Asymmetric Carbon: Why Treat - Sign as Group?

[gracy]

My teacher says in picture (1) carbon atom is Asymmetric carbon atom. I don't know why. I know asymmetric carbon atom are those carbon atoms which are bonded with four different groups/atoms by single bonds. But why would we treat a negative sign as a group or atom?
And I also want to ask for whatever reason we are treating negative sign as a different group we must treat + sign in a same way. Hence, carbon atom in (2) should also be asymmetrical. Right?

 

[copper-head]

Hi Gracy,
It would help if you would let us know what level class this is for. The explanation level should greatly depend on that.

 

[Borek]

Hint: difference in charges means difference in the number of electrons present. They have to "be somewhere".

 

[gracy]

They have to "be somewhere".

You mean negative charge isn't present there alone there must be an atom carrying that negative charge?

 

[Borek]

No. There is no atom carrying the charge.

The electron ha to be somewhere. For example in a water molecule, in an ammonia molecule, there are electrons that are not accompanied by an atom (it happens that these molecules don't carry a charge, but the idea is exactly the same).

Where do these electrons reside?

 

[Ygggdrasil]

Are these examples you made up or your teacher made up? I don't think these represent any actual molecules that would exist (for example, the nitrogen with only a single chemical bond would be very unstable).

In general, however, it may be useful to consider the geometry of the carbon (i.e. is it trigonal planal, trigonal pyrimidal, tetrahedral, bent, linear, etc).

 

[gracy]

Are these examples you made up or your teacher made up?

My teacher.

 

[gracy]

The electron ha to be somewhere. For example in a water molecule, in an ammonia molecule,

I think there are partial charges in water and ammonia molecules.

 

[Borek]

I think there are partial charges in water and ammonia molecules.

We are not talking about dipoles here.

Have you ever heard about a lone pair? An orbital?