Covalent Bonding - Single Bonds printable pdf download

Covalent Bonding - Single Bonds

C h e m g u i d e – q u e s t i o n s

COVALENT BONDING (single bonds)

You will need a copy of the Periodic Table for some questions.

1. A covalent bond consists of a pair of shared electrons between two atoms. How does this shared

pair hold the two atoms together?

2. Draw dots-and-crosses diagrams (showing outer electrons only) for the following covalent

compounds.

a) ammonia, NH

b) hydrogen sulphide, H

c) hydrogen iodide, HI

d) nitrogen trichloride, NCl

e) boron trifluoride, BF

The rest of the questions go beyond what you are likely to be asked for most UK-based syllabuses,

but you should try them anyway, even if your syllabus says that you don't need to know about

hybridisation. It isn't difficult, and will help your understanding of future topics.

If you go on using Chemguide you will find hybridisation discussed several times, particularly in

organic chemistry, because there is no other way of making sense of the structures of important

substances like ethene and benzene

In question 3, I want to guide you through the structure of methane, CH

, using a more modern view

of covalent bonding. Then in question 4, you will use the same process to explain the bonding in

some more complex molecules.

3. Carbon has the electronic structure 1s

. Thinking about the bonding in methane:

a) The first step is promotion of an electron to give 4 unpaired electrons. Show this happening, in

some combination of words and diagrams as you prefer.

b) The second step is hybridisation. Explain what this means, and what the result of it is.

c) The final step is the formation of molecular orbitals involving carbon's orbitals and four

hydrogen atoms. Describe what happens at this stage.

Covalent Bonding - Single Bonds