IGCSE Bonding (Double Science)

Covalent bonding occurs between...

• metals

• non-metals

• metals and non-metals

Ionic bonding usually occurs between...

• Metals

• Non-metals

• Metal and non-metal

What type of bond connects the hydrogen and the oxygen together in H₂O?

• Ionic bonds

• Covalent bonds

• Intermolecular bonds

• Hydration bond

Answer explanation

H2O is water, which is a covalent compound! It will be made of covalent bonds!

When you are heating up water, what bonds are you breaking in order to turn it into a gas?

• Ionic bonds

• Covalent bonds

• Intermolecular bonds

Answer explanation

While water is made of covalent bonds, it is the intermolecular bonds that are broken when we are trying to boil it. That is why the boiling point is generally low for simple covalent structures because intermolecular bonds are weak!

Why is the melting point of diamond very high?

• There are many ionic bonds in diamonds, which are very strong and require a lot of energy to break.

• There are many covalent bonds in diamonds, which are very strong and require a lot of energy to break.

• There are many intermolecular bonds in diamonds which are very strong and require a lot of energy to break.

Answer explanation

Diamond is a giant covalent structure which means it doesn't have intermolecular bonds to break when we are trying to melt it. We instead, are trying to break the covalent bonds, which are very strong and require a lot of energy to break!

Why is the melting point for NaCl high?

• It contains a lot of ionic bonds, which are strong. Therefore, a lot of energy is require to break the bonds.

• It contains a lot of covalent bonds, which are strong. Therefore, a lot of energy is require to break the bonds.

• It contains a lot of intermolecular bonds, which are strong. Therefore, a lot of energy is require to break the bonds.

Which of the following will conduct electricity? Explain why.

• NaCl(s) because it has free moving electrons.

• NaCl(aq) because it has free moving electrons.

• NaCl(l) because it has free moving ions.

• Graphite because it has free moving ions.

Answer explanation

NaCl(aq) can also conduct electricity but it's not because it has free moving electrons, it is because it has free moving ions. Graphite can also conduct electricity but not because it has free moving ions, it has free moving electrons. Therefore, NaCl(l) is the only correct answer as it can conduct electricity because it has free moving ions.

This substance has a high melting and boiling point and cannot conduct electricity in any state. What is the identity of this substance?

• NaCl

• H₂O

• Diamond

• Graphite

Draw the dot and cross diagram of HCl (You only need to draw the valence electrons)

Answer explanation

Hydrogen has 1 valence electron and chlorine has 7. Don't forget to show the lone pairs on chlorine as well to get the full mark! 1 mark for the sharing electrons and 1 mark for the lone pairs!

Draw the dot and cross diagram of NaCl

Answer explanation

Sodium loses 1 valence electron to chlorine. Chlorine gains 1 valence electron and now has 8. Both sodium and chlorine are now stable with sodium being positively charged and chlorine being negatively charged.