Lithium

Atomic number : 3 Atomic mass : 6.941 g.mol-1 Electronegativity according to Pauling : 1.0 Density : 0.53 g.cm-3 at 20 °C Melting point : 180.5 °C Boiling point : 1342 °C Vanderwaals radius : 0.145 nm Ionic radius : 0.06 nm Isotopes : 2 Electronic shell : 1s2 2s1 or...

Helium

Atomic number : 2 Atomic mass : 4.00260 g.mol-1 Electronegativity according to Pauling : 2.1 Density : 0.178*10-3 g.cm-3 at 20 °C Melting point : - 272.2 (26 atm) °C Boiling point : - 268.9 °C Vanderwaals radius : 0.118 nm Ionic radius : unknown Isotopes : 2...

Types of Chromosomes

Chromosomes can be classified into four types depending on the position of the centromere in it. These are: 1. Metacentric Chromosomes  The chromosomes in which the centromere is in exactly middle position are called metacentric chromosomes. These chromosomes are V...

Number Of Chromosomes

Every plant and animal has fixed number of chromosomes. For example, the human beings have 46 chromosomes in every cell. The chromosomes of each species occur in pairs, out of which one comes from father and the other comes from mother. In this way, we can say that...