Question

Four elements P, Q, R and S have atomic numbers 12, 13, 14, and 15 respectively. Answer the following

questions giving reasons :

i. What is the valency of Q ?
ii. Classify these elements as metals and non-metals.
iii. Which all elements form basic oxides.​

Answer 1

Answer:

valency of Q is 3(it is Al)

P AND  Q are  metals ...R ,S are  non metals

P ,Q form basic oxide.... rR weakly acidic....S stronly acidic

Explanation:

Answer 2

Answer :

i.

Electronic configuration of the given elements:-

1. P = 2,8,2
2. Q = 2,8,3
3. R = 2,8,4
4. S = 2,8,5

• Now, element Q has 3 valence electrons. Therefore, it needs to donate 3 electrons to become stable i.e., valency (Q) = 3.

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ii.

• We know metals are electropositive in nature and non-metals are electronegative in nature. Hence, any element that loses/donates upto 3 elements are metals and those elements which gains/receives or share upto 4 electrons are non-metals. In our question, elements P & Q will donate 2 & 3 electrons each. Hence, they are metals.

• On the other hand, elements R & S will share and accept 4 and 3 electrons each. Hence, they are non-metals.

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iii.

• We know metallic oxides are basic in nature. Then, we can say basic oxides are metallic. In our question, elements P & Q are metals. Hence, these two elements will form basic oxides.