Hybridized orbitals (can't understand diagram)

coconut62

Please see attachment.

1. "Now the 2s orbital and two of the 2p orbitals of B hybridize to form a set of three equivalent sp2 hybrid orbitals." The notes says.

Can someone tell me why are there two 2p orbitals in B? I thought electronic configuration of B is 1s2 2s2 2p1?

2. What does the [He] beside B mean?

Thanks in advance.

Attached Thumbnails

 

Borek

Orbitas - as a place for an electron - exist regardless of whether they are occupied or not.

It is a shortcut notation - replace [He] with configuration of the noble gas.

coconut62

Why is Helium needed? Is it the Boron itself hybridizes or it hybridizes together with He?

sjb-2812

Helium is not needed, the notation simply means the electronic configuration of He.

So, instead of 1s² 2s² 2p¹; as He is 1s² you can write it as [He] 2s² 2p¹. May not be so much of an advantage here, but in larger atoms like e.g. Gold, or Iodine having to write out lots of terms each time is prone to error.

Borek

Think about cesium. [Xe] 6s¹ looks much more neat than 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹, doesn't it? And they mean exactly the same.

coconut62

So the [He] is actually together with the dotted square, not the B on the left?

And is the energy level of the hybrid orbitals lower than the 2p's? And higher than the 2s?

Borek

You can put it that way.

coconut62

How about its energy level?

ycheff

B has three 2p orbitals. And one 2s.
Empty orbital doesn't hybridize.

coconut62

Where is its 1s?

ycheff

1s² - (or [He]) - closed shell.
It can't hybridize. Too much energy gap between 1s and 2s.

coconut62

So you're saying that a B atom never has a 1s subshell? Even when it is an independent atom and not bonded to others?

Borek

No, he says that 1s² exists, but doesn't matter when talking about hybrydization and can be safely ignored. But I agree that the original statement was lousy to say the least.

coconut62

How come boron has so many subshells when it has only five electrons?

1s2 2s2 2p1 no?

is the 1s2 empty?

Borek

Technically all possible subshells always exist, they are just not occupied in the unexcited atom.