Exploring Atomic Number, Mass Number, and Isotopes

Dr. Kent explains the concepts of atomic number, mass number, and isotopes. The atomic number, or Z, is the number of protons in an element's nucleus, defining its identity. Changing the number of protons transmutes the element. The mass number is the sum of protons and neutrons, differing from atomic mass. Atomic notation is used to specify these numbers. Isotopes have the same atomic number but different mass numbers due to varying neutrons. Examples include hydrogen isotopes. The video also covers calculating neutrons and understanding neutral atoms, concluding with further learning resources.

What is the atomic number of an element?

• The total number of protons and neutrons

• The number of protons in the nucleus

• The number of neutrons in the nucleus

• The average mass of the element

If an element has 16 protons, what is its atomic number?

• 16.01

• 8

• 16

• 32

Tags

NGSS.MS-PS1-1

What does the mass number of an element represent?

• The number of neutrons

• The number of protons

• The average mass of the element

• The total number of protons and neutrons

Which of the following is true about the mass number?

• It is the same as the atomic mass

• It represents the number of electrons

• It can be a decimal

• It is always a whole number

In atomic notation, what does the subscript represent?

• Mass number

• Atomic number

• Number of neutrons

• Number of electrons

How many neutrons are in an isotope of silicon with a mass number of 29?

• 15

• 29

• 43

• 14

Which isotope of hydrogen has one neutron?

• Hydrogen-2

• Hydrogen-1

• Hydrogen-4

• Hydrogen-3

What is the mass number of an isotope of cobalt with 27 protons and 33 neutrons?

• 33

• 27

• 61

• 60

How many electrons does a neutral neon atom have?

• 14

• 12

• 10

• 8

Tags

NGSS.MS-PS1-1

If a sodium atom has 11 protons and 10 electrons, what is its charge?

• Neutral

• Positive

• Cannot be determined

• Negative