(a) How does metallic character of elements in Modern Periodic Table vary on moving from(i) left to right in a period?(ii) top to bottom in a group?Explain with the help of an example in each case.(b) If an element X is placed in group 14, what will be the nature of bond in its chloride? Write the chemical formula of the compound formed.(c) An element X has mass number = 35 and number of neutrons = 18. What is the atomic number of X ? Write electronic configuration of X and determine its valency.

Academic Chemistry NCERT Class 10

(a) (i) On moving from left to right on the period table, the metallic character decreases because atoms more readily accept electrons to fill a valence shell than lose them to remove the unfilled shell.

Example: Na (Sodium) is more metallic than Zn (Zinc).

(ii) Metallic character increases on moving down an element group in the periodic table because electrons become easier to lose as the atomic radius increases, where there is less attraction between the nucleus and the valence electrons because of the increased distance between them.

Example: K (Potassium) is more metallic than Li (Lithium).

(b) Element X is placed in group 14, so it will have 4 valence electrons. So it will form chloride with the chemical formula XCl₄ and it will form covalent bonds.

(c) Mass number of X = 35

Number of neutrons = 18

Atomic number = Mass number – Number of neutrons

= 35 – 18 = 17

Therefore Atomic Number of X= 17

Electronic configuration of X = 2, 8, 7

Group of X = 17

Period of X = 3

Valency of X = 1.

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Updated on: 10-Oct-2022

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