[Watermelon]

I can understand that HCl (Hydrogen Chloride) is H-Cl, I can understand that CO² is O=C=O.

Then my homework suddenly throws this at me:

"Draw a structural formula of CH²F² (Difluoromethane)."

... I've just learnt about the entire concept of structural diagrams, could you NOT do that to me? ಠ_ಠ

Anyways, I'm not sure how to do this, could anyone help me please?

Edit: Wikipedia shows me this: (sorry if it's a bit large)



Looking at this, I can get that each atom shares one electron with carbon so everyone has a full outer shell.

.. but I don't understand why one of the lines are thick, or why one of them is 'striped'.

[UG]

This structure is meant to illustrate the 3 dimensional shape of the molecule. The thick triangle shaped line indicates a bond coming out of the plane of the page, and the dashed wedge indicates a bond going into the plane of the page. The other two bonds are in the same plane as the page. Difluoromethane has an approximately tetrahedral shape (if all the bonds were to the same atom, the shape would be tetrahedral) and the diagram shows this. I am sure you can also draw it without showing the geometry (unless specifically specified) like so:

[Watermelon]

Ah okay, thankyou. Now I have to do C²H⁶ (ethane)

I'm beginning to wonder if drawing structural diagrams is more of a trial-and-error thing rather than logic.

[Watermelon]

Guys, are lone pairs always necessary to put into a structural diagram?

[sjb]

Guys, are lone pairs always necessary to put into a structural diagram?

Not necessarily always, in my experience. Most of the time they are added, it is to draw attention to them in some way.

[juanrga]

Ah okay, thankyou. Now I have to do C²H⁶ (ethane)

I'm beginning to wonder if drawing structural diagrams is more of a trial-and-error thing rather than logic.

It is logic plus some experience

• .

For instance H only has one valence electron, therefore cannot be in the middle of two atoms (not C-H-C). That is, H only can be at ends as in your above CH₂F₂.

C has valence 4 and can bond to a H or to another C. Therefore, you can deduce a (C-C) bond. Now adds Hydrogen atoms up to complete the valence 4 for the C...

• When you got some experience, you can write many structures without thinking almost automatically.