AP 1.2 Mass Spectroscopy of Elements

Four isotopes of lead include lead-204, lead-206, lead-207, and lead-208. The average atomic mass of lead is 207.2. Which isotope of lead is likely to be the most abundant.

• 206
• 208
• 207
• 204

Calculate the average atomic mass of silver. Silver-107 106.90509amu 51.86% Silver-109 108.90470amu remaining%

• 111.91896amu
• 107.8677amu
• 106.38649amu
• 121

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? What element is it?

• 6.941, Lithium
• 10.812, Boron
• 9.012, Beryllium
• 12.011, Carbon

Which of following is not true of the carbon-14 atom?

• It has six electrons
• It has six protons
• It is the less common than carbon-12
• It has eight neutrons
• It has an average mass of 12.011 amu.

The element hafnium (Hf) has five stable isotopes. The correct number of nuclear particles in an atom of hafnium-178 is:

• 106 protons, 72 neutrons
• 72 protons, 72 electrons
• 72 protons, 178 neutrons
• 72 protons, 106 neutrons
• 72 protons, 106 neutrons, 72 electrons

The average mass of a magnesium atom is 24.31. If you were able to select and measure a single atom of magnesium, the chance that you would select an atom of mass 24.31 is about:

• greater than 50%
• 0.31%
• 24.31%
• 100%
• 0%

The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes. Rhenium-185 has in its nucleus

• 75 protons, 75 neutrons.
• 75 protons, 130 neutrons.
• 130 protons, 75 neutrons.
• 75 protons, 110 neutrons.
• not enough information is given.

Uranium occurs naturally as a mixture of uranium-235 and uranium-238. An atom of uranium-235 contains:

• 92 protons, 92 neutrons, 92 electrons
• 92 protons, 143 neutrons, 92 electrons
• 143 protons, 92 neutrons, 143 electrons
• 143 protons, 92 electrons, 92 neutrons
• none of these combinations

Which of the following statements are true of uranium-238? 1-Its chemical properties will be exactly like those of uranium-235 2-Its mass will be slightly different from that of an atom of uranium-235. 3-It will contain a different number of protons than an atom of uranium-235. 4-It is more plentiful in nature than uranium-235.

• 3, 4
• 1, 2, 3
• 1, 2, 4
• 2, 3, 4
• all of them

An isotope, X, of a particular element has an atomic number of 7 and a mass number of 15. Therefore,

• X is an isotope of nitrogen.
• X has 8 neutrons per atom.
• X has an atomic weight of 14.0067.
• a and b.
• a, b, and c.