atoms and elements

An atom is a . . .

• building block of life.

• basic unit of matter.

An element is a pure substance that is made from only one type of ______.

• compound

• atom

• molecule

There are approximately ___ known elements. These are all listed in the periodic table.

• 100

• 500

• 1,000

Atoms consist of three different types of subatomic particles called protons, neutrons and __________.

The _______ of an atom contains protons and neutrons.

The electrons of an atom are held in . . .

• a nucleus in the central region of the atom.

• shells surrounding the nucleus.

An electron has a ________relative mass.

An electron has a relative charge of ___.

• +1

• 0

• -1

A proton has a relative mass of ___.

A proton has a relative charge of ___.

• +1

• 0

• -1