Question

How could you distinguish between elements from its compound?

Answer 1

We generally distinguish between elements on the basis of their physical and chemical properties, so for distinguishing elements and their compound we use the same. We can distinguish between their physical and chemical properties like for example color and state- it is a physical property and always there is a difference in their color and state.

Complete step by step answer:
We have many elements in our periodic table which are arranged in increasing atomic numbers. This includes some periodic trends, like atomic radii - it means that there is an increase in atomic radii on moving down the group or decrease in atomic radii on moving left to right. Similarly there is another property called electronegativity. It is that attraction force by which a shared pair of electrons get attracted on one side of a bond. So the trend is, it increases when we move from left to right , from hydrogen to neon side. So many compounds formed on the basis of electronegativity difference and also by the tendency to donate electrons or accept electrons.

It is clear when two or more elements combine they form a compound, as the name suggests that it will form by combination. This combination takes place when the elements are in some molar ratio. Elements have their particular position in a periodic table where they stand with appropriate values of electronegativity, electron gain enthalpy etc. They have their proper physical properties and chemical properties, here chemical property is the reaction they show with different compounds.

Let’s take an example of magnesium oxide $MgO$ , it is a compound i.e. it is formed by combining magnesium $Mg$ and oxygen ${O_2}$ . Physically this process takes place when magnesium ribbon is burned in excess of oxygen, a greyish ash is produced. Now the question arises that how will we differentiate between them so firstly magnesium element is a solid of silvery white color while greyish ash produced are of magnesium oxide. Chemical properties of both are almost different, magnesium ribbon when dropped in water burns vigorously while magnesium oxide when mixed with water gives magnesium hydroxide and this reaction gets reversed when we apply heat.

Note: Physical properties like color, shape, odour (smell) are different for element and its compound. Similarly chemical properties are also different like their boiling point, melting point etc. You can take an example of water which is formed by the combination of two gases hydrogen and oxygen.