Question

The element with atomic number $ 14 $ is hard and forms acidic oxide and a covalent halide. To which of the following categories does the element belong?
a) Metal
b) Metalloid
c) Non-metal
d) Left –hand side element

Answer 1

Hint: In the periodic table, the metals lie on the left hand side and the nonmetals and metalloids lie on the right hand side conventionally. On moving down the group the metallic character increases which increases the basicity of the metal oxides.

Complete step by step solution:
In the periodic table, the element with atomic number $ 14 $ is identified as Silicon.
Silicon belongs to the $ {14^{th}} $ group and period number is $ 3 $ . It belongs to the carbon- family of P-block elements.
The electronic configuration of silicon can be represented as $ 1{s^2}2{s^2}2{p^6}3{s^2}3{p^2} $ . The stable oxidation states of these elements are $ + 2 $ and $ + 4 $ .
The $ {14^{th}} $ group lies at the right hand side of the periodic table. We know that the right side of the periodic table mostly has nonmetals and metalloids and the left side of the periodic table has metals.
As we move from left side to right side in a group, the metallic nature of the element decreases.
The oxides of metals are generally basic in nature as when they react with water they form a basic solution due to the formation of a base.
 $ MO + {H_2}O \to M{(OH)_2} $ Where $ M $ represents the metal of group 2. The metal hydroxide formed gives hydroxide ions in water and thus are basic in nature.
But when oxides of non-metals react with water they form acidic solutions. The general reaction of carbon group can be represented by
  $ M'{O_2} + {H_2}O \to {H_2}M'{O_3} $ Where $ M' $ represents the non-metals of the group $ 14 $ . The acid formed provides $ {H^ + } $ ions in the solution which lowers the $ pH $ .
In the carbon family, carbon and silicon are the non-metals whereas germanium is metalloid, tin and lead are pure metals. This effect is seen when we move down the group, as the metallic property increases.
The halides of this group are typically covalent as the electronegativity difference between atoms is not too high to be an ionic bond.
Thus the correct option is (c).

Note:
The bond formed between nonmetal and halide ions has a shared pair of electrons. The shape is tetrahedral and they are very volatile. The silicon-fluorine, silicon-chlorine bond that is formed is exceptionally strong as compared to carbon because silicon has $ d $ orbitals, which helps in the stronger $ p\pi - d\pi $ bonding.