Atomic Mass and Atomic Number

If the atomic mass is the number of protons and neutrons, and the atomic number is the number of protons, how

can the number of electrons be determined?

• By subtracting the number of protons by the number of neutrons.

• It is the same as the number of protons.

• By subtracting the number of protons from the atomic mass.

• By adding the protons and neutrons.

If the atomic number of Pb (Lead) is 82 and its atomic mass is 205, how many neutrons does it have?

• 123

• 82

• 205

• 287

Hydrogen has an atomic mass of 3 and atomic number of 1. How many protons and neutrons does hydrogen have?

• 3 protons and 1 neutron

• 1 proton and 2 neutrons

• 2 protons and 1 neutron

• 1 proton and 3 neutrons

Which element is the heaviest?

• Na

• Ar

• Ca

• O

Which atom has an atomic mass of 16?

• Na

• Ar

• Ca

• O

An atom has an atomic number of 11 and an atomic mass of 23. Which of the following statements is correct?

• It has 11 protons and 11 neutrons.

• It has 11 electrons and 12 protons.

• It has 11 protons and 11 electrons.

• It has 23 protons and 11 electrons.

Which of the following atoms has the greatest number of neutrons?

• 
• 
• 
• 

Which pair of particles contributes the most to the overall mass of the atom?

• Electrons and protons

• Protons and neutrons

• Electrons and neutrons