Question

An element in period 3 which does not form an oxide:
A. Na
B. Al
C. Ar
D. Cl

Answer 1

Element is defined as a species of atoms in which all the atoms are having the same number of protons in the nucleus. Oxides are the oxygen containing compounds or the binary compounds of oxygen which are reacted with lesser electronegative elements so that oxide can form. The oxides are generally classified on the basis of structure of the oxide, oxidation state and nature of oxide.

Complete answer:
To approach this question we need to know the products formed on the oxidation of these compounds. The elements will not react with oxygen when they have attained noble gas configuration.

Now on reaction of sodium with oxygen we see that the formation of sodium oxide takes place. The sodium oxide is a strongly basic oxide which tends to react with hydrogen to form sodium hydroxide as the sodium oxide is an unstable compound. The reaction of sodium and oxygen is the following:
$4Na+{{O}_{2}}\to 2N{{a}_{2}}O$

Now when Al that is aluminium is reacted with oxygen again the formation of aluminium oxide takes place. The reaction for same is the following:
$4Al+3{{O}_{2}}\to 2A{{l}_{2}}{{O}_{3}}$

When Ar or argon is not able to react with the oxygen because it has attained its noble gas configuration as its valence shell is completed so it will not react with oxygen because it is extremely stable and so it doesn’t lose or gain electrons. As on reacting with oxygen it would disturb or unstable the configuration of Argon so it will not react with oxygen. Now in option d when chlorine is reacted with oxygen the formation of nascent oxygen and chlorine oxide takes place. The reaction is the following:
$Cl+{{O}_{2}}\to ClO+[O]$

So the inert gas Ar is not able to make oxide. So the answer is option C.

Note: the different types of oxides are acidic oxide, basic oxide, amphoteric oxide and neutral oxide. The acidic oxide is formed when non metal reacts with oxygen. The basic oxide is formed when metal reacts with oxygen. The amphoteric oxide has both basic and acidic nature. The neutral oxide is the oxide which has neither acidic or basic nature.