CBSE Class 10:Metals and Non Metals Part 1

Here are Important Notes and points for CBSE Class 10th science third chapter Metals and Non metals.

Physical Properties of Metals

1. Metals are Malleable, that is, they can be beaten into sheets
2. Metals are Ductile, they can be drawn into thin wires
3. Metals are good conductor of heat and electricity
4. Metals are lustrous and shiny, they can be polished
5. Metals are generally hard,(except for sodium and potassium which are soft metals)
6. Metals are solid at room temperature, except for Mercury
7. Metals have high melting point
8. Metals have high density
9. Metals are sonorous
10. Metals are usually silver and grey in colour except for gold and copper

Physical Properties of Non Metals

1. Non Metals are neither malleable nor ductile, i.c they are brittle
2. Non Metals are bad conductor of heat and electricity
3. Non Metals are generally soft, except for diamond
4. Non Metals are not lustrous and shiny, they dull
5. Metals are generally not strong, they can be broken
6. Non Metals can be solid liquid or gas at room temperature
7. Non Metals have generally low melting point and boiling point
8. Non Metals have Low density
9. Non Metals are not sonorous
10. Non Metals have many different colours

Exceptions in Physical properties of Metals and Non Metals

• All Non Metals are bad conductor of electricity but Graphite is very good conductor of electricity
• Iodine is non metal which has lustrous and shiny surface
• Alkali Metals like,lithium,potassium,sodium, are soft metals, which can be easily cut with knife. and Diamond is the hardest substance
• Mercury is liquid at room temperature, similarly Bromine is also liquid at room temperature
• Gallium and cesium have very low melting point, they can melt with the heat of our palm
• Diamond, has a very high melting point and boiling point

Chemical properties of Metals
All metals are electropositive, i.e they have free electrons due to which form cation, this very reason makes them good conductor of electricity 

Important Valencies of Metals
1.Lithim,sodium potassium have 1 free electron to donate
2.Calcium,Zinc,Magnesium,Iron,Copper Lead, Barium ,Nickel,Mercury have 2 Free electrons to donate
3.Aluminium, Iron, Copper have 3 free electrons to donate

Reaction of Metals with Oxygen

All Metals react with Oxygen to form Metal Oxides.Metal Oxides are generally Basic in nature.but there is exception in the case of Aluminium and Zinc, which form amphoteric oxides as they show both acidic and basic behavior

Sodium and Potassium React vigorously with oxygen and catch fire, as they are highly reactive.for this reason, They are stored in Kerosene.

Most Metal oxides are insoluble in water, but some Metal oxides dissolve in water to form alkalis
for e.g
Sodium reacts with oxygen to form Sodium oxide 

4N + 20₂ --------------->N₂O
When sodium oxide is dissolved in water it forms Sodium Hydroxide
N₂O + H₂0 -------------------->2Na0H

Magnesium,Aluminum and Zinc do not burn at room temperature but form a layer of metal oxide, however they burn in air to form metal oxide when heat energy is provided, this shows that they are less reactive than sodium and potassium Iron and copper do not burn even at strong heating, however iron fillings burn vigorously when sprinkled in fire.

Reaction of Metals with Water
When metals react with water (hot or cold) Metal hydroxides are form and when Metals react with Steam then Metal Oxides are form

1. Metals which react with water and form Metal Hydroxides
   
   • When potassium reacts with cold water hydrogen gas is released, and it being exothermic reaction, lot of heat energy is also released due to which hydrogen catches fire.In this reaction product formed is potassium hydroxide
   • Sodium reacts similarly with Cold water to form sodium hydroxide, and in this case also hydrogen catches fire
   • When calcium reacts with Cold water, heat energy is not strong enough for hydrogen to catch fire, but pieces of calcium start floating in water, due bubbles of hydrogen stick to the surface of Calcium
   • Magnesium reacts with hot water, and it too starts floating like calcium due the bubbles of hydrogen gas sticking to its surface
2. Metals which react with Steam and form Metal Oxides
   
   • Metals like Aluminum, zinc and iron do not react with cold or hot water
   • They all react with steam to form their respective oxides and hydrogen gas>
3. Metals like Gold,Lead,Copper , and Silver do not react with water at all

