Symbols of certain elements are given. Write their electronic configuration and find the period and group in which they are included.

(a) 12/6C (b) 24/12Mg (c) 35/17Cl (d) 27/13Al (e) 20/10Ne

a) For carbon:

i. The atomic number of carbon = 6

ii. Hence, its electronic configuration will be = 2,4

iii. Carbon has 4 electrons in the outermost shell. Hence, it belongs to 4^th group number.

iv. In carbon (2,4), there are two shells. Hence, it belongs to second period.

For magnesium:

i. The atomic number of magnesium = 12

ii. Hence, its electronic configuration will be = 2,8,2

iii. Magnesium has 4 electrons in the outermost shell. Hence, it belongs to 4^th group number.

iv. In magnesium (2,8,2), there are three shells. Hence, it belongs to third period.

For chlorine:

i. The atomic number of chlorine = 17

ii. Hence, its electronic configuration will be = 2,8,7

iii. Chlorine has 7 electrons in the outermost shell. Hence, it belongs to 7^th group number.

iv. In chlorine (2,8,7), there are three shells. Hence, it belongs to third period.

For aluminium:

i. The atomic number of aluminium = 13

ii. Hence, its electronic configuration will be = 2,8,3

iii. Aluminium has 3 electrons in the outermost shell. Hence, it belongs to 3^rd group number.

iv. In aluminium (2,8,3), there are three shells. Hence, it belongs to third period.

For neon:

i. The atomic number of neon = 10

ii. Hence, its electronic configuration will be = 2,8

iii. Neon has 8 electrons in the outermost shell. Hence, it belongs to 8^th group number.

iv. In neon (2,8), there are two shells. Hence, it belongs to second period.