All electrons in an atom are arranged in shells or energy levels around the nucleus of the atom. This arrangement is called ELECTRONIC CONFIGURATION. The shells or energy levels are usually represented as circles around the nucleus.

The closest shell to the nucleus is called K, the second is L, and the third is M etc.

N.B:

• The first shell is called the K-Shell and it can hold a maximum of only two electrons.
• The second shell is called the L-Shell and can hold a maximum of 8 electrons.
• The third shell is called the M-Shell ad can hold a maximum of 8 electrons also.

The electronic configuration(e.c) of some elements

Electronic configuration is the representation of electrons of atoms on shells by the dot and cross diagrams.

The electronic configuration of some elements;

• Carbon ( has six electrons hence number 6 on the periodic table )

E.C = 2:4

• Sodium ( has 11 electrons hence number 11 on the period table)

E.C=2:8:1

E.C=2:8:1