Isotopes and Average Atomic Mass

An isotope has three forms.  30% have a mass of 4 amu, 20% have a mass of 5 amu and 50% have a mass of 3 amu.  Average atomic mass will be closest to

• 2 amu
• 3 amu
• 4 amu
• 5 amu

Calculate the average atomic mass of silver.

• 106.38649amu
• 111.91896amu
• 107.8677amu
• 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?

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

Compute the average atomic mass for silicon:

• 27.977
• 28.09
• 28.976
• The average mass cannot be determined from provided information.

Oxygen has 8 protons. What is oxygen's atomic number?

• 16
• 8
• 15.999
• 0

A neutral atom of Carbon-13 has ________ electrons and _________ neutrons

• 13, 13
• 6, 7
• 7, 7
• 6, 6

Isotopes are atoms of the same element that have the same number of __________ but different number of __________ . Therefore, isotopes of the same element have different masses. 

• protons, neutrons
• protons, electrons
• neutrons, protons
• electrons, protons

The  mass of an atom is located  in the ___________ and the volume of an atom is made of the ____________

• electron cloud, nucleus
• electron cloud, energy levels
• nucleus, electron cloud
• nucleus, neutrons

Do the following atoms belong to the same element? Explain
       Aluminum-27
       An atom with 14 protons and 13 neutrons

• Yes because they have the same number of protons
• Yes because they have the same mass
• No because they have different number of protons
• No because they have different number of neutrons

What is the atomic number of Neon, Ne?

• 10
• 20.1798
• 10.1798
• 7