Counting Atoms

What are the rules about symbols from the Periodic Table and how to write them?

• One Letter = Capitalized

  Two Letters = 1st Capital / 2nd Lowercase

• One Letter = lowercase

  Two Letters = 1st lowercase / 2nd Capital

What are these two elements?

• Potassium / Barium

• Potassium / Bismuth

• Potassium / Bromine

How many elements are in this formula? (Remember, a capital letters followed by a lowercase letter is ONE element)

• 3

• 4

• 5

• 2

What elements are present here?

• Sodium / Hydrogen / Carbon / Oxygen

• 
  

  Nickle / Hydrogen / Calcium / Oxygen

• 
  

  sodium hydrogen carbonate

What does this particular subscript tell us?

• There are 3 atoms of oxygen

• There are 3 molecules of oxygen

• 
  

  There are 3 total elements in the formula

True or False? The subscript applies to ALL of the atoms in the formula?

• True

• False

A coefficient of 2 will tell you that there are...

• 
  

  2 elements in the formula

• 2 molecules of the same formula

Let's count my long hand example.  Did it match what they multiplied?

Al Al (COOO) (COOO) (COOO)

Al = 2  C = 3  O = 9

• Yes

• NO

How many total nitrogen atoms are there?

• 2

• 4

• 6

• 8

How many total atoms are in 1 molecule of (NH₄)₂SO₄ ?

• 1

• 4

• 10

• 15