Atomic Structure 1

All atoms of the same element have the same:

• Number of protons

• Number of neutrons

• Mass number

• Mass

The sum of the protons and neutrons in an atom equals the

• Atomic number

• Number of electrons

• Atomic mass

• Mass number

Which of these statements is false?

• Electrons have a negative charge

• Electrons have a mass of 1amu

• The nucleus of an atom is positively charged

• The neutron is found in the nucleus of an atom

An atom of an element with atomic number 48 and mass number 120 contains

• 48 protons, 48 electrons, and 72 neutrons

• 72 protons, 48 electrons, and 48 neutrons

• 120 protons, 48 electrons, and 72 neutrons

• 72 protons, 72 electrons, and 48 neutrons

Relative atomic masses are measured in

• nanograms

• angstroms

• grams

• amu

Complete the following:

1. Atomic number = 9
2. Number of neutrons = 10
3. Mass number = ?
4. Number of protons = ?
5. Number of electrons = ?

Complete the following:

1. Mass number = 14
2. Number of neutrons = 7
3. Atomic number = ?
4. Number of protons = ?
5. Number of electrons = ?

1. Rubidium is a soft, silvery-white metal that has two common isotopes, Rb-85 and Rb-87. If the abundance of Rb-85 is 72.2% and the abundance of Rb-87 is 27.8%, what is the average atomic mass of rubidium?

Explain why is an atom considered to be neutral.

Where is most of the mass located in an atom?