1. Chemical Bonds

2. Ionic Bond

3. Ions Ion - Is an atom or group of atoms that has an electric charge When an atom loses an electron it becomes positively charged. When an atom gains an electron it becomes negatively charged.

4. Ionic Bonds Ionic bonds are formed as a result of attraction between positive and negative ions. Ionic compounds consists of positive and negative ions example: Sodium Chloride NaCl

5. IONIC BONDING When an atom of a nonmetal takes one or more electrons from an atom of a metal so both atoms end up with eight valence electrons

6. IONIC BONDING IS THE COMPOUND AN IONIC COMPOUND?METAL NONMETAL SUBSCRIPTS

7. IONIC BONDING Metals will tend to lose electrons and become POSITIVE CATIONS Normal sodium atom loses one electron to become sodium ion

8. IONIC BONDING Nonmetals will tend to gain electrons and become NEGATIVE ANIONS Normal chlorine atom gains an electron to become a chloride ion

9. Properties of Ionic Compounds 1. Hard, brittle solids 2. Have high melting points 3. Crystalline structure - A regular repeating arrangement of ions in the solid. 4. Solutions of ionic compounds conduct electric current.

10. Crystalline structure + + ++ + + + + + - - - - - - - - - The POSITIVE CATIONS stick to the NEGATIVE ANIONS, like a magnet.

11. Chemical Formulas and Names To write the formula of an ionic compound you must make sure the compound’s overall charge is zero. (listen to explanation). To name an ionic compound you should name the positive ion (metal) first followed by the name of the negative ion (nonmetal). Example: Magnesium Oxide. Notice the ending of negative ion it is always – ide HINT- THE METAL WILL ALWAYS COME FIRST!

12. Chemical Formula Written in the same order as the name. Use subscripts to indicate if more than one ion is needed to complete the bond. Ex: o Sodium Oxide = Na 2 O

13. Metallic Bonds Metal atoms can bond to other metal atoms in what we call, naturally, metallic bonding. When these atoms come together they actually form a mixture called an alloy, not a compound.

14. Metallic Bonding = Potluck Dinner When you arrive at a potluck dinner you place your dish with everyone else’s dish, you are free to eat whatever you want regardless of who brought it. Metallic bonding is similar to this. Metals bring their electrons to the party and all metals at the party can share them to complete there outer shell making everyone at the party “happy”!

15. Naming Metallic Bonds There is not yet a systematic way of naming alloys like those you have learned for naming covalent and ionic compounds. In part, this is because alloys are not compounds, their composition is variable and their names need to reflect that. Generally, we use common names like brass, bronze, or steel or technical names like alnico I, alnico II, chromium steel or high carbon steel. You will not be held responsible for naming alloys in this course.