The atom's stable configuration

[scientist91]

Hi,
I am new member of this forum, and I have one question for you. When the atom have 8 electrons in the last shell, why it have stable configuration? What makes the atom to be stable and what makes the atom to be reactive?
I know few things about this.
Generally speaking the CH2 molecule is very unstable. The carbon's configuration is:
1s^2 (means 2 electrons in the orbital), 2s^2, 2px^1, 2py^1, 2pz^0
So for methane to be produce one of the 2s electrons must go into the 2pz electron and the final configuration of carbon is:
1s^2, 2s^1, 2px^1, 2py^1, 2pz^1
so there are 4 bonds. But how that 2s electron went to the 2pz orbital. Where is the energy from?
Best regards.

 

[DrClaude]

Where is the energy from?

From the interaction with the other atoms.

Such models are very useful to understand chemical bonding, but they shouldn't be taken too far. One should not imagine that it starts with a carbon atom in the electronic configuration 1s² 2s² 2p², that the atom then gets excited to the configuration 1s² 2s¹ 2p³, and then it starts forming bonds with other atoms.