Covalent Bonding Practice Questions

Which substance does not contain covalent bonds?

• A ammonia
• B iodine
• C potassium bromide
• D methane

In a molecule of iodine, two iodine atoms are held together by a covalent bond.

Explain how this covalent bond is formed.

Draw a dot and cross diagram for a molecule of hydrogen, $\mathrm{H_2}$.

Draw a dot and cross diagram for a molecule of hydrogen chloride, $\mathrm{HCl}$.

Show only the outer shell electrons.

State the total number of electrons that are shared between the two atoms in a molecule of hydrogen chloride.

Draw a dot and cross diagram for a molecule of water, $\mathrm{H_2O}$.

Show only the outer shell electrons.

Carbon is in Group 4 of the periodic table.

Explain why a carbon atom forms four covalent bonds in a molecule of methane.

Draw a dot and cross diagram for a molecule of methane, $\mathrm{CH_4}$.

Show only the outer shell electrons.

Which is the typical order of magnitude of the diameter of an atom?

• A $10^{-6}\ \mathrm{m}$
• B $10^{-8}\ \mathrm{m}$
• C $10^{-10}\ \mathrm{m}$
• D $10^{-12}\ \mathrm{m}$

An oxygen molecule has a length of $0.000\,000\,000\,29\ \mathrm{m}$.

Write this length in standard form.

A hydrogen molecule has a diameter of $2.4 \times 10^{-10}\ \mathrm{m}$.

Calculate the number of hydrogen molecules that would fit, touching each other in a straight line, across a distance of $1\ \mathrm{cm}$.

Give your answer in standard form.

State the number of electrons that are shared between the two oxygen atoms in this molecule.

Oxygen is in Group 6 of the periodic table.

Explain why the two oxygen atoms in $\mathrm{O_2}$ are joined by a double bond.

Draw a dot and cross diagram for a molecule of carbon dioxide, $\mathrm{CO_2}$.

Show only the outer shell electrons.

Deduce the number of covalent bonds formed by a silicon atom and by a sulfur atom.

Use the group numbers to explain your answers.

Silicon forms a covalent compound with hydrogen only.

Deduce the formula of this compound.

Draw a dot and cross diagram for a molecule of carbon disulfide, $\mathrm{CS_2}$.

Show only the outer shell electrons.