How can u detect the which d-orbital is used in making bond ? ?

This is much more simple than it sounds... 

s has 1 orbital; p = 3 orbitals; d= 5 orbitals; f= 7 orbitals. (you just need to memorize this) 
A maximum of 2 electrons can occupy each orbital. 

The number of orbitals that each atom has is based on the number of electrons it has and by consequence it's position on the periodic table. 

The orbitals occur in sequence. Whereby electrons fill first from the lowest energy level (1s) outwards to the highest. 
3p = the following sequence. 
1s, 2s, 2p, 3s, 3p: these 'sets' can hold the following electrons respectively (2+2+6+2+6) 18 which corresponds with argon on the periodic table. REMEMBER p has 3 orbitals, d has 5 orbitals. So, here there are 9 orbitals. 

The sequence through n=4 is: 

1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f 


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