Counting Atoms #1

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

How do you determine the number of elements in a chemical formula?

Back

Count the different element symbols present in the formula. For example, in NaHCO3, there are 4 different elements: Na, H, C, and O.

Front

What does the subscript in a chemical formula indicate?

Back

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

Front

What is the difference between an element and a compound?

Back

An element is a pure substance made of only one type of atom, while a compound is a substance formed when two or more different types of atoms bond together.

Front

How many sodium (Na) atoms are in the formula 6NaCl?

Back

There are 6 sodium (Na) atoms in the formula 6NaCl.

Front

What is the total number of atoms in the compound NaHCO3?

Back

There are 6 total atoms in NaHCO3: 1 Na, 1 H, 1 C, and 3 O.

Front

How many atoms of iron (Fe) are in the compound Fe2O3?

Back

There are 2 atoms of iron (Fe) in the compound Fe2O3.

Front

What is the chemical formula for table salt?

Back

The chemical formula for table salt is NaCl.

Front

How many oxygen (O) atoms are in the compound 3Fe2O3?

Back

There are 9 oxygen (O) atoms in the compound 3Fe2O3.

Front

What does the coefficient in a chemical formula represent?

Back

The coefficient represents the number of molecules or formula units of the compound. For example, in 3H2O, the '3' indicates there are 3 molecules of water.