Author Question: How many valence electrons are there in an atom with 24 electrons? (Read 693 times)

tth · **on:** Sep 20, 2013

Considering I was not given the element name, this is all the information I have to figure out the valence electron number.

Can someone please show me the steps and how to arrive at the correct answer please!

folubunmi · **Reply #1 on:** Sep 20, 2013

First ring takes 2 electrons
next one takes 8
next one takes 8 again
last ring has 6 electrons left
6 valence electrons

Sandstorm · **Reply #2 on:** Sep 20, 2013

for a neutral atom with 24 electrons, the element is Cr, this is a transition metal. it has 2 valance electrons, those of the 4s orbital. hybridization of Cr allows for its other oxidation states.

futuristic · **Reply #3 on:** Sep 20, 2013

Atoms do not have a charge so, knowing that the atom has 24 electrons tells us the atom is the one having an atomic mass of 24 - its chromium. Chromium has 1 valence electron; its electron configuration is: 1s2 2s2 2p6 3s2 3p6 4s1 3d5. We would expect the final electron configuration to be 4s2 3d4, but because of the greater stability of having a half-full d sublevel, one 4s electron moves to the 3d giving (instead of 4s2 3d4) 4s1 3d5. Valence electrons are those with the highest principle quantum number - 4th energy level in this case.