Question

Name the elements which form water. How will you justify that water is a compound?

Answer 1

Hint: Compounds are chemical substances made up of two or more atoms of different elements that are chemically bound to each other in a definite ratio.

Complete step by step solution:
We know the formula of water is \[{{H}_{2}}O\,\,\].
The elements which form water are Hydrogen and Oxygen.
When two moles of diatomic hydrogen combine with one mole of diatomic Oxygen it gives two moles of water.
\[2{{H}_{2}}\,+\,{{O}_{2}}\,\to \,2{{H}_{2}}O\,\,\]
Now let's see why water is a compound.
It is made of two elements Hydrogen(H) and oxygen(O). As Hydrogen belongs to the 1st family of the periodic table and has one electron in the outermost shell (Valence shell) and Oxygen belongs to the 6th family of the periodic table and has 6 electrons in the outermost shell. These two want their valence shell to be complete, in order to do so they distribute their electrons and form a covalent bond. In this case oxygen needs 2 electrons and hydrogen can give only one, so two hydrogen combines with one oxygen atom to give a molecule of water which is a compound as the elements are chemically bonded.
Water is a molecule which consists of elements \[{{H}_{2}}\] and \[{{O}_{2}}\] in a definite ratio 1:8 (by mass).
The elements present in a water molecule (Hydrogen and Oxygen) have different properties as compared to the compound that is \[{{H}_{2}}O\,\,\].
Hydrogen is a combustible gas and oxygen is a supporter of combustion which is entirely different to the compound of water which is a liquid.
Water isn't a mixture, it's bonded chemically so it can not be separated by physical means.
From the above points we can conclude that water shows all the properties of a compound. Hence, it is a compound.

Note: Water molecule has polarity that means it has slight negative charge on Oxygen atom and partial positive charge on Hydrogen atom which attracts another water molecule at its end.
It has some other properties too like Cohesion, Surface tension and specific heat.
It has a boiling point of $100^o$C.