Define the term ionic bonding in terms of electrostatic forces.
Ionic bonding is the strong electrostatic force of attraction between oppositely charged ions.
Describe the structure of an ionic compound, explaining how the particles are arranged.
Ionic compounds form a giant ionic lattice structure, which is a regular, repeating three-
dimensional arrangement of alternating positive and negative ions. The ions are held in fixed
positions within this lattice.
Why do ionic compounds typically have high melting and boiling points?.
Large amounts of energy are needed to overcome the strong electrostatic forces of attraction
that hold the ions together within the giant ionic lattice.
Under what conditions can ionic compounds conduct electricity, and why?.
Ionic compounds can conduct electricity when they are molten (liquid) or dissolved in a solution.
In these states, the ions are free to move and carry an electrical charge. When solid, the ions are
fixed in position and cannot move, so the compound does not conduct electricity.
Explain what is meant by a single covalent bond.
A single covalent bond is a chemical bond formed when two non-metal atoms share one pair of
electrons to achieve a full outer shell.
What is a coordinate bond (or dative covalent bond)?
A coordinate bond is a type of covalent bond where one atom provides both of the shared
electrons.
How is a coordinate bond represented in a diagram?
A coordinate bond is represented by an arrow that points from the atom donating the lone pair
of electrons to the electron-deficient atom that is accepting the pair.
Explain why, once formed, a coordinate bond is no different from a normal covalent bond.
Once formed, the electrons in a coordinate bond are shared between the two atoms, and the
bond's nature is the same as any other covalent bond. The only difference is in the origin of the
electrons, not the properties of the bond itself.
Give an example of a species that contains a coordinate bond and explain how it is formed.
The ammonium ion. It is formed when a lone pair of electrons on the nitrogen atom in an
ammonia (NH3) molecule is donated to a hydrogen ion (H+), which has an empty orbital.
Describe metallic bonding in terms of delocalised electrons and positive ions.
Metallic bonding is the strong electrostatic force of attraction between a lattice of positive metal
ions and a “sea” of delocalised electrons.
Why are metals good conductors of electricity?.
Metals contain delocalised electrons that are free to move throughout the structure. When a
voltage is applied, these mobile, charged particles can carry an electrical charge, creating a
current.
Explain why metals are malleable and ductile.
Metals consist of layers of positive ions. These layers can slide over one another when a force is
applied. The metallic bond is maintained because the delocalised electrons can move with the
layers, so the metal can be bent (malleable) or drawn into wires (ductile) without breaking.
How does the strength of metallic bonding vary with the size of the metal ion and the number
of delocalised electrons?.
○ Ion size: The smaller the metal ion, the stronger the metallic bonding, as the delocalised
electrons are closer to the positive nucleus, resulting in a stronger attraction.
○ Number of delocalised electrons: The more delocalised electrons per atom, the stronger
the metallic bonding, as there is a greater total electrostatic attraction between the ions
and the sea of electrons.
Rank the following intermolecular forces from weakest to strongest:
- permanent dipole-dipole,
-induced dipole-dipole (van der Waals),
-hydrogen bonding.
- Induced dipole-dipole (van der Waals) (weakest)
- Permanent dipole-dipole
- Hydrogen bonding (strongest)
Explain how induced dipole-dipole forces arise in non-polar molecules.
Induced dipole-dipole forces (also known as London or van der Waals forces) arise due to the
random movement of electrons. At any given moment, the electrons may be momentarily
unevenly distributed on one side of a molecule, creating an instantaneous temporary dipole. This
temporary dipole can then induce a corresponding dipole in a neighbouring molecule, leading to
a weak electrostatic attraction.
What are the two conditions necessary for hydrogen bonding to occur?.
Hydrogen bonding occurs when:
1. A hydrogen atom is covalently bonded to a highly electronegative atom (nitrogen,
oxygen, or fluorine).
2. There is a lone pair of electrons on a nearby highly electronegative atom (nitrogen,
oxygen, or fluorine) in an adjacent molecule.
Explain the trend in boiling points of the halogens down Group 7.
The boiling point of the halogens increases down Group 7. This is because the molecules get
larger and have more electrons, leading to stronger induced dipole-dipole forces between them.
More energy is therefore required to overcome these intermolecular forces.
