1 . Physical properties of metals and non - metal
i) Discuss some Physical properties of metals and non - metal with example and diagram .
2 . Chemical properties of metals and non - metals
i) Discuss some Chemical properties of metals and non - metal with example and diagram
Class 8 .
Science .
Chapter 4 - Metals and non-metals
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Answers
Answer:-
1.
Physical properties of Metals:-
- Sonority :- Metals generally produce sound when they touch other objects.
- Most of the metals exist in the solid state. [ Exceptional case - Mercury (Hg) is a liquid metal at room temperature ].
- Lustre :- Metals are lustrous (they shine when light is reflected on them).
- Malleability:- Metals can beaten into thin sheets.
- Ductility:- They can be used to make thin wires.
- Metals are generally hard in nature. [ Exceptional case - Sodium(Na) and Potassium (K) are soft metals. ]
- They are good conductors of heat and electricity.
- They have high melting and boiling points.
Physical properties of Non Metals:-
- They are non malleable and non ductile.
- They can be solids or liquids or gases at room temperature.
- They are non sonorous and non lustrous.
- They are poor conductors of heat and electricity.
- They have low melting and boiling points.
- Non metals are brittle(breakable) in nature.
2.
Chemical properties of metals:-
- Metals are electro positive in nature.
- They have low electro negativity.
- Most of the metals are alkaline(form basic oxides) in nature.
- They have smaller ionic radius.
- Metals are ready to lose their electrons to get stability (non reactive).
- They have high density
Chemical properties of Non Metals:-
- Metals are electro negative in nature.
- They have high electronegativity.
- Most of the non metals are acidic in nature.
- They have larger ionic radius when compared with metals.
- They are ready to gain the electrons to get stability.
- They have low density.
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Chemical properties of metals and non metals:-
- Losing of Electrons:- Metals generally lose electrons to get the nearest stable element configuration (Noble gas configuration). so, they lose electrons.
Example:- Calcium (Ca) loses two electrons to get stability.
- Electro - positivity:- In an atom of an element ; the number of protons are equal to the number of electrons. When metals lose electrons , the number of electrons will be less when compared to number of protons. Protons are positive sub - atomic particles. As , number of protons are more ; the element is said to be Electro positive which is a metal.
Example:- Na (atomic number - 10) lose an electron to get Neon's (Noble gas) configuration or to form Sodium Ion (Na⁺). So, it is a metal.
- Electro - negativity:- Here too, If non metals gain electrons, The number of electrons will be increased in the atom of that element. As there are more number of electrons, the element is said to be Electro - Negative.
Example:- Chlorine (Cl) gains an electron to get Argon's configuration or forms Chloride ion (Cl⁻). so , It is a non metal.
- Atomic radius:- A metal is electro positive. That means , It has more number of protons. Protons are located in the nucleus of an atom. Ionic radius is the distance between the centre of the nucleus and the outermost orbit of that Ion. If protons are more, they decrease the atomic radius by occupying the space in the nucleus. So, Metals have smaller ionic radius.
Non Metals have high electro - negativity, that means number of protons are less than the number of electrons. so, they occupy less space. So, Non Metals have larger ionic radius when compared with metals.
- Density:- Density depends on the mass of an object. In case of metals , they have greater atomic masses when compared with non metals. So, Metals have high density when compared with non metals.
★Concept :-
A material can be classified as metal or non-metal based on there properties.
- Though physical properties are quite reliable, Chemical properties are better indicators to determine the metallic and non-metallic nature of a given material.
- Metals like sodium and potassium are soft and can be cut with a knife.
- Mercury and Gallium are the metals which are found in liquid state at room temperature.
- Generally, Metals are hard to touch and in exist solid state.
★ Physical properties of metals and non - metal with examples:
★ Metals :-
Conductivity - Metals (such as iron or copper) are good conductors of heat and electricity.
Ductility - Metals (such as aluminium and copper) are ductile, which means that they can be drawn into wires.
Hardness - All metals are hard though there are some exceptions. Sodium and potassium are soft and can be cut with a knife.
Lustre - Metals (such as gold, silver and copper)are lustrous, which means that they reflect light from their surface and can be polished.
Malleability - Metals (such as silver and aluminium) are malleable, which means that they can be beaten into thin sheets.
Physical State - Most metals remain solid at room temperature, except mercury and gallium which remain liquid at room temperature.
Sonorous - Metals produce ringing sounds when they are struck and hence, they are sonorous, except Mercury which is liquid in nature.
Examples - Iron, copper, aluminium, calcium, magnesium, etc.
★ Non-Metals :-
Conductivity - Non-metals (such as coal or sulphur) are poor conductors of heat and electricity. Graphite is an exception as it is a good conductor of electricity.
Ductility - Non-metals are brittle (break down when struck) and hence, they cannot be drawn into wires.
Hardness - Most non-metals are soft. Diamonds are exceptions as they are the hardest material found on Earth. However, they are also very brittle and break when struck with a hammer.
Lustre - Non-metals (such as coal) are generally dull and do not reflect light. Hence, they lack metallic lustre.
Malleability - Since non-metals break easily, they cannot be pounded into sheets.
Physical state - Most non-metals exist in two of the three states of matter at room temperature: Gases (such as oxygen), and Solids (such as carbon).
Sonorous - Non-metals are non-sonorous and do not produce the typical metallic sound when they are struck
Examples - Sulphur, carbon, oxygen, phosphorus, etc.
★ Chemical properties of metals and non - metal with examples:
- Non-metals react with oxygen to give oxides which are acidic in nature.
- Metals react with oxygen to give oxides that are basic in nature.
- Thus, Metal oxides are basic in nature and Non-metal oxides are acidic in nature.
- Non - Metals usually do not react with acids.
- Metals easily get corroded. The detoriation or tarnishing of a metal when it reacts with the components of air is called Corrosion.
- Corrosion of iron is called rusting.
- Thus, Different metals react with the components of air in different manner at different rates and conditions.
Example :-
Aim: To know the reaction of oxygen with metals and non-metals.
Materials required: A metal sample -magnesium and a non-metal sample -sulphur, spiritlampor Bunsen burner and litmus papers, etc.
Procedure:
- Take a small strip of magnesium and note its appearance. Burn it. Note the appearance after burning.
- Collect the ash of magnesium in a test tube and add some distilled water to it.
- Test the solution withred and blue litmus papers. Note the colour change.
We observe that, The red litmus paper turns blue when it is dipped in the solution of water and Magnesium ash indicating the solution is basic in nature.
Conclusion :- More reactive metal can replace a less reactive metal, but a less reactive metal cannot replace a more reactive metal