Chemical Formulas and Atom Counting

This video tutorial teaches how to count atoms in chemical formulas. It starts with ammonium (NH4), explaining that nitrogen has one atom and hydrogen has four, totaling five atoms. The second example is copper II phosphate (Cu3(PO4)2), where the subscript outside the parentheses is distributed to elements inside, resulting in three copper, two phosphorus, and eight oxygen atoms, totaling 13 atoms.

What does the subscript '4' in NH4 indicate?

• The number of nitrogen atoms

• The number of molecules

• The number of hydrogen atoms

• The total number of atoms

If an element in a chemical formula has no subscript, what number is assumed?

• Three

• Zero

• Two

• One

How many total atoms are present in NH4?

• Seven

• Six

• Five

• Four

What is the chemical formula for copper (II) phosphate?

• Cu(PO4)3

• Cu2(PO3)4

• Cu3(PO4)2

• Cu3(PO3)2

When a subscript is outside parentheses, what should you do?

• Divide it among the elements inside

• Multiply it with the elements inside

• Add it to the elements inside

• Ignore it

How many copper atoms are in Cu3(PO4)2?

• One

• Two

• Three

• Four

How many phosphorus atoms are in Cu3(PO4)2?

• Two

• Three

• Four

• Five

How many oxygen atoms are in Cu3(PO4)2?

• Seven

• Six

• Eight

• Nine

What is the total number of atoms in Cu3(PO4)2?

• Thirteen

• Ten

• Eleven

• Twelve

Which element in Cu3(PO4)2 has the highest number of atoms?

• Phosphorus

• Hydrogen

• Oxygen

• Copper