[chimico]

Hello, to know how many and what atoms can be combine with another atom is important know the number electrons on the last orbital so if carbon can make 4 other bonds (because it need 4 electrons to complete the last orbital) why my book say we would expect that it can make 2 bonds and explain that putting one electron in a superior orbital and making like a mixed orbital?
This is only for carbon?
To atom make bond with other is compulsory that all electron must be in the same sublevel and not just in the same level?

Thanks!!

[DevaDevil]

I presume they mean SP-hybridization? the carbon mixes its available s and p-orbitals to form hybridized sp-orbitals for bonds.

CO₂ is a good example of sp hybridized carbon with 2 (double) bonds.

this is typical for, but not limited to carbon

[chimico]

Yes they mean the SP hybridation... but in chemical bonds must be considered only the electrons in the last sublevel not the electrons in all the level?
what happen in the last sublevel (p) for example there are 2 half ful orbitals and the last is empity after that the 2 half ful orbitals are filled?

thanks!

[thekid_frankie]

http://en.wikipedia.org/wiki/Orbital_hybridisation
Scroll down past the historical development and you'll see explanations for carbon's sp³ hybrid state and more.  What I gain from this is that in the excited state carbon's 2s and 2p sublevels are mixed (hybridized) to form four sp³ sublevels used for the four bonds in compounds such as methane (CH₄)

[chimico]

Why The valence bond theory would predict, based on the existence of two half-filled p-type orbitals, that C forms two covalent bonds?
The Carbon need 4 electrons to complete the last level so what is wrong?
Do the bond are formed ONLY in the more external half-filled orbitals ?

thank you