Metals and Non Metals
NCERT Class 10 • Science • Chapter "Metals and Non metals" | NCERT Class 8 • Science • Chapter "Materials Metals and Non Metals"
Metals and Non Metals
Elements are broadly divided into metals and non metals on the basis of their physical and chemical properties. A few elements show properties of both and are called metalloids, while a handful of well known exceptions must be remembered separately.
Properties and Exceptions
- Metals are lustrous, malleable, ductile, sonorous and good conductors of heat and electricity.
- Malleability is the ability to be beaten into sheets and ductility the ability to be drawn into wires.
- Non metals are generally dull, brittle, and poor conductors of heat and electricity.
- Mercury is the only metal that is liquid at room temperature; bromine is the only liquid non metal.
- Sodium and potassium are so soft they can be cut with a knife, unlike most metals.
- Graphite, a form of carbon, conducts electricity even though carbon is a non metal.
- Iodine is a non metal that is lustrous, and diamond is the hardest known natural substance.
Reactivity Series and Alloys
- The reactivity series arranges metals in decreasing order of their tendency to lose electrons and react.
- Potassium, sodium, calcium and magnesium lie high in the series while copper, silver and gold lie low.
- A more reactive metal displaces a less reactive one from its salt solution, which is a displacement reaction.
- Highly reactive metals are extracted by electrolysis, moderately reactive by reduction with carbon, and low reactivity metals occur free in nature.
- Metals react with oxygen to give basic oxides and non metals give acidic oxides.
- An alloy is a homogeneous mixture of a metal with another metal or a non metal, made to improve strength, hardness or resistance to corrosion.
- Steel, stainless steel, brass, bronze and solder are important alloys.
- Amalgam is any alloy in which one of the metals is mercury.
- Non metals such as oxygen, nitrogen, sulphur and phosphorus are essential to life and to industry alike.
| Property | Metals | Non Metals |
|---|---|---|
| Lustre | Lustrous | Dull, except iodine |
| Malleability | Malleable and ductile | Brittle |
| Conduction | Good conductors | Poor, except graphite |
| Oxide nature | Basic | Acidic |
Alloy — a homogeneous mixture of a metal with another metal or non metal, made to improve its properties.
Hindi me samjhein
पारा एकमात्र द्रव धातु है और ब्रोमीन एकमात्र द्रव अधातु। ग्रेफाइट अधातु होकर भी विद्युत चालन करता है, और आयोडीन अधातु होकर भी चमकीला है। ये अपवाद परीक्षा में बार-बार पूछे जाते हैं।
Exam me kaise aata hai
- The only liquid metal at room temperature is — mercury
- The only liquid non metal is — bromine
- Which non metal conducts electricity — graphite
- Metal oxides are generally — basic
UPSC/State PSC ke liye
- The method of extraction follows the reactivity series: highly reactive metals need electrolysis because carbon cannot reduce their oxides.
- Alloying changes properties because the different sized atoms disturb the regular lattice, which makes the metal harder and less easily deformed.
Yahan confuse hote hain
✗ All metals are solid at room temperature | Mercury is liquid at room temperature | ✓
✗ No non metal conducts electricity | Graphite conducts electricity | ✓
✗ Non metal oxides are basic | Non metal oxides are acidic | ✓
Ek nazar me
- Metals are lustrous, malleable, ductile and good conductors; non metals usually are not.
- Mercury, bromine, graphite and iodine are the standard exceptions.
- Reactivity series decides displacement reactions and method of extraction.
- Alloys improve strength, hardness and resistance to corrosion.