1. Bonding

2. Essential Question
Why do some elements bond with some, but not others? Assessment: Lab report

3. The octet rule
Elements become stable by achieving same configuration of valence electrons as one of the noble gases (noble gas configuration)
When atoms collide, outer electrons rearrange to achieve stable octet of valence electrons
How do they rearrange?
1. Transfer valence electrons between atoms
2. Share valence electrons between atoms

4. Ionic bond
Ion = atom that has a charge because of loss or gain of electrons
Electrons transferred from one atom to another

5. Ionic bond
Electrons transferred from one atom to another

6. Bonding patterns Ionic bond Covalent bond Electrons transferred
Electrons shared
Between atoms that have different electronegativity (high and low)
Between atoms that have high electronegativity
Metals and non metals
Non metals and non metals

7. Electronegativity
Measure of the ability of an atom in a chemical compound to attract electrons
The atom with higher electronegativity will pull on the electrons more strongly that other atoms will

8. Ionic bond
Oxidation number = charge on an atom
Switcheroo!

9. Ionic bond Short quiz on ionic bonding next class. Know:
Ionic vs covalent
Charges of different elements on the periodic table
How to form compounds
How to name compounds
Resources: Ionic bonding notes & puzzle activity

10. Lewis Dot Diagram
Illustrates valence electrons as dots around the chemical symbol of an atom.

11. Covalent bond Electrons shared between atoms
Hydrogen requires one more e- to have same configuration as helium
Oxygen requires two more e- to have the same configuration as neon

12. Covalent bond

13. Covalent bonds
More than two electrons can be shared

14. Classes of Elements
Metals – elements that have luster, conduct heat and electricity (e.g. copper jewelry, polished silverware)
Nonmetals – most are gas at room temp, do not conduct electricity, poor conductor of heat than metals (e.g. oil – carbon rich)
Metalloids – semiconductor (does not conduct electricity as well as metal but conducts better than nonmetal) (e.g. silicon in microchips of electronics)

15. Bonding patterns Ionic bond Covalent bond Solids at room temperature
Can be solid, liquids or gases at room temperature
Higher melting point than covalent compound – why?
Low melting point than ionic compounds
Conduct electric current – why?
Do not conduct electric current