16.2 Masses of Atoms

The atomic mass of an element is _______ of that element.

• the average mass of all an elements isotopes

• the number of protons plus the number of neutrons of an atom

• the number of protons in each atom

• the number of electrons in each atom

The ___ of an element is the number of _______ of an atom of that element.

• atomic mass, electrons in the nucleus

• mass number, neutrons in the nucleus

• mass number, protons plus electrons in the energy levels

• atomic number, protons in the nucleus

The _______ of an atom is the number of neutrons plus protons.

• atomic number

• nucleus number

• mass number

• half-life

_______ are atoms of the same element that have different numbers of neutrons.

• Compounds

• Isotopes

• Alpha particles

• Beta particles

The atomic number of manganese is 25; its mass number is 55. How many neutrons does an atom of manganese have in its nucleus?

• 25

• 30

• 55

• 80

The mass of an electron is ______.

• negligible (so small, we don't count it)

• the mass of the neutrons plus the mass of the protons

• equal to the mass of a proton

• equal to the mass of the nucleus

The mass of proton is measured in ______.

• nanograms (ng)

• microns or micrometers (μm)

• atomic mass units (u)

• milligrams (mg)

One way of showing the differences between isotopes of an element is to put the _____________ after the name of the element. (Hyphen Notation)

• atomic number

• # of electrons

• mass number

• # of energy levels

An element has two naturally occurring isotopes. One is 10.013 amu and is 19.9% abundant. The other is 11.01 amu and is 80.1% abundant. What is the average atomic mass?

• 9.01u

• 12.01u

• 10.92u

• 10.81u

Chlorine has two naturally occurring isotopes, Cl-35 and Cl-37, The atomic mass of chlorine is 35.45. Which of these two isotopes of chlorine is more abundant?

• Cl-35

• Cl-37

• Cannot be determined from the information provided.

• Cl-36