4.3/4.4 How Atoms Differ/Radioactive Decay

Why are all atomic masses not nearly whole numbers?

• This is due to the mass of all the electrons in the atom.

• This is because of experimental error.

• This is because atomic masses are the weighted average of the masses of all naturally-occurring isotopes.

• This is due to binding energy of the atoms.

The atomic number of an element is defined by its number of ________.

• protons

• neutrons

• electrons

• nuclei

The sum of the protons and neutrons in a nucleus is __________.

• the atomic number

• the mass number

• Avogadro's number

• the element number

Which of the following is true for any atom?

• atomic number = number of protons = number of electrons

• atomic number = number of neutrons = number of electrons

• mass number = number of protons = number of electrons

• mass number = number of protons = number of neutrons

How is the atomic mass unit (amu) defined?

• 1/12 the mass of a carbon-12 atom

• 1/14 the mass of a nitrogen-14 atom

• 1/13 the mass of a carbon-13 atom

• 1/16 the mass of an oxygen-16 atom

How many neutrons in C-14?

• 6
• 7
• 14
• 8

Tags

NGSS.HS-PS1-8

How many protons does this isotope of titanium have?

• 48
• 22
• 26
• 70

Tags

NGSS.MS-PS1-1

How many neutrons does uranium-235 have?

• 238
• 92
• 146
• 143

Tags

NGSS.HS-PS1-8

What quantities vary between isotopes of an element?

• protons, electrons, and atomic mass
• protons, electrons, and atomic number
• neutrons and electrons
• neutrons and atomic mass

Tags

NGSS.HS-PS1-8

24.1% of all the isotopes of a an element have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu.

What is the atomic mass of this element?

• 74.92 amu

• 24.97 amu

• 75.01 amu

• 74.51 amu