Question

(a) Explain the terms ‘metal’. ‘nonmetal’, and metalloid' giving two examples of each

(b) Classify the following as metals, nonmetals, and metalloids:

Hydrogen, sodium, potassium, gold, bromine, carbon, silicon, mercury, sulphur, phosphorus

Answer 1

Elements can be classified into metals, nonmetals, and metalloids depending upon the properties-

Metals

• Metals are generally hard but exceptions are there sodium and potassium which are soft.
• Metals have shiny surface i.e.., lustrous.
• Metals are malleable. i.e.., we can make sheets out of them when hammered.
• Metals are ductile. i.e., they can be drawn into wires ( copper wire is a good example).
• Metals are good conductors of heat and electricity.
• They can produce ringing sound when struck. i.e., sonorous.
• Examples: Copper$\left(\mathrm{Cu}\right)$, Silver$\left(\mathrm{Ag}\right)$.

Nonmetals

• Nonmetals are generally soft but diamond is an exception which is the hardest material.
• Nonmetals have non-shiny surface, i.e nonlustrous.
• Nonmetals are nonmalleable, i.e we can not make sheets out of them when hammered.
• Nonmetals are nonductile, i.e they can not be drawn into wires.
• Nonmetals are bad conductors of heat and electricity but exception is there graphite which is a good conductor of electricity.
• They can not produce ringing sound when struck. i.e.,nonsonorous.
• Example: Carbon$\left(\mathrm{C}\right)$, Oxygen$\left(\mathrm{O}\right)$.

Metalloids

• Elements which show character (properties) in between metals and nonmetals are categorised as metalloids.
• The appearence is similar to that of metals.
• They are generally brittle, i.e hard but can easily break.
• Example: Boron$\left(\mathrm{B}\right)$, Silicon$\left(\mathrm{Si}\right)$.

(b) By analysing the properties of metals, nonmetals and metalloids, we can classify the elements into

Metals: Sodium$\left(\mathrm{Na}\right)$, Potassium$\left(\mathrm{K}\right)$, Gold$\left(\mathrm{Au}\right)$, Mercury$\left(\mathrm{Hg}\right)$ (a metal which is in liquid state).

Nonmetals: Carbon$\left(\mathrm{C}\right)$, Sulphur$\left(\mathrm{S}\right)$, Phosphorus$\left(\mathrm{P}\right)$, Bromine$\left(\mathrm{Br}\right)$.

Metalloids: Silicon$\left(\mathrm{Si}\right)$.