Structure 2.1 Flashcards
What elements form cations?
Ones with low or relatively low ionisation energies. (Groups 1, 2 and 13) as well as hydrogen and transition metals.
What forms anions?
Formed by non-metals that gain electrons to form a full outer shell
Isoelectronic
Two different species with the same electron configuration
Transition element
An element with a partially filled d subshell. It can form multiple ions with different charges.
What happens when the first row transition elements are ionised?
The 4s electrons are lost before the 3d electrons
How are ions arranged in the solid state?
In a lattice
Ionic bond
the sum of all the electrostatic attractive and repulsive forces between all the ions in the lattice.
Lattice enthalpy
Tells us how strong the ionic bonds are in a particular ionic lattice.
The ___ the ion, the ___ the lattice enthalpy
smaller, greater
The ___ the charge, the ___ the lattice enthalpy
greater, greater
Properties of ionic compounds
- High melting and boiling points
- Electrical conductivity
- Solubility
Why do ionic compound have high melting and boiling points?
Considerable energy is required to break the lattice into the liquid state and then vaporise into the gaseous state due to the strong electrostatic forces of attraction.
Electrical conductivity of ionic compounds
In the solid state ionic compounds do not conduct electricity as there are no free electrons and the ions are in fixed positions and so cannot move towards electrodes. In the molten state they can conduct electricity as ions are now free to move and carry the charges.
Solubility of ionic compounds
Many ionic compounds are soluble in water. The water causes the ions to become hydrated (exothermic process). If this is higher than the lattice energy the salt dissolves in water.
What does it mean for an ion to become hydrated?
Hydration is the process by which ions in a solution become surrounded by water molecules. The Cations are attracted to the oxygen atoms of water molecules, as the oxygen end is partially negative. The anions are attracted to the hydrogen atoms of water molecules, as the hydrogen end is partially positive.
