Elements on the Earth are classified into metals and non-metals based on their characteristics and physical properties. The periodic table has metals placed on the left while non-metals are placed on the right. Let us first look at what we mean by each of them.
What are metals?
Metals are solid materials and are typically hard, malleable (bendy), ductile (flexible) and heavy. They are good conductors of heat and electricity. Metals are shiny and have a high density. They can also be opaque as a thin sheet. Example: aluminium, copper, gold, silver, steel are all metals. Metals have one to three electrons in their outer shells.
What are non-metals?
Any material or substance that is not a pure metal is a non-metal. They do not have the properties of a pure metal. Non metals are dull in appearance. They are poor conductors of heat and electricity. Non-metals maybe solids, liquid or gases at room temperature. Non metals have four to eight electrons. Non metals are very good oxidising agents but they are very brittle and have low density. Example: hydrogen, helium, phosphorus, iodine, carbon are some non-metals.
Chemical properties of metals and non-metals
- Metals are very reactive. They tend to lose electrons very easily and form positively charged ions. This allows metals to form compounds with other elements very easily.
- Metals corrode easily. They are damaged by oxidation like rust or tarnish
- Almost all metal combine with oxygen to form metal oxide
- Metals like lead, copper, silver and gold do not recat with water at all
- Metals react with acid to give salt and hydrogen
- Non metals form oxides that are acidic in nature
- Non metals readily gain or share valence electrons
- Non metals gain electrons to form anions (an atom that has donated electrons, hence giving a negative charge)
Physical Properties of metals and non-metals
- Metals are hard except Sodium and Potassium
- The boiling and melting points of metals are high and they also have high density
- Metals are sonorous (when a metal is beaten it produces sound) except mercury
- Metals can be turned into thin sheets by hammering, this is called malleability
- Metals can be changed into thin wires, this is called ductile
- Non metals are soft- except diamond
- Non metals are mostly found in gaseous state, except Bromine which is found in liquid state
- Non metals have a dull surface except iodine and graphite
- Non metals are not sonorous