Number of Subatomic Particles in an Atom

Number of Subatomic Particles in an Atom

by Mrs. Sanner

​Number of Protons

• ​To determine the number of protons an atom has, you simply look at the atomic number.

​Number of Electrons

• ​To find the number of electrons, you have to remember that the number of electrons = the number of protons. So, you look at the atomic number for number of protons, and number of electrons is the same.

​Number of Neutrons

• ​To find the number of neutrons an atom has, you must first round the atomic mass to a whole number.

• ​Then you take rounded atomic mass minus atomic number.

• ​Rounded mass - atomic number = number of neutrons

Multiple Choice

How many protons does Mercury (Hg) have?

• 80

• 201

• 121

• 200.59

Multiple Choice

How many electrons does Silver have?

• 61

• 47

• 107

• 108

Multiple Choice

How many neutrons does Copper have?

• 64

• 29

• 35

• 34