1. CATALYST (10 minutes, individual work):
Assignment #4 Valence Electrons LO: Describe patterns on periodic table. Predict valence electrons for a given element. EQ: How do you predict the number of valence electrons for a given element?
LEVEL ZERO VOICE
CATALYST (10 minutes, individual work):
1. Draw a B-2 ion. Label protons, neutrons, nucleus, electrons & electron cloud.
Calculate the atomic number and atomic mass.
2. Draw 3 isotopes for Carbon
Calculate the atomic number and atomic mass for each
AGENDA
Valence Exploration
Class Discussion
Review for test
HOMEWORK
1. Finish processing tasks

2. Every neutral atom has a unique number of electrons
Balance out #protons to make it neutral charge   

3. Valence electrons – electrons in the outer shell of an atom, the atom wants 8 valence electrons  

4. Exception! H and He only need 2 valence
Bond – when two/more atoms share valence electrons so they both have 8 valence electrons
Exception! H and He only need 2 valence

6. Elements are made of one type of atom
He or H2 or O2
Sodium is an element because it only contains sodium atoms
Gold is an element because it only contains gold atoms
Oxygen gas (02) is also an element because it only has one type of atom

7. Bonded atoms form molecules
molecule: a neutral particle that forms as a result of electron sharing
EX: H2O: “H two O” or water
EX: NaCl: “N A C L” or Sodium chloride or salt
can be formed by two of the SAME atom
Ex: O2: “O two” or oxygen gas
H2: “H two” or hydrogen gas

8. Compound: a pure substance that contains molecules of the same type
H20 (water), NaCl (salt), carbon dioxide (CO2)
Different from an Element
Gold, diamond, helium
He or H2 or O2

9. Compounds have different properties than their individual components
Chlorine gas + sodium metal = table salt
(write down the discussion on the board)

10. Properties of Na (sodium) :
Metal
Grey color
Soft (can cut it with butter knife)
poisonous

11. Properties of Cl (chlorine) :
Yellow
Gas
poisonous

12. But we know the properties of the compound are different from the properties of the parts of the compound so…………..
Chlorine (not edible) + sodium (not edible) = SALT (delicious!!)

13. RECAP:
Putting ATOMS together makes MOLECULES.
If the atoms aren’t all the same in the molecule, it is a COMPOUND.
Because a molecule can be an ELEMENT (O2)

14. Writing molecules:

15. Writing molecules: Coefficient: how many molecules there are
Subscript: how many atoms there are in the molecule (small number)

16. Element: all atoms in molecule are the same element (H2, O2)
Compound: different atoms in molecule (H2O, CO2)
Mixture of elements: a mix of molecules that are elements
Mixture of compounds: a mix of molecules that have different atoms
Mixture of elements and compounds