Why the valency of copper does not match with its atomic number?
Answers
Basically, there are 18 because each shell is divided into s, p and d sub-shells. s always holds 2, p always holds 6 and d always holds 10 (there's an f shell that holds 14, it goes up in 4's xD)
Basically, shell 3, when full, looks like this:
1s2, 2s2, 2p6, 3s2, 3p6, 3d10
There are 2 on the 1st shell, 2+6=8 on the 2nd shell, and 2+6+10=18 on the 3rd shell
I can follow your electron configuration for shell 3.
But the reason they only tell us 8 of the electrons occupying the 3rd shell and not 18 is still not clear. (This assumes that they have left out the 10 electrons in the 3d orbital.) For Simplicity? Well, I hope there is a more profound reason.
Can't believe I always used to write e.g electron configuration of calcium 2,8,8,2. After looking closely it actually relates to the electron config. shown at AS e.g 1s2, 2s2, 2p6, 3s2, 3p6 4s2. The 2 stands for the 1s2. The 8 stands for the 2s2 and 2p6. And the third 8 stands for 3s2 and 3p6. And lastly the 2 standing for 4s2.
Answer:
Copper has an atomic number of 29 and its electronic configuration is 1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s1. According to Aufbau Principle, 4s orbital is filled before 3d orbital and hence, the last electron (in case of copper) fills the 3d orbital. This gives the copper atom a choice to lose either 1 electron from 4s orbital to achieve fully filled 3d orbital or lose 1 electron each from 4s and 3d orbitals. In first scenario, we end up with cuperous or Cu(I) and in the second case, we have Cu(II), that is, +2 valency.
HOPE IT HELPS YOU.
mark it as brainliest.