Proton = +
Neutron = 0
Electron = -
- Non metal + non metal = covalent (sharing electrons)
- Metal + non metal = ionic (transferring electrons)
- Metal + metal = metallic (delocalised electrons)
When an element looses electrons it becomes positively charged.
When an element gains electrons it becomes negatively charged..
This is because protons outweigh electrons.
Group 1 alkali metal + Group 7 halogen = +ve metal ion + -ve halide ion
The metal atoms lose electrons to form positive ions. The non metal atoms gain electrons to for negitive ions. Opposites attract and this is ionic bonding.
An ionic compound is a giant structure or lattice. They are held together by strong electrostatic forces of attraction that act in all directions.
Represented by dot and cross diagrams.
The charges in the ionic compound always cancel each other out.
- 2 non metals sharing electrons
- Very strong bonds
- Number of covalent bonds and an atom forms depends on the number of electrons it needs to achieve stable electronic structure
- Some have giant covalent structures, as covalent bonds are only between 2 atoms. Some substances are made of several molecules
Examples: Hydrogen, Chlorine, Oxygen, Methane, Ammonia, Hydrochloric acid, Water
- Giant structure
- Atoms in metals are all the same size and arranged in regular layers
- Electrons in the outer shell of the atoms are delocalised
Delocalised electrons can move about freely between the positively charged ions. This acts as a lattice of positive ions to hold the structure together, as the negitive electrons strongly attract the positively charged ions with an electrostatic force.