Reaction of Metals with Acids

1. When Metals react with acid, hydrogen gas is released and Metal salt is formed
2. Metals like Copper or silver which are lower in reactivity series than hydrogen do not displace hydrogen from dilute acids
3. When Metals react with Nitric Acid, hydrogen gas is not released this is due the fact that Nitric acid is very strong oxidising agent, so it oxidises hydrogen to water
4. Very Dilute Nitric Acid reacts with Magnesium and Manganese to release hydrogen gas

Aqua Regia
Aqua regia is freshly prepared mixture of 1 part of concentrated acid and 3 parts of concentrated hydrochloric acid.Aqua regia is highly corrosive and fuming liquid, it can dissolve all metals.Aqua regia can even dissolve gold and platinum The Reactivity series of Metals The arrangement of metals in vertical column in the order of decreasing reactivities is called reactivity series of metals
 Mnemonic device to learn Reactivity series of metals In Hindi:
Kedar(k) Nath(Na) Ka(Ca) Mali(Mg) Allu(Al) Zara(Zn) Fike(Fe) Pakata(Pb) hai(H) Kyuki(Cu) Hg Ag Au

Displacement Reaction
Metals which are more reactive displaces less reactive metal from their salt solution For e.g Iron is more reactive than copper sulphate, and if iron fillings are put in copper sulphate solution it displaces copper to form Ferrous Sulphate. However, if copper was to be put in zinc sulphate solution, nothing will happen as it is less reactive than Zinc.

Reaction of Metals with Hydrogen
Metals generally do not react with Hydrogen as both form compounds by losing electrons, so hydrogen does not accept electron given by metal, however highly reactive metals like sodium, potassium can force hydrogen to accept electrons and form Metal hydrides

Chemical Properties of Non Metals
Non Metals are electronegative in nature, i.e they attain noble gas configuration by gaining electrons and forming Anion.

Reaction of Non Metals with Oxygen
Non Metals react with oxygen to form non metal oxides.These non metal oxides are Acidic in nature. A solution of non metal oxides will turn blue litmus paper red There are some non metal oxides which are neutral in nature for example, carbon monixide, Water, Nitrogen monoxide,Dinitrogen monoxide etc.

Reaction of Non Metals with Water
Non metals do not react with water at all, therefore highly reactive non metals like sulphur and phosphorous are stored in water

Reaction of Non Metals with Acid
Non Metals do not react with Dilute acids, in another words, hydrogen gas is not displaced by non metals  

Reaction of Metals and Non Metals

Cation:It is a positively charged ion.Metals form cation by the loss of one or more electrons, only the hydrogen ion and ammonium ion are the cations formed by non metals

for e.g Na - e^- ------> Na⁺

Anion:It is a negatively charged ion.Non Metals form anion by the gain of one or more electrons.

for e.g Cl + e^- -------------->Cl^-

Ionic Bond
 The ionic bond formed by the transfer of electrons from one atom to another is known as an ionic bond. When a metal reacts with non-metal transfer of electrons take place from metal atoms to the non metal atoms , and ionic bond is formed.

Formation of ionic bond

When sodium reacts with chlorine, it transfers its 1 outermost electron to the chlorine atom. By losing 1 electron sodium atom forms a sodium ion, and by gaining 1 electron chlorine forms chlorine ion. Sodium ion has positive charge and chlorine has negative charge, and due to their opposite charges they are held together by electrostatic force to form sodium chloride
 Properties of Ionic Compounds

1.Ionic Compounds are usually solids because their oppositely charged ions attract one anothe strongly and form a regular crystal structure.The crystals of ionic bonds are however brittle

2.Ionic compounds have high melting and boiling points. for example sodium chloride has melting point of 800⁰ celcius. As these compounds are made up of positive and negative ions.There is strong force of attraction between the opposite charged ions, and in order to break this force of attraction , alot of heat energy is required
3.Ionic compounds are usually soluble in water but insoluble in organic solvents like ether, acetone,alcohol,benzene,kerosene.The ionic compounds dissolve in water because water has high dielectric constant due to which it weakens the attraction between the ions. 4.Ionic compounds conduct electricity when dissolved in water or when melted, however they do not conduct electricity in solid state, this is due to the fact that in solid state ions are held together in fixed positions.In molten or dissolved state the ions are free to move and hence conduct electricity