Divers nature in their state.

Iodine & Astatine⇒ Solid

Fluorine & Chlorine⇒  Gas

Bromine⇒ Liquid

Solid : Iodine : :Liquid : Bromine.

(2) In the modern periodic table the elements are arranged from left to right as well as from top to bottom in accordance with their increasing atomic number.

• The horizontal rows which are present in the periodic table are known as periods. There are seven periods in the modern periodic table. The elements which are present in the same period will have an increasing order of the valence electrons.
• So this will increase the energy level of the atom so the energy sub-levels per energy level will also increase.
• While in the modern periodic table there are 18 vertical columns which are known as groups. So there are 18 groups in the periodic table. The elements which are present in the same group will contain a number of the valence electron configuration so they will have similar chemical properties.

Horizontal row : Periods : : Vertical columns : Groups .​