• Page 30: Counting Elements and Atoms Practice

• Page 31: Review of Elements and Compounds

Review of Elements and Compounds

Page 31H2O

•C6H12O6

S

Elements• Elements--- a pure substance (made up

of ONLY ONE type of atom) that cannot be broken down into smaller parts

• Elements are found on the Periodic Table

• To count elements, COUNT CAPITAL LETTERS!

Compound• Compound--- two or more elements that are CHEMICALLY

COMBINED

• H2O (2 atoms Hydrogen and 1 atom Oxygen)

• CaCO3 (1 atom Calcium, 1 atom Carbon, and 3 atoms Oxygen)

• CO2 (1 atom Carbon and 2 atoms Oxygen)

Atoms vs. Elements

• Atoms = particles–The number of atoms is the number of total

particles (counting the subscripts AKA little numbers at the bottom)

• Element = the type of pure substance–The number of elements is the number of capital

letters or symbols in your formula.

Element VS Compound

Zn

Mg

HP

Li

OHH

ClNa

OO

C

Is it an element or compound?

Ask Yourself?

Is there more than one type of element?

YES NO

COMPOUND

ELEMENT

• Page 30: Counting Elements and Atoms Practice

Glue in the example. To the side of the box or below it, include:The number of elements present & their nameThe number of atoms of each elementThe TOTAL number of atoms in all.

Compound Elements Present # of Atoms each Total # of atoms

1. CaCO3 3: Calcium, Carbon, Oxygen

1 Calcium1 Carbon3 Oxygen

5 total atoms

2. C9H8O4

3: Carbon, Hydrogen, Oxygen

9 Carbon8 Hydrogen4 Oxygen

21 total atoms

3. Mg(OH)2

3: Magnesium, Oxygen, Hydrogen

1 Magnesium2 Oxygen2 Hydrogen

5 total atoms

4. C6H4Cl2

3: Carbon, Hydrogen, Chlorine

6 Carbon4 Hydrogen2 Chlorine

12 total atoms

Compound # of Elements Present

# of Atoms of each Total # of Atoms

5. C2H4O2

3 Elements: Carbon, Hydrogen, Oxygen

2 Carbon4 Hydrogen2 Oxygen

8 total atoms

6. C7H5(NO2)3

4 Elements: Carbon, Hydrogen, Nitrogen, Oxygen

7 Carbon5 Hydrogen3 Nitrogen6 Oxygen

21 total atoms

7. Ca(H2PO4)2

4 Elements: Calcium, Hydrogen, Phosphorus, Oxygen

1 Calcium4 Hydrogen2 Phosphorus8 Oxygen

15 total atoms

8. FeS2

2 Elements: Iron and Sulfur

1 Iron2 Sulfur

3 total atoms