Question

Classify the following into element, compound and mixture:

Silicon

Answer 1

Silicon $\left(\mathrm{Si}\right)$ can be classified as an element.

• This is because silicon is made up of silicon particles (i.e.; atoms).
• In the sense that silicon contains only one type of constituent particles i.e.; silicon atoms, it is a pure substance.
• Silicon atoms cannot be broken down into simpler substances.

It is not a compound because there is no combination of two or more substances as only one substance is present and that is silicon only.

• Similarly, it is not a mixture due to the presence of only one substance.

Element: An element is a pure substance that cannot be split into simpler substances.

• Example: Hydrogen $\left({\mathrm{H}}_2\right)$, Copper $\left(\mathrm{Cu}\right)$ etc.

Compound: A compound is a pure substance in which elements combine chemically in a fixed composition to give a compound.

• They can be broken down into elements that make up the compound by using chemical or electrochemical methods.
• The properties of the compound are entirely different from the elements from which it is formed.
• Example: Water $\left({\mathrm{H}}_2\mathrm{O}\right)$, Common salt i.e.; Sodium chloride $\left(\mathrm{NaCl}\right)$

Mixture: When two or more substances (elements or compounds or an element and compound) are mixed in any proportion.

• The components of a mixture can be separated by physical methods of separation.
• Example: A mixture of Sand and Iron $\left(\mathrm{Fe}\right)$ can be separated by using a magnet (physical process) where Iron gets attracted to the magnet leaving behind sand.