Topic 2: Bonding and Structure
BONDING
1. know that ionic bonding is the strong electrostatic attraction between
oppositely charged ions
Ionic bonding: The strong electrostatic attraction between oppositely charged ions.
Ionic bonding occurs between a positively and a
negatively charged ion e.g. NaCl is made up of Na +
and Cl- ions. One electron is transferred from the
outer electron on the Na to the outer shell on the Cl.
An ionic compound is a giant lattice meaning it
cannot have molecular formula, so NaCl just tells
you the ratio of atoms in the compound.
2. understand the effects that ionic radius and ionic charge have on the
strength of ionic bonding
Factors affecting strength of ionic bonds:
Ionic charge
The greater the charge on an ion, the stronger the electrostatic force of attraction. E.g. the
boiling point of MgO is higher than that of NaCl as Mg and O have a 2 +/- charge so more energy is
required to break the bond.
Ionic radii
Smaller ions can pack closer together than larger ions meaning there is greater attraction
between the oppositely charged ions. The size of an ion is determined by the number of electron
shells and atomic number. The more electron shells the weaker the bond is. E.g. NaCl has a
higher melting point than NaI because the iodine ion is larger as it has more electron shells, so
the ionic radius is larger. This makes the ionic bond weaker, requiring less energy to be broken.
If there are different ions with the same number of electrons it is the ion with the higher atomic
number that has a weaker bond, e.g. Al3+ has a smaller ionic radius than F-.
3. understand the formation of ions in terms of electron loss or gain
Ions are formed by the loss and gain of electrons. The metal loses electrons from its outer shell
which are gained by the non-metal to form two charged ions. This involves a redox reaction
where the metal is oxidised, and the non-metal is reduced.
4. be able to draw electronic configuration diagrams of cations and anions
using dot-and-cross diagrams
Dot and cross diagrams show the electron transfer in ionic bonding:
5.
understand reasons for the trends in ionic
radii down a group and for a set of isoelectronic ions, e.g. N 3– to Al3+
BONDING
1. know that ionic bonding is the strong electrostatic attraction between
oppositely charged ions
Ionic bonding: The strong electrostatic attraction between oppositely charged ions.
Ionic bonding occurs between a positively and a
negatively charged ion e.g. NaCl is made up of Na +
and Cl- ions. One electron is transferred from the
outer electron on the Na to the outer shell on the Cl.
An ionic compound is a giant lattice meaning it
cannot have molecular formula, so NaCl just tells
you the ratio of atoms in the compound.
2. understand the effects that ionic radius and ionic charge have on the
strength of ionic bonding
Factors affecting strength of ionic bonds:
Ionic charge
The greater the charge on an ion, the stronger the electrostatic force of attraction. E.g. the
boiling point of MgO is higher than that of NaCl as Mg and O have a 2 +/- charge so more energy is
required to break the bond.
Ionic radii
Smaller ions can pack closer together than larger ions meaning there is greater attraction
between the oppositely charged ions. The size of an ion is determined by the number of electron
shells and atomic number. The more electron shells the weaker the bond is. E.g. NaCl has a
higher melting point than NaI because the iodine ion is larger as it has more electron shells, so
the ionic radius is larger. This makes the ionic bond weaker, requiring less energy to be broken.
If there are different ions with the same number of electrons it is the ion with the higher atomic
number that has a weaker bond, e.g. Al3+ has a smaller ionic radius than F-.
3. understand the formation of ions in terms of electron loss or gain
Ions are formed by the loss and gain of electrons. The metal loses electrons from its outer shell
which are gained by the non-metal to form two charged ions. This involves a redox reaction
where the metal is oxidised, and the non-metal is reduced.
4. be able to draw electronic configuration diagrams of cations and anions
using dot-and-cross diagrams
Dot and cross diagrams show the electron transfer in ionic bonding:
5.
understand reasons for the trends in ionic
radii down a group and for a set of isoelectronic ions, e.g. N 3– to Al3+
