Understanding Ions and Ionic Bonding Fundamentals

1. Ions & Ionic Bonding

2. 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!

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

4. 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.

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

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

7. 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.

8. 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.

9. 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!!