Metals – Non—Metals & Metalloids
Metals – Non—Metals & Metalloids
On the basis of their properties, elements can be categorised as metals, non-metals and metalloids.
- An element that is malleable, ductile, and conducts electricity is called a metal.
- Gold, silver, iron, copper, tin, lead, sodium, and uranium are some examples of metals.
- Aluminium is the most abundant metal in the earth’s crust. Other major metals in the earth’s crust are iron, calcium, sodium, potassium and magnesium.
Important Properties of Metals | Metals – Non—Metals & Metalloids
- Metals are malleable, e., they can be beaten into thin sheets. Gold and silver are the most malleable metals.
- Next in the list are aluminium and copper. Silver foils are used for decorating sweets.
- Aluminium foils are used for packing chocolates, biscuits, medicines, cigarettes, etc. Aluminium and copper sheets are used to make utensils. Iron sheets are used to make a large variety of products, like boxes, buckets, tanks, etc.
- Metals are ductile, e., they can be drawn into thin wires.
- Gold and silver exhibit highest ductility, followed by copper and aluminium. Copper and aluminium wires are used in electrical wiring.
- Metals are good conductors of heat and electricity. Silver metal has been ranked as the best conductor of heat followed by copper and aluminium.
- That is why cooking utensils are usually made of copper or aluminium.
- Silver is the best conductor of electricity. Copper is the next best followed by gold, aluminium and tungsten.
- Electrical wires are, therefore, made of copper and aluminium. Iron and mercury have lower electrical conductivity.
- Metals are Gold, silver and copper have a shining surface and can be polished. They are used for making jewellery and decoration pieces.
- On keeping in air for a long time, metals lose their shine due to the formation of a layer of oxide, sulphide or carbonate due to the action of various gases present in air.
- Metals are hard except sodium and potassium, which are soft metals and can be cut with a knife.
- Metals are solids at room temperature. Mercury is an exception. It is the only metal which is a liquid at room temperature.
- Metals generally have high melting and boiling points. Exceptions are sodium and potassium which have low melting points.
- Melting points of gallium and caesium are so low that they start melting in hand.
- An element which is neither malleable nor ductile and does not conduct electricity is a non metal.
- Carbon, sulphur, hydrogen, oxygen, chlorine, and iodine are some examples of non-metals.
- Diamond and graphite are also non-metals. They are the allotropic forms of carbon.
- Carbon is a very important non-metal because carbon compounds like proteins, fats, carbohydrates, vitamins and enzymes, etc. are essential for the growth and development of living organisms. Metals – Non—Metals & Metalloids
- Oxygen is essential for breathing and combustion of fuels. Sulphur is present in hair, wool, onions and garlic.
- The major non-metals in the earth’s crust in the decreasing order of their abundance are oxygen, silicon, phosphorus and sulphur.
Important Properties of Non-Metals | Metals – Non—Metals & Metalloids
- Non-metals are They cannot be beaten into thin sheets or drawn into wires because of their brittleness.
- Non-metals are bad conductors of heat and electricity. Many non-metals are insulators. There are a few exceptions. For example, diamond is a good conductor of heat and graphite is a good conductor of electricity. Graphite is, therefore, used for making electrodes in dry cells.
- Non-metals are dull in appearance, i.e., they do not have lustre. Iodine is an exception. It has a shining surface like that of metals.
- Non-metals are quite soft. Carbon in the form of diamond is an exception. In fact, diamond is the hardest natural substance known.
- Non-metals can exist as solids (e.g., carbon, sulphur and phosphorus), liquids (e.g., bromine) and gases (e.g., hydrogen, oxygen, nitrogen and chlorine).
- Non-metals have low melting and boiling points, except graphite which has a very high melting point.
- Non-metals have many different colours. Sulphur is yellow, phosphorus is white or red, graphite is black, chlorine is yellowish green, bromine is reddish-brown, hydrogen and oxygen are colour less.
- Elements which show some properties of metals and some of non-metals, i.e., properties intermediate between those of metals and non metals, are called metalloids.
- For example, despite looking like metals, they are brittle like non-metals.
- Instead of being good conductors of electricity like metals or insulators like non-metals, they are semi-conductors.
- Boron, silicon and germanium are examples of metalloids. Metals – Non—Metals & Metalloids