why do ions form ?
to achieve a full outer shell
how do ions form?
an atom gains or loses electrons to form ion with full outer shell
what do metal atoms do?
they lose electrons to form a positive ion called cations
what do non-metals do?
they gain electrons to become negative ions called anions
what happens in ionic bonding?
electrons lost by the metal atom transfers to the non-metal atom.
this transfer allows both atoms to achieve a full outer shell, resulting in the formation of stable ions
practise drawing a dot and cross diagram
what about transition metals?
have partially filled d sub-shells, enabling to form multiple ions with different charges
what happens when transition metals undergo ionisation?
the 4s electrons are lost before the 3d electrons. The 3d and 4s electron shells in transition elements have very close energy levels, making it easy to remove electrons from both shells sequentially. This is why many transition metals can form ions with different charges (oxidation states
what are compound ions?
atoms from 2 or more elements chemically bonded together, resulting in an overall charge
what are important compounds to know?
nitrate ion = NO3-
carbonate ion = CO32-
sulfate ion = (SO42-)
hydroxide ion = (OH-)
ammonium ion = (NH4+)
practise determining the formula of ionic compounds
what is an ionic bond ?
the electrostatic force of attraction between oppositely charged ions, usually a metal and a non metal
the bonds are very strong
when ions bond this way and ionic compound is formed
what is the structure of ionic compounds?
have giant lattice structures where positive and negative ions pack together
what are the key features of a giant lattice?
- each ion is electrostatically attracted to ions of the opposite charge in all directions
- it takes significant energy to overcome these strong electrostatic forces between ions
what are the properties related to an ionic compound?
- high melting and boiling points
- conduct electricity when molten or solution
- do not conduct electricity as solids
- dissolve in water
why high melting and boiling points?
- strong electrostatic attractions between positive and negative ions
- a lot of energy is required to break them
why conduct electricity when molten or in solution?
ions can move freely and carry electric charge through the liquid
why cant conduct electricity when solid?
ions are locked in place and unable to move to carry electric charge
why dissolve in water ?
water molecules= polar
attract the charged ions in the lattice, via ion- dipole forces, pulling them away from lattice and dissolving the structure
