Counting Atoms in Chemical Formulas

Front

What is a chemical formula?

Back

A chemical formula is a way of expressing the composition of a substance using symbols for its constituent elements and numbers to indicate the quantity of each element.

Front

What does a subscript in a chemical formula indicate?

Back

A subscript indicates the number of atoms of the element in a molecule. For example, in H₂O, the '2' indicates there are two hydrogen atoms.

Front

What is a coefficient in a chemical formula?

Back

A coefficient is a number placed in front of a chemical formula to indicate how many molecules or moles of that substance are present. For example, in 2H₂O, the '2' indicates there are two molecules of water.

Front

How many total atoms are in the compound C₆H₁₂O₆?

Back

24 total atoms (6 Carbon + 12 Hydrogen + 6 Oxygen = 24).

Front

What is the formula for propane?

Back

C₃H₈.

Front

How many Sodium (Na) atoms are in 4NaCl?

Back

4.

Front

What is the formula for one carbon (C) and one oxygen (O)?

Back

CO.

Front

How many total atoms are in the compound H₂SO₄?

Back

7 total atoms (2 Hydrogen + 1 Sulfur + 4 Oxygen = 7).

Front

What is the formula for ethylene?

Back

C₂H₄.

Front

What does the formula CO₂ represent?

Back

Carbon dioxide, which consists of one carbon atom and two oxygen atoms.