Question

A substance $X$ on heating gives $Y$ and $Z$ . What is $X$ ? Is it an element or a compound? state two differences between an element and a compound.

Answer 1

Hint: Compare the type of reactions that Compounds undergo and the type of reaction elements will undergo. Elements are made up of only one type of atom whereas Compounds are made up of two or more than two types of atoms.

Complete step by step solution:
Let us start by understanding the terms in the question. An Element is a species which is made of only one type of atom. They cannot be broken down further chemically. They are Monatomic species which means they are made up of the same type of atoms. For example: ${Na}(Sodium),He(Helium)$ A compound is made of one or more than one type which is formed by chemical bonds. They can be broken down further into their simpler units. They are heteroatom species which means that they are made of different atoms. For example: $NaCl(Sodium\,Chloride),{H_2}O(Hydrogen\,dioxide)$ Let us write the above question in a reaction form: $X\xrightarrow{\Delta }Y + Z$ From this, the information we get is, $X$ breaks down or undergoes decomposition when heated to give $Y$ and $Z$, which are two separate species. This is only possible if $X$ is made of two separate species $Y$ and $Z$ have been derived from those species. An element cannot be made of two separate species as we have discussed. Hence $X$ is a compound. The differences between elements and compounds is given below:

Element	Compound
They are pure chemical substance which means they are made of a single type of atom	They contain different atoms which are bonded together chemically.
They can be represented with symbols. For example, ${Na}(Sodium),{O_2}(Oxygen),He(Helium)$	They are represented through a molecular formula. For example: $NaCl(Sodium\,Chloride),{H_2}O(Hydrogen\,dioxide)$

Note:
Elements are finite as there are only 118 elements in the periodic table, whereas there can be many possibilities of chemical bonds between different elements to form compounds. Both elements and compounds are pure substances .