Formation of Ions
Ions form when an atom loses or gains an electron.
Postive Ions: Metal/Hydrogen atoms lose electrons to form positive ions. Example: Sodium losing an electron to become a Na+ sodium ion.
Negative Ions: Non-metal atoms gain electrons to form negative ions. Example: Chlorine gaining an outer electron to form a Cl- chlorine ion.
- The number of charges on a positve ion is the same as the group of the element.
- The number of charges on a negative ion is 8 minus the group number of the element.
Example: Group 1 (Charge on ion of +) / Group 6 (Charge on ion of 2-)
Ionic compounds contain positive and negative ions, formed when atoms transfer electrons.
Group 1 Elements (alkali metals):
- React with non-metal elements to form ionic compounds
- Produce ions with a 1+ charge
Group 7 Elements (the halogens):
- React with metal elements to form ionic compunds
- Produce ions with a 1- charge
Formationof ionic compounds: Group 1 elements react with Group 7 elements to produce ionic compounds. Example: Na + Cl --> Na+Cl- (Ions)
The electron from the highest occupied energy level of a Na atom is transferred to the highest occupiued energy level of a Cl atom, forming the Na+ & Cl- ions.
An ionic compound is a giant structure of ions that are held in a regular arrangement (lattice).
Ionic bonds are strong electrostatic forces of attraction between oppositely charged ions; acting in all directions in the ionic lattice - which hold is together.
When representing positive ions:
- Metal atoms lose one or more electrons to form positive ions.
- The number of charges is the same as the group number.
When representing negative ions:
- Non-metal atoms gain one or more electrons to form negative ions.
- The number of charges is equal to 8 minus the group number.