Properties Of Metals G Ludhiana

PRESENTED BY: Mr. BALJINDER SINGH SCIENCE MASTER GOVT. GIRLS SEN. SEC. SCHOOL, HARGOBINDPUR (LDH.)

PROPERTIES OF METALS At present about 115 elements are known which have numerous properties and form millions of compounds. All the elements are mainly divided into three groups.

Metals Non metals Metalloids This division was firstly done according to their physical appearance. Some elements have shining surface others don’t have. Some examples of metals are iron, potassium, aluminium, gold, copper, tin, lead etc.

PHYSICAL PROPERTIES 1. Physical state: Most metals are solid at room temperature but some exceptions are there. For example mercury (Hg) is liquid at room temperature. Examples of solid metal are gold (Au), potassium(K), iron (Fe) etc.

2. Melting point and boiling point: Melting and boiling points of metals depend upon the strength of bonds present in the molecules of metals. Metals with week bonds have low melting and boiling points where as metals having strong bonds have high melting and boiling points.

3. Lustre: Metals have lustrous surface. This is due to the presence of free electrons in the atoms of metals. These free electrons absorb energy and jump to the higher orbits. When these return, electrons radiates energy and this gives metals lustre.

4. Ductility and malleability: Metals are ductile i.e. these can be hammered into thin sheets. Gold is the most ductile metal. Metals are also

malleable i.e. these can be drawn into thin wires for example copper is used to make electrical wires.

5. Conductance: Metals are good conductors of heat and electricity. This is due to the presence of free electrons in the outer most shell of atoms. Silver is the best conductor of electricity.

6. Hardness: Most metals are hard but sodium (Na) and potassium (K) are soft and these can be cut with a knife.

7.Density: Generally most metals are having high density due to strong bonding between the atoms of the metals.

CHEMICAL PROPERTIES 1. High reactivity: Metals are highly reactive due to less ionization energy and bigger size of atoms. The most reactive metal is francium (Fr).

2. Reaction with oxygen: Metals react with oxygen to form basic oxides which convert red litmus to blue litmus for example 4Na

+

Sodium

O2

2Na2O

oxygen

sodium oxide

When these oxides are mixed with water these form bases. Na2O

+

Sodium Oxide

H2O

2NaOH

water

sodium hydroxide

3. Electropositive nature: Metals are electropositive in nature because these form positively charged ions by losing valence electrons. Na Mg

Na+ + Mg2+ +

e2e-

4. Reaction with Hydrogen: Some metals react with Hydrogen to form metal hydrides. Example:2 Na

+

H2

2NaH

5. Reaction with acids: Metals react with acids to produce hydrogen gas. Example:Zn

+

2HCl

ZnCl2 + H2

Mg

+

2HCl

MgCl2 + H2

BIBLIOGRAPHY

TEXT BOOK OF 10+1 KALYANI PUBLISHERS