Most elements are metals. On the periodic table, metals are separated from non-metals by a zig-zag line stepping through carbon, phosphorus, selenium, iodine and radon. These elements and those to the right of them are non-metals. Elements just to the left of the line may be termed metalloids or semimetals and have properties both of metals and non-metals.
Non - Metals
Non-metals are the elements in groups 14-16 of the periodic table. Non-metals are not able to conduct electricity or heat very well. As opposed to metals, non-metallic elements are very brittle, and cannot be rolled into wires or pounded into sheets. The non-metals exist in two of the three states of matter at room temperature: gases (such as oxygen) and solids (such as carbon). The non-metals have no metallic lustre and do not reflect light. They have oxidation numbers of ±4, -3, and -2.
The physical and chemical properties of the metals and non-metals:
Metal Physical Properties:
- Lustrous (shiny)
- Good conductors of heat and electricity
- High melting point
- High density (heavy for their size)
- Malleable (can be hammered into sheets)
- Ductile (can be drawn into wires)
- Usually solid at room temperature ( mercury is an exception)
- Opaque as a thin sheet (can't see through metals)
- Metals are sonorous, they make a bell-like sound when struck
Non-metal Physical Properties
- They are not lustrous (dull appearance)
- They are poor conductors of heat and electricity
- Non-ductile solids
- Brittle solids
- They may be solids, liquids or gases at room temperature
- nonmetals are not sonorous
Metal Chemical Properties
- They have 1-3 electrons in the outer shell of each metal atom
- They corrode easily (e.g., damaged by oxidation such as tarnish or rust)
- They easily lose electrons
- They form oxides that are basic in nature
- They have lower electro-negativities
- They are good at reducing agents
Nonmetal Chemical Properties
- Usually have 4-8 electrons in their outer shell
- They readily gain or share valence electrons
- They form oxides that are acidic in nature
- They have higher electro-negativities
- They are good oxidizing agents
- Metallurgy is the science of extraction of metals from their ores and their purification.
- Minerals are naturally occurring substances containing one or more elements or their compounds.
- Ore is a mineral from which one or more metals can be extracted profitably.
- Metallurgical processes:- It consists of three main steps. They are
i) The concentration of the ore ii) Reduction iii) Refining
- The concentration of the ore:- It is the removal of impurities from the ore.
- Reduction:- it is the process of obtaining the metal from its compound.
- Refining:- is the process of purification of impure metals to obtain pure metal.
Uses of metals:-
- Iron: Used for making pins, nails, nuts, bolts, tools, machines, construction of buildings, bridges etc.
- Aluminium: Used for making utensils, wires, furniture, parts of aircraft, vehicles, machines, for packing food and medicines etc.
- Copper: Used for making wires, vessels, electric gadgets etc.
- Gold: Used for making jewellery, coins medals etc
- Silver: Used for making jewellery, Coins, medals etc.
- Platinum: Used for making jewellery, electric gadgets, plugs in vehicles etc.
- Sodium: Compounds are used as common salt, chemicals etc.
- Calcium: Compounds are used for making cement, glass etc.
Uses of non-metals:-
- Sulfur: Used for making sulphuric acid, salts of metals etc.
- Oxygen:- Used for respiration by living things, burning of fuels etc.
- Nitrogen:- Used for making ammonia which is used for making fertilizers.
- Hydrogen:- Used for making ammonia which is used for making fertilizers, as fuel in rockets, for welding etc.
- Chlorine:- Used as an antiseptic, to kill germs in the water.
- Iodine:- Used as tincture iodine which is an antiseptic.