1. 2.6 and 2.7 – Molecular and Ionic Compounds

2. Molecules and Chemical Formulas Atoms bind to other atoms to form molecules Ionic Bonding: Giving and taking electrons (Metal- nonmetal bond) Covalent Bonding: Sharing electrons (nonmetal- nonmetal bond) There are gasses that are bound to themselves as elements: Hydrogen = H 2 Nitrogen = N 2 Oxygen = O 2 Fluorine = F 2 Chlorine = Cl 2 Bromine = Br 2 Iodine = I 2 You need to memorize these!

3. The Hockey Stick and Puck

4. Formulas We can represent molecules with molecular and empirical formulas. Molecular Formula = shows actual number of atoms in a molecule. Empirical Formula = shows ratio of atoms in a molecule.

5. CLASS EXAMPLE Determine the empirical formula for the following compounds: 1. C 6 H 12 O 6 2. N 2 O

6. TRY IT OUT! 1.Determine the empirical formula of the following compound: B 2 H 6 2.Is this a molecular or empirical formula: N 4 O 6 ?

7. Ions and Ionic Compounds Recall, an ion forms when an atom gains or loses electrons Elements/compounds will gain or lose electrons in order to achieve a full outer valence shell. Cation – A positively charged ion that forms when electrons are lost Anion – A negatively charged ion that forms when electrons are gained. ClCl - NaNa + Gains 1 electron, so it ends with a negative 1 charge

8. IONIC ATTRACTION Just like opposite poles of a magnet attract, oppositely charged ions attract. Here, our positively charged Sodium Ion and negatively charged Chlorine Ion are attracted. They remain ions, but stick together in a lattice (3D grid pattern) as other ions join them. Cl - Na + Cl - Na + Cl - Na + Cl -

9. Determining Ionic Formulas To determine the ionic formula that forms between two ions you need to do a few steps before beginning: 1.Make sure you have both a metal and non- metal. This indicates that an ionic bond will form 2.If a polyatomic ion is present, then make sure to put parentheses around it before beginning

10. Na + O 2- Na 2 O

11. K 2+ NO 3 - K(NO 3 ) 2

12. CLASS EXAMPLE Determine the formula when the following join in an ionic bond: 1. Sodium and oxygen 2. Potassium and phosphate

13. TRY IT OUT! 1.Lithium and fluorine 2.Ammonium and sulfate