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):

• Metals
• React with non-metal elements to form ionic compounds
• Produce ions with a 1+ charge

Group 7 Elements (the halogens):

• Non-metals
• 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.