can any body send me notes of ch3 of class 10 science plzz
Answers
Science Chapter 3- Metals and non metals...
◼Metals: They are lustrous, opaque, ductile, malleable and also good conductors of heat and electricity. Most of the metals are solids at room temperature, except few like mercury. Zinc, copper, cobalt, calcium are some examples of metals.
◼Non metals: They do not possess the properties of metals. They are brittle and can be easily broken into sub-particles. They are bad conductors of heat and electricity and exists in both solids and gases except few. Hydrogen, carbon, nitrogen, phosphorus are some examples of non-metals.
◼Properties of Metals and Non- Metals:
- Melting and boiling points:
Metals have high melting and boiling points whereas non metals have low melting and boiling points
- Malleability and Ductility:
Metals are both malleable and ductile whereas non metals are neither malleable and ductile
- Density:
Metals generally have high density whereas, non metals' density is generally low.
- Luster:
Metals posses shining luster whereas, non metals do not have a luster
- Hardness:
Metals and usually hard whereas, non metals are generally brittle.
◼Chemical Properties of Metals:
- Metals react with air or oxygen to form metal oxide.
Example 2Cu + O₂ → 2CuO
- Oxides of metals can react with both acids and bases to produce salt and water. Such oxides are known as Amphoteric Oxides.
Example Al₂O₃ + 6HCl → 2AlCl₃ + H₂O
- Metals also react with water to form metal oxide. Metal oxide in turn can react with water to form metal hydroxide.
Example 2Na + 2H₂O → 2NaOH + H₂
- Metals also react with dilute acids to form salt and hydrogen. For example, magnesium reacts with dilute hydrochloric acid to form magnesium chloride and hydrogen.
Example Mg + 2HCl → MgCl2 + H2
◼Chemical Properties of Non-metals:
- Non-metals reacts with oxygen to form non-metal oxide.
Example C + O₂ → CO₂
- Non-metals do not react with water and acids to evolve hydrogen gas.
- Non-metals can react with salt solution; more reactive element will displace the less reactive non-metal.
Example 2NaBr(aq) + Cl₂(aq) → 2NaCl(aq) + Br₂(aq)
- Non-metals can also react with hydrogen to form hydrides.
Example H₂(g) + S(l) → H₂S(g)
◼Ionic Compounds: Compounds formed due to the transfer of electrons from a metal to a non-metal are known as Ionic Compounds.
◼Covalent Bond: The bond formed by sharing of electrons between the two atoms. They share their valence electrons to gain stability.
◼Steps of extraction of pure metals from its ores/steps for extraction of metals from its ore:
1️⃣ The enrichment of the ore.
2️⃣ The extraction of the metal.
3️⃣ The refining of the metal.
◼Corrosion: Metals when exposed to moist air for a long period of time, they become corroded. This is known as Corrosion. For Example, Silver reacts with moist air and becomes black in color due to silver sulphide coating and iron gets rusted and forms and reddish brown coating.
◼How to prevent corrosion?
Rusting can be prevented by oiling, galvanizing, painting, greasing etc.
To protect steel and iron from rusting, a thin layer of zinc are coated on them, this process is known as Galvanization.
◼Alloy: A mixture of two or more metals or metal and non-metal is known as an Alloy. Example: Brass, Bronze, solder etc.