How many valence electrons does molybdenum have? (give only 1 answer)

Question

Go to this site and look for the electrons available in the outside shells. Click on element #42 and scroll down the menu on the left side until you come to electron configuration. http://www.webelements.com/

so is it 1

No. The answer can range from 2 to six. In multivalent atoms, it can have several available valence electrons.

I know that the oxidation state (valence) of Mo is almost NEVER 1. The term "valence electrons" or "valence shell electrons" or "outer shell electrons" has a number of meanings. I don't know which your instructor is using. However, the term valence electrons usually is synonymous with "outer shell electrons." The problem here, is that the simpler elements, such as oxygen, fluorine, etc have outer shells and outer shell electrons that DON'T involve any of the inner (either partially or completely filled) shells so there is no ambiguity in knowing which electrons are under discussion. When we come to Sc (element #21), however, we start filling the inner 3d orbitals. Sc has a configuration of [Ar]3d1 4s2. Some will tell you that Sc has two electrons in its outer shell and others will tell you that Sc has three valence electrons. Both are right if we understand what we are discussing. If we define valence electrons as those that were not present in the preceding noble gas, ignoring FILLED sets of d or f orbitals, (essentially we are saying the number of electrons available for bonding) then I would venture that Mo has six valence electrons. The electron configuration is [Kr]4d⁵ 5s¹ It is true that Mo has other valance states from -2 to +6, but it has six electrons AVAILABLE for bonding and there are many compounds in which Mo has an oxidation state of +6. This is really a tough question to answer because of the ambiguity involved. I hope I have given you sufficient information to know how to answer the question for yourself.

Answer 1

The answer is 6.