Ions Ionic Bonding Ions When an atom gains

Ions & Ionic Bonding

Ions • When an atom gains or loses an electron, it becomes an ION. • Atoms that gain electrons are called anions. (-) • What atoms usually gain electrons? NONMETALS! • Atoms that lose electrons are called cations. (+) • What atoms usually lose electrons? METALS!

Ions • Here is a simple way to remember which is the cation and which is the anion: + This is Ann Ion. She’s unhappy and negative. + This is a cat-ion. He’s a “plussy” cat!

Ionic Radius: Review’d • Cations are always smaller than the original atom. • The entire outer energy level is removed during ionization. • Conversely, anions are always larger than the original atom. • Electrons are added to the out energy level.

Cation Formation Effective nuclear charge on remaining electrons increases. Na atom 1 valence electron 11 p+ Valence elost in ion formation Remaining e- are pulled in closer to the nucleus. Ionic size decreases. Result: a smaller sodium cation, Na+

Anion Formation Chlorine atom with 7 valence e - Effective nuclear charge is reduced and the e- cloud expands. 17 p+ A chloride ion is produced. It is larger than the original atom. One e- is added to the outer shell.

Ionic Bonds • Ionic bonds are a special kind of chemical bond. • Chemical bonds – they are like glue, they hold atoms together! • Ionic bonds hold together metal & nonmetal atoms. • If it is not a bond between a metal & nonmetal… it is NOT ionic.

Ionic Bonding • What happens when an atom becomes and ion? • It becomes charged! • What do oppositely charged objects like to do? • ATTRACT! • Ionic bonds are held together by electrical charge.

How to: Steps for Success • • 1) Start with separate atoms (a metal & nonmetal) 2) Decide which atom will lose and which will gain an electron 3) Move the electron over, assign charges to your new ions 4) Ions have opposite charges… so stick them together!!