Question

The atomic numbers of two elements A and B are 11 and 12 respectively. Which element exhibits the highest metallic property ? Write the molecular formula of the compounds formed when these elements combine with the element ‘Z’ having atomic number $8$.

Answer 1

Hint: We know that we can identify the given elements by their atomic number with the help of a periodic table. We can compare the metallic properties of elements with the help of trends of periodic tables. So let's identify the elements first.

Step-By-Step answer:
So the elements with atomic numbers $11$ and $12$ are sodium and magnesium respectively and the element having atomic number $8$ is oxygen. We know from the trends of periodic table that metallic character decreases across a period so sodium exhibits higher metallic character than magnesium.
When sodium is heated and then put it in a jar full of oxygen it produces a lot of energy and heat. After the reaction sodium oxide with chemical formula $N{a_2}O$ is left over in the jar in the form of white powder. Magnesium metals burn very easily in air. When magnesium reacts with oxygen it forms magnesium oxide with molecular formula $MgO$. This is an exothermic reaction where energy releases during the reaction.
Hence the molecular formula of the compounds formed when elements A and B which is $Na$ and $Mg$ reacts with the element ‘Z’ having atomic number $8$ which is oxygen are $N{a_2}O$ and $MgO$.

Note: Sodium and magnesium are very electropositive elements and oxygen is electronegative. Electropositive elements often form salt with electronegative elements. $N{a_2}O$ and $MgO$ are basic oxides. It takes more energy to break these oxides as they are held by strong attractions. $MgO$ is also known as magnesia which is a white hygroscopic mineral. $N{a_2}O$ is used in ceramics and glasses. Magnesium oxide is used in treatment of indigestion or as a laxative to relieve occasional constipation. It is also used as a supplement to maintain adequate magnesium in the body.