Counting Atoms

Definitions

100

What is a coefficient? 

The regular sized numbers that tell how many molecules there are 

200

What is a Subscript? 

The smaller numbers that tell how many atoms there are. 

300

What is a compound?

A molecule made up of at least 2 or more different elements. (Ex. H₂O, CO₂, NaCl)

400

What is the Law of Conservation of Mass?

mass can neither be created nor destroyed

500

What is a chemical formula? 

A chemical formula is used to represent a molecule or a compound. It describes the type of atom and their numbers in the compound.

Counting Atoms #1

100

How many atoms are in this formula? 

3H₂O

9 

200

How many atoms are in this formula? 

Ba(OH)₂

5

300

How many atoms are in this formula? 

Ca₃(PO₄)₂

13

400

How many total atoms are in the following chemical formula?

Al₂(SO₄)₃

17 total atoms

500

How many oxygen atoms are on the product (right) side of the formula?

6H₂O + 6CO₂ → C₆H₁₂O₆ + 6O₂

18 atoms of Oxygen

Counting Atoms #2

100

How many atoms are in this formula? 

2 H₂O

6

200

How many atoms of sulfur are in this formula? 

3Na₂SO₄

3 total sulfur atoms

300

How many atoms are in this equation? 

 4Pb(NO₃)₂

36

400

How many total atoms are in the molecule below?

5(NH₄)₂O

55 atoms (10 Nitrogen, 40 Hydrogen, 5 Oxygen)

500

How many Oxygen atoms are on the product (right) side of the equation?

2C₂H₆ + O₂ → 4CO₂ + 6H₂O

14 oxygen atoms

Counting Atoms #3

100

How many atoms are in this formula? 

K₂CO₃

6

200

True or false: this equation = 100 atoms 

4 C₆H₁₂O₆           

FALSE

300

How many total atoms are in this molecule?

C₁₂H₂₂O₁₁

45 atoms

400

What is the total number of atoms in this formula?

 5Ca(OH)₂                            

25

500

How many atoms of phosphorous are in the molecule below?

6Ca₃(PO₄)₂

12 atoms

Chemistry Review

100

A ball has a mass of 10g and a volume of 20cm³. What is the density of the ball?

0.5 g/cm³

200

An element has high luster, is a good conductor of electricity, and exists as a solid at room temperature. Is it a metal, nonmetal, or metalloid?

Metal

300

An element is dull, brittle, and a semiconductor. Is it a metal, nonmetal, or metalloid?

Metalloid

400

A cube has a density of 0.27 g/mL. Cooking oil has a density of 0.91 g/mL. Will the cube float in cooking oil?

Yes - the density of the cube is less than the density of the oil (0.27 is less than 0.91)

500

This element is on the left side of the periodic table with the metals, but does not behave like a metal. What element is it?

Hydrogen (H)