CaCl2 2 empty p orbitals?

[SaintJude]

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I'm reviewing VSPR theory, etc.

According to this university link, CaCl2 chloride has 2 empty p-orbitals. How can I figure that out just by looking at the Lewis structure?

 

[mcloaf]

Well, it has two sigma bonds and no lone pairs, so it's sp hybridized. It has three p-orbitals and one is tied up in the hybrid orbital, leaving the other two empty.

 

[SaintJude]

What? I missed this topic in Chem class, so I'm gonna need an explanation without an assumption of understanding. How do you know "it" (what is it?) has three p orbitals. One-sentence answers won't help me. Sorry.

 

[MedPR]

What? I missed this topic in Chem class, so I'm gonna need an explanation without an assumption of understanding. How do you know "it" (what is it?) has three p orbitals. One-sentence answers won't help me. Sorry.

"it" is the central atom, which is Ca.

If a central atom has two electron domains bound to it (an atom or lone pair of electrons is one electron domain), it is said to be sp hybridized. That is, bonding by 1 s orbital hybridized (mixed) with 1 p orbital. Since CaCl2 is only using 1 p orbital (hybridized with s to form two sp bonds, 1 to each Cl) it must have two empty/unhibridized p orbitals.

It's like if I give you four globs of paint, 1 yellow, and 3 blues. If I close my eyes and you show me a green glob of paint, I know that you still have 2 blue globs of paint left.

 

[chiddler]

Does that apply to everything?

Does BF3 have one empty P orbital because it's sp2 with no lone pairs?

 

[MedPR]

Does that apply to everything? I think so

Does BF3 have one empty P orbital because it's sp2 with no lone pairs?Yes. That's why BF3 is a lewis acid

🙂

 

[mcloaf]

What? I missed this topic in Chem class, so I'm gonna need an explanation without an assumption of understanding. How do you know "it" (what is it?) has three p orbitals. One-sentence answers won't help me. Sorry.

Sorry, I remember things better when I've distilled them thoroughly, which makes my explanations tend towards the terse. Thankfully we have MedPR around. 🙂

 

[chiddler]

🙂

so to draw the orbitals, it's only 3 SP2 orbitals right? and electrons occupy all of em.

 

[MedPR]

Sorry, I remember things better when I've distilled them thoroughly, which makes my explanations tend towards the terse. Thankfully we have MedPR around. 🙂

Ha, I read this a while ago and had no idea how to know Ca had two empty p orbitals. It wasn't until I read your answer that I realized what the concept was.

 

[mcloaf]

so to draw the orbitals, it's only 3 SP2 orbitals right? and electrons occupy all of em.

Where are those electrons and molecular orbitals coming from?

Calcium has two bonds, which means SP hybridization, not SP2. It only has two valence electrons, one of which will be in each of the bonds (the other electrons coming from the chlorines), leaving its remaining two P orbitals empty.

 

[chiddler]

Where are those electrons and molecular orbitals coming from?

Calcium has two bonds, which means SP hybridization, not SP2. It only has two valence electrons, one of which will be in each of the bonds (the other electrons coming from the chlorines), leaving its remaining two P orbitals empty.

talking about BF3, my friend

 

[mcloaf]

talking about BF3, my friend

😱

Sorry, I am dumb. And your explanation was spot on.

 

[MedPR]

so to draw the orbitals, it's only 3 SP2 orbitals right? and electrons occupy all of em.

For BF3? Yes. 1 sp2 orbital per bond. Also, if you're going to draw the orbitals, I think by convention you would also draw the empty p orbital on the B.

It's kind of like including the two dots for the lone pair on NH3. It's implied, but you draw it for simplicity/completeness.