Counting Atoms

Front

What is an atom?

Back

An atom is the smallest unit of matter that retains the properties of an element.

Front

What is a coefficient in a chemical equation?

Back

A coefficient is a number placed in front of a chemical formula to indicate how many molecules or atoms of that substance are present.

Front

How do you count the number of atoms in a chemical formula?

Back

To count the number of atoms, add the number of atoms of each element, considering coefficients and subscripts.

Front

What does a subscript indicate in a chemical formula?

Back

A subscript indicates the number of atoms of the element in a molecule.

Front

In the formula 2H2O, how many total atoms are there?

Back

There are 6 total atoms (2 Hydrogen + 1 Oxygen = 3 atoms per molecule, multiplied by 2 gives 6).

Front

What is the total number of atoms in the formula 3BeH5Si8?

Back

There are 16 total atoms (3 Beryllium + 5 Hydrogen + 8 Silicon = 16).

Front

How many atoms of Chlorine are in the formula 5Cl2?

Back

There are 10 atoms of Chlorine (5 x 2 = 10).

Front

What is the total number of atoms in the formula 2(H2)3?

Back

There are 12 total atoms (2 x 6 = 12).

Front

How many atoms of Iron are in the formula 2HFe5Cl?

Back

There are 10 atoms of Iron (2 x 5 = 10).

Front

What is the significance of parentheses in a chemical formula?

Back

Parentheses indicate that the enclosed elements and their subscripts are multiplied by the coefficient outside the parentheses.