Question

The electronic configuration of the three elements A, B, C are as follows
A:2,8
B:2,8,7
C:2,4

a) which of these elements are metal and non metals?
b) which of these two combine to form an ionic bond and covalent bond?
c) identify elements A and C? ​

Answer 1

A is noble gas neon

B is non metal chlorine

C is non metal oxygen

Answer 2

A=1s2, 2s2, 2p6
It has 8 electrons in the valance shell it means it is the member of group 8th of the periodic table and also its valence shell is complete that's why it is noble gas and its name is NEON.neon is a non-metal(all the elements to the right side of the periodic table are non-metals).

B=1s2, 2s2, 2p6, 3s2, 3p5
Its valence shell contains 7 electrons that's why it is the member of group 7th. its atomic number is 17 it means it is chlorine and chlorine is also a non-metal.

C=1s2, 2s2 3s2
It has 4 electrons in the valance shell it is the member of group 4th. its atomic number is 6 it means it is carbon and we know that carbon is a non-metal

The nature of bond depends on the atomic size and nuclear charge.
Greater the nuclear charge, smaller will be the atomic size and the bond formed by the element will be covalent bond.