Counting Atoms

Counting Atoms

Unit 5 Section 1

Coefficient vs Subscript

• Coefficient: Numbers in front of a formula which gives the total number of compounds.

• Subscripts: The small number to the bottom right of an element, which tells the number of atoms of the element immediately before it.

Multiple Choice

What is the Coefficient?

• 4

• 3

• 1

• 0

Multiple Choice

What is the subscript of Nitrogen?

• 4

• 3

• 1

• 0

Counting Atoms

• The Coefficient should be multiplied by the subscript of each element.

• The Coefficient is applied to all the elements in the compound behind the coefficient

• The subscript can only be applied to the element directly in front of it.

• * Remember if there is no number written in the subscript position it is counted as 1 atom*

Multiple Choice

How many Carbon are in the compound?

• 4

• 5

• 20

• 9

Multiple Choice

How many Bromine atoms are there in the compound?

• 4

• 7

• 12

• 6

Multiple Choice

How many Phosphorous atoms are there in the compound?

• 2

• 3

• 5

• 6

Counting Atoms: Formulas with parenthesis

• The subscript on the outside of the parenthesis applies to everything within the parenthesis.

• Multiple any subscript on the inside of the parenthesis by the subscript outside the parenthesis

• multiply all numbers by the coefficient for a total number of atoms

Multiple Choice

How many Hydrogen atoms are in the molecule?

• 3

• 4

• 12

• 1

Multiple Choice

How many Strontium atoms are in the compound?

• 6

• 2

• 3

• 5

Multiple Choice

How many atoms of oxygen are in the compound?

• 3

• 4

• 1

• 12

Multiple Choice

How many Phosphorous atoms are in the molecule?

• 2

• 4

• 1

• 8

Multiple Choice

How many Oxygen atoms are in the compound?

• 8

• 4

• 16

• 6