Question

a) Define non-metals. Give five examples of non-metals.
b) Name a non-metal which conducts electricity.
c) Name a non-metal having lustre (shining surface)
d) Name a non metal which is extremely hard
e) How do non-metals react with oxygen? Explain with an example. Give the equation of the reaction involved. What is the nature of the product? How will you demonstrate It?

Answer 1

Non metals are elements which lack metallic properties and hence identifies as non metals. If an element does not look metallic, cannot be transformed into a thin wire, unchangeable shape or structure, which doesn’t conduct heat and electricity, and doesn’t have a higher melting or boiling point than that element is said to be a non metal. All the non metals are placed under p-block elements belonging to the group 13, 14, 15,16,17,18. Characteristics of nonmetals are brittle, non lustrous, low melting point, low boiling point, etc.

Complete step by step solution:
A periodic table is a table where all the elements are placed in blocks such as s-block, d-block, p-block, f-block depending on its physical properties, chemical properties, characteristics etc. The elements which lack metallic properties are known as Non metals.
Non metals are simply defined as the element that doesn’t showcase the metallic properties. They are placed mainly in p-block on the right hand side of the periodic table. $Hydrogen(H)$ is an exception, it’s a non metal which at room temperature and pressure which is placed on the upper left corner of the periodic table (s-block) One of the elements is placed in group 1 .i.e. $Hydrogen(H)$ others in group 14.i.e. $Carbon(C)$ , in group 15 there are two non metals .i.e. $Nitrogen(N)$ & $Phosphorus(P)$ , In group 16 there are three elements .i.e. $Oxygen(O)$ , $Sulphur(S)$ & $Selenium(Si)$ , most of group 17 $Fluorine(F),\;Chlorine(C),\;Bromine(Br)\;and\;Iodine(I)$ And all the elements from group 18 are non metals. Metals are separated by non metals by a line which diagonally cuts through the periodic table having elements with partially filled p orbitals.
As we know one of the characteristics of non metal is that they do not conduct heat and electricity, But $Graphite$ , a non metal which is an exception that conducts electricity. Graphite is a form of carbon and as carbon is non metal with a good conductor of electricity which indirectly makes graphite a good conductor of electricity. In a graphite molecule, one valence electron of each carbon atom remains free, thus making graphite a good conductor of electricity.
A non metal having a lustrous property (Shining surface) of a metal is $IODINE$ & $Diamond$ .
Carbon (non metal) exists in various forms. These forms are known as allotrope. $Diamond$ is an allotrope which is the hardest non metal with high melting and boiling point.
A non metal reacts with oxygen and forms acidic oxides and neutral oxides. These oxides are covalent in nature as it is formed by sharing the electrons. When carbon burns in the presence of air .i.e. Oxygen forms Carbon dioxide which is acidic in nature.
For example, carbon reacting with oxygen
$C{}_{(s)} + O{}_2 \to CO{}_{2(g)}$
Acidic product is formed. It can be demonstrated by dissolving CO2 in water to form a product called carbonic acid. This product when added to a blue litmus solution, it changes the solution to red colour confirming that the product is acidic in nature.

Note:
Non metals are the elements lacking metallic properties belonging mainly to the p-block of the periodic table, Hydrogen being an exception as it’s placed in the s-block. The basic properties of non metals are brittle, non-lustrous, low melting and boiling point,etc.