Non Metals

Non Metals

Non-Metals are electronegative elements and tend to share or accept electrons in a chemical reaction. According to physics, non-metals can be defined as elements with a high band gap (activation energy). They are good insulators of heat and electricity. They are mostly gases and sometimes liquid. In addition, non-metals lack luster and have four or more than four electrons in their valence shell. Of all the elements known, 20 have been found to have non-metallic properties.

Physical Properties of Non-metals

1. Non-metals have more than four electrons in their outermost shell, which makes them highly electronegative. This electronegativity confers a negative charge on the non-metal ion during ionic bond formation.

2. On moving from left to right in a periodic table, the non-metallic property increases due to the addition of electrons in the valence shell; this also causes a decrease in atomic radii across the period.

3. Non-metals are amorphous and brittle in nature.

4. As these elements have a high band gap, the amount of activation energy required by the electrons to enter the conduction band is relatively high, which is generally impossible to achieve, and so these elements act as insulators and bad conductors of heat. (Exception: Graphite, an isotope of carbon) Non-metals lack the metallic properties of luster, malleability, and ductility.

5. Unlike metals, non-metals do not produce any sound on hitting a surface and hence can be called non-sonorous.

6. Non-metals at room temperature and under standard conditions of pressure can exist as either solids or gases. (Exception: Bromine)

7. Non-metals can exist as monoatomic, diatomic, and polyatomic molecules. Some elements also have allotropic forms.

Chemical Properties of Non metals

1. The reaction of non-metals with metals Metals and non-metals together undergo a redox reaction in which the metal gets oxidized while the non-metal is reduced. The ultimate product has both metallic and non-metallic ions held together by an ionic bond.

2. In an aqueous solution of sodium hydroxide and hydrochloric acid, the dissociated ions sodium (metal) and chlorine (non-metal) undergo a redox reaction to form sodium chloride (salt).

3. Non-metals in the presence of oxygen can undergo oxidation reactions to form acidic or neutral oxides.

4. Carbon on reaction with oxygen can form two compounds; carbon monoxide and carbon dioxide.

5. The non-metallic oxide can also react with water to form acids. Example: Carbon dioxide on reaction with water forms carbonic acid. Similarly, sulfur dioxide on reaction with water can form sulphuric acid.

6. Non-metals do not react with acids, as they themselves are acidic in nature. However, non-metals can react with bases to form various salts and water.

7. The noble gases are neither metallic nor non-metallic. They are inert in nature and do not undergo any reaction under standard laboratory conditions.

List of Non-Metals