1. Chapter 4 Bonding

2. Metal + Nonmetal A nonmetal will take electrons from a metal. This transfer of electrons results in ions. The type of bond formed is an ionic bond. Na + Cl → NaCl (sodium chloride salt) Show this process with electron-dot structures

3. 2 Li + S → Li 2 S 2 Li + S → Li 2 S Show this process with electron-dot Arrangement of ions in a salt crystal http://www.avogadro.co.uk/structure/chem struc/ionic/g-ionic.htm http://www.avogadro.co.uk/structure/chem struc/ionic/g-ionic.htm http://www.avogadro.co.uk/structure/chem struc/ionic/g-ionic.htm Complete C-4 Chemical Bonding Worksheet.

4. Oxidation number The small numbers above the elements on the chart are oxidation numbers. This is the charge on the ion formed after an element has gained or lost electrons. Metals will always have a positive oxidation number. Non-metals will always have a negative oxidation number when combined with metals.

5. Oxidation numbers can be used to predict formulas of compounds. Write the symbols of the elements being combined with the metal written first. Write the oxidation numbers above the symbols. Use the criss-cross method to determine formula. Examples: Complete C-4 worksheet 2

6. Covalent bonding Two nonmetals will compete for valence electrons. Neither nonmetal can win this competition so they are forced to share electrons. F + F → F 2 Show electron-dot for the above reaction. One pair of shared electrons is a single bond.

7. Two shared pairs of electrons is a double bond. O + O → O 2 O + O → O 2 Three pairs of shared electrons is a triple bond. N + N → N 2 N + N → N 2

8. Polar Covalent Bond Polar covalent bonds result from unequal sharing of electrons. The shared electrons spend more time near one atom than the other. The closer to F an element is the better it is at competing for electrons This puts a partial charge on each atom. http://www.beyondbooks.com/psc92/3c.asp Polar molecules attract each other and have higher boiling and melting points.

9. Metallic Bond A metal can form a bond with other metal atoms by sharing valence electrons between them. All valence electrons are shared by all metal atoms. Valence electrons are not held tightly and can move through the metal (conduct electricity)