Is Matter Around us Pure Notes

• In metals the atoms are very closely packed together and have special type of bonds known as metallic bonds. Because of close packing of atoms metals are quite hard.

Properties of Metals:

1. Metals are solids at room temperature.

Exception: mercury is liquid at room temperature. Gallium and Cesium become liquid at a temperature slightly above room temperature (303 K)

2. Metals are hard.

Exception: Sodium and potassium are soft metals.

• A non-metal is an element that is neither malleable nor ductile, and does not conduct electricity.

Properties of Non-Metals:

1.  Non-metals are either gases or solids at room temperature.

Exception: Bromine is liquid at room temperature

2. Non-metals are neither malleable nor ductile in nature.
3. Non-metals are poor conductors of electricity.

Exception: Graphite is a good conductor of electricity. It is an allotrope of carbon.

• A compound is a substance made up of two or more elements chemically combined in a fixed proportion by mass.

For example water (H₂O) is a compound made up of two elements, hydrogen and oxygen.

Hydrogen and oxygen are present in the ratio of 2: 16 or 1: 8 by mass. In pure form of water form any source the two elements are present in same fixed ratio i.e. 1 : 8 by mass.

Types of Compounds:

• The compounds are classified into two types based on the source of origin. These are:
• Inorganic compounds
• Organic compounds