1. Lesson 3.05 Ionic Bonding and Writing Formulas

2. Vocabulary Terms Ions – An atom or a group of atoms that has acquired a charge by gaining or losing one or more electrons. Cation – An ion or group of ions having a positive charge. Anion – A negatively charged ion. Polyatomic Ions - formed from two or more atoms that have been bonded together that carry a positive or negative charge. Monoatomic Ions – an ion consisting of one or more atoms of a single element

3. Vocabulary Terms Ionic Bonding – A chemical bond that is due to transfer of electrons between a metal and a nonmetal. Ionic Compounds - A compound composed of positive and negative ions that are combined in a ratio where the positive and negative charges cancel out. Compound formed through Ionic bonding. Formula Unit - The formula of an ionic compound that represents the simplest whole number ratio of ions in the compound, not the actual number of each ion present in the crystal.

4. Ions Cation – an ion that has lost electron/s becomes a positively charged particle. Anion – an ion that has gained electron/s becomes a negatively charged particle. Ex: Cation - electron - Anion

5. Charge of an atom Ex: When sodium atom loses an electron, it becomes a sodium ion(Na +1). Since it has lost only one electron, it has a charge of +1. Na atom – electron = Na+1(cation) When a chlorine atom gains an electron, it forms a chloride ion(Cl-1). Since it has one extra electron, it has a charge of -1. Cl atom + electron = Cl-1(anion)

6. Periodic Table- Charges

7. Polyatomic Ions- Charges

8. Writing Formula of Ionic Compounds Steps: 1) Identify the charge of each of the ions in the compound. 2) The positive ion is always written first, followed by the negative ion. 3) Determine the ratio of positive to negative ions needed to make the compound neutral. 4) Make sure that the subscripts represent the lowest whole number ratio for the ionic compound. 5) Check your work: Make sure that the net charge of the formula is zero.

9. Ionic Compounds Examples: Formula Unit

10. Let’s Practice 1)Aluminum and Oxygen(Aluminum oxide) 2) Calcium and Nitrate(Calcium Nitrate)

11. More Practice! 3) Magnesium and Bromine(Magnesium bromide) 4) Sodium and Sulfate(Sodium Sulfate)