1. Counting Atoms

2. DO NOW MONDAY Begin your Pre-Test over Chemistry Unit Part 2.
When you finish, turn it in to the side cart and pick up a sheet of notebook paper.
Number the notebook paper 1-36.

3. TODAYS PLAN
To demonstrate Mastery of Chemistry Part 1 Learning Targets on a written Exam.
TODAYS DO
We will do retake and/or enrichment over Chemistry Part 1 Learning Targets.
Made 80% or Greater, you will get a ChromeBook, go to my Seventh Grade Science page, click on Periodic Table Enrichment, and play the games on the websites located there.
Made less than 80%, you will be using your notes and asking the teacher questions to redo the questions you missed on the Chemistry Part 1 Test.

4. DO NOW TUESDAY
Tell what you think is the difference between an element and a compound.

5. TODAYS PLAN
Distinguish between symbol and formula.
Conclude the number of atoms of each element that exists in a molecule/compound.
Distinguish between elements and compounds according to their properties (original vs. after a chemical change)
Differentiate between the model of a compound versus a model of an element.
TODAYS DO
We will do guided notes about elements, compounds, and compound formulas.
We will practice counting the atoms in compound formulas and drawing models of compounds

6. Elements Are made of atoms Are found on the periodic table
Have chemical SYMBOLS

7. Element Chemical Symbol
Symbol for the element on the Periodic Table
Made up of ONE OR TWO letters
First letter is always capitalized
Second letter, if present, is lowercase
Element
Chemical Symbol
Carbon C
Aluminum Al
Fluorine F
Copper Cu

8. Compounds Made up of two or more elements chemically combined
This means the elements were combined by a chemical change.
The atoms of the atoms are held together by chemical bonds-a “stickiness” between the atoms that holds them together.
The compound is a NEW substance and has different properties than any of the elements that are in the compound.
Compounds have chemical FORMULAS.

9. Examples of Compounds Element + Element = Compound
Sodium (Na) + Chlorine (Cl) = Sodium Chloride (NaCl) =
Explosive metal + green poison gas = table salt (edible)

10. Examples of Compounds Element + Element = Compound
Hydrogen (H) + Oxygen (O) = Water (H2O) =
Colorless flammable gas + colorless flammable gas = colorless liquid (edible) (nonflammable)

11. COMPOUND CHEMICAL FORMULAS
All compounds have Chemical FORMULAS.
These formulas tell us WHAT ELEMENTS are in the compound
AND
HOW MANY atoms of each element are in the compound

12. COMPOUND CHEMICAL FORMULAS
Tell us:
What ELEMENTS
AND
2. HOW MANY ATOMS

13. Practice
Tell whether each of the following is an element or a compound:
I N
Br Ba
KCl CaO
NaOH Mn
K2CO N2O3
Element
Element
Element
Element
Compound
Compound
Compound
Element
Compound
Compound

14. Counting Atoms
The symbol of an element represents ONE atom of that element
CO = 1 C and 1 O
A subscript in a chemical formula is a number written at the lower right corner after the symbol for the element. It represents the number of atoms of an element in a compound (when there is more than one atom of that element.
Na2CO3 = 2 Na 1 C and 3 O
2 atoms total
6 atoms total

15. Counting Atoms: Practice
Tell which elements are in the compound AND how many atoms of each element there are:
NaHCO3
N4H3

16. Counting Atoms
When there is a subscript written outside parentheses in a chemical formula, the subscript MULTIPLIES by all of the elements inside of the parentheses.
(SO4)3 =
1 x 3 S = 3 S
4 x 3 O = 12 O
15 atoms total

17. Counting Atoms
A coefficient is a number written in front of a chemical symbol.
The coefficient also MULTIPLIES by the element and/or subscript.
Example 1: 4 H2O =
Example 2: 2 (NH4)3PO4 =
4 x 2 H = 8 H
12 atoms total
= 4 x 1 O = 4 O
2x 1 N = 2 N
= 2 x 4 x 3 H = 24 H
= 2 x 1 P = 2 P
36 atoms total
= 2 x 4 O = 8 O

18. Reading Models of FormulasNa Cl
NaCl
H2O

19. Reading Models of FormulasC O O Ca
CaCO3

20. Drawing Models of Formulas
Na2Cl2
2H2O Cl Cl Na Na