A. Elements are classified as metals, non metals or metalloids based on the properties which they exhibit.
1. Metals are those elements which are hard, opaque and shinny in nature and they are good conductor of heat and electricity. During chemical reactions, metals give away one or more electrons in order to attain stability.
Metals are malleable and ductile. Most metals are solid but some are liquid, for example mercury. Examples of solid metals are sodium, potassium, lead, zinc, etc.
2. Non metals are those elements which do not have the properties of metals. During chemical reactions, non metals accept electrons from metals. Non metals are also poor conductor of heat and electricity but they serve as good insulators. Non metals are not as lustrous as metalloids and most of them are gases. Examples are: chlorine, bromine, oxygen, nitrogen, fluorine, etc.
3. Metalloids have properties that are in-between that of metals and non metals. Metalloids are solid, have metallic appearance and can conduct electricity to some extent but not as good as metals. They have higher densities compared to non metals. Mettaloids are brittle in nature while metals are ductile and malleable. Examples are: boron, silicon, antimony, etc.
B. The periodic table is divided into 18 groups. A group refers
to a column of elements in the periodic table. All the elements in the same
group share the same chemical and physical properties. Some of the groups are
given specific names while the rest are identified by the first element in that
group. The groups with specific names are as follows:
Group 1: Alkali metals
Group 2: Alkali earth metals
Group 11: Coinage metals
Group 15: Pnictogen
Group 16: Chalcogens
Group 17: Halogens
Group 18: Noble gases.
