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Periodic Table: Classifications of Groups.

    • Metals: this is a term that is heard very commonly. Gold, silver, iron, aluminum which we use in our daily life are metals. How can you say that a particular element is a metal or not? The answer is basing on the some of the common properties that are defined for metals.

      Properties exhibited by metals: when we talk about the properties your immediate answer will be metals are lustrous. Right! Other properties of metals include malleability i.e. they can be turned into desired shape by hammering and ability to conduct heat and electricity. Conductivity of metals is due to the presence of lone pair of electrons in the outer orbitals.
      There are a great number of metals. To ease their study of properties, they are further classified in to alkali metals, alkaline earth metals and transition metals. Transition metals are further classified into lanthanides and actinides.
      • Alkali metals: elements of the group IA (group 1) are termed as metals. Due to their high ability to react, they form salts and many other compounds. They are light metals. When compared to other atoms in that period they are the largest of all the atoms. Ions of these metals have a +1 charge. Examples include sodium and potassium.
      • Alkaline earth metals: elements of group II A (group 2) are termed as alkaline earth metals. They are smaller in size compared to alkali metals. They are also highly reactive and can form many compounds. Ions of this group have +2 charge.
      • Transition metals: elements from I B to VIII B (groups 3 to 12) are termed as transition metals. Elements of these groups show high melting and boiling points and are very hard. Like alkali metals they are malleable and conduct heat and electricity. As there are many elements in this group, they are further classified into smaller groups namely lanthanides and actinides. These two blocks of elements are located at the bottom of the periodic table. Another classification adopted for transition metals is triads. Triad is a group of three elements that are closely related to each other. For example, iron, cobalt and nickel form one triad and is named as iron triad.

      • Lanthanides: when you observe the periodic table, you can find two rows at the bottom of the table. The elements of the top row that start with lanthanum are termed as lanthanides. These are soft metals with high melting and boiling points. They lose their luster very easily. These metals are mainly used in lamps, magnets and lasers. They are also used as boosters to improve the properties of other metals.
      • Actinides: A row of elements that exist just below the lanthanides are termed as actinides. The starting element of this group is actinium. Elements of this group are mainly radioactive. Due to unique radioactive property, they are greatly used in medicines and in nuclear reactions.
      Elements of these two groups exhibit oxidation states of either +3 or +4 or +2. But, +3 is the most commonly observed state.
    • Nonmetals: non metals are those without the properties of metals. They can be said to have properties that are quite opposite to that of metals. They include poor ability to conduct electricity and heat, and are brittle.

      Non metals are categorized into two groups. They are the noble gases (group 17) and halogens (group 18).
      • Halogens: examples of halogens include chlorine, fluorine and iodine. These are found as components of disinfectants, bleaches and salts. Unlike metals they form ions with -1 charge. These are highly reactive compounds as they are in search of attaining the octet configuration.
      • Noble gases: examples of noble gases include neon, argon and helium. These are very stable due to the presence of octet configuration. Hence, they do not love to either gain or lose electrons. These are used in refrigerants and lasers.
      Hydrogen is also a non metal as it does not act like a metal.
    • Metalloids: Metalloids are those with properties of both metals and non metals. The existence of these compounds is because of the transition of the metals into non metals. Groups 13-15 are a clear indication of this transition. They contain a mixture of metals, non metals and metalloids.

      This way of categorizing the elements helps to predict the properties of the elements as we move across or down the periodic table.