(a) State any three differences between the physical properties of metals and non-metals.
(b) Differentiate between metals and non-metals on the basis of their chemical properties.
(c) State three reasons (of which at least one must be chemical) for believing that sodium is a metal.
(d) State three reasons (of which at least one must be chemical) for believing that sulphur is a non-metal.
(e) Which non-metal has been placed in the reactivity series of metals?
Answers
There are several differences between metals and non metals.
Explanation:
a) Three differences between metals and non metals based in their physical properties are :
- Metals are generally solid at room temperature and are lustrous while non metals can be solid, liquid or gases. ( exception sodium)
- Metals have high melting and boiling points while non metals generally have low melting and boiling points.
- Metals are good conductors of heat and electricity while non metals are generally poor conductors of heat and electricity. ( exception: graphite)
b) Differentiation between metals and non metals based on their chemical properties are:
- Metals are electro positive which means they lose electrons in chemical reactions while non metals are generally electro negative which means that they accept electrons in chemical reactions.
- The oxides of metals are basic in nature while the non metallic oxides are acidic in nature.
- Metals are good reducing agents while non metals are good oxidizing agents.
c) Three reasons why sodium is a metal are as follows:
- Sodium has a metallic lustre which is a property of metals. Although it is very soft at room temperatures.
- Sodium is placed in group one of periodic table along with other metals and the group is called as Alkali metals.
- Sodium is highly electro positive and readily loses it's one valence electron, which makes it highly reactive. ( chemical property)
d) Three reasons why sulphur is classified as a non metal are:
- It is poor conductor of heat and electricity like most of the non metals.
- Sulphur is insoluble in water but are soluble in organic solvents like benzene, toluene, etc. This is a property exhibited by non metals.
- The oxides of sulphur are sulphur dioxide and sulphur trioxide which when dissolved in water forms sulphuric acid. It follows the property of metallic oxides which are acidic in nature ( chemical property)
e) The non metal which is placed between the reactivity series of metals is Hydrogen.
- Hydrogen is placed in group 1 with Alkali metals which are highly electro positive metals like sodium, potassium, etc.
- The position of Hydrogen in modern periodic table is disputed but Hydrogen generally shows metallic characteristics, and hence is placed between the reactivity series of metals.
Explanation:
(a) Physical properties of metals and non-metals:
Metals:
- Metals have lustre.
- They are good conductors of heat and electricity.
- They are ductile and malleable.
Non-Metals:
- Non-metals do not have lustre.
- They are bad conductors of heat and electricity.
- They are non- ductile.
(b) Chemical properties of metals and non-metals:
Metals:
- They are hard in nature.
- They remain in solid state at room temperature.
- They form basic oxides.
- Hydrogen can be displaced from any acids or from water using metals.
Non-Metals:
- They are soft metals.
- They remain in solid and gaseous state at room temperature.
- They form acidic or neutral oxides.
- Hydrogens cannot be displaced from any kinds of acids or water.
(c) Sodium is obtained in solid state at room temperature. They have lustre and they can easily displace hydrogen from water. So these three properties confirm that sodium is a metal.
(d) Sulfur is mostly available in gaseous state at room temperature. Even they do not have lustre and they cannot displace hydrogen easily from water or acids.
(e) The non-metal hydrogen is kept as the reactivity sensor of elements.