Page 2 - 3.Lesson Note-Elements,compounds and mixtures

Metalloids: These are the elements whose properties are intermediate between
metals and non-metals. They form a bridge between metals and non-metals

1. They are more brittle than metals.
2. They are usually less brittle than non-metallic solids.
3. They are usually semiconductors of electricity.
4. Some non-metals possess metallic lustre.
5. Example: Bismuth, Silicon, Germanium, Arsenic, Antimony
Compounds: Compounds are pure substances formed from two or more elements
chemically combined together in a definite proportion by mass.

Characteristics of compounds:

1. Two or more elements combine chemically to form a new compound.
2. The composition is fixed.
3. The new substance formed has totally different properties.
4. The constituents of a compound cannot be separated by physical means and
can be separated by chemical or electrochemical reactions.
5. They are pure and homogeneous.
6. They have fixed melting and boiling points.
7. They can be represented by a chemical formula.
8. Example common salt (NaCl), Sugar(C12H22O11), Water (H2O)