CHEMISTRY - Matter - Atomic Number & Mass Number

The video tutorial explains the concepts of atomic and mass numbers in elements. The atomic number, denoted by Z, represents the number of protons in an atom and is unique to each element. The mass number, denoted by A, is the sum of protons and neutrons in an atom. The tutorial demonstrates how to calculate the number of neutrons by subtracting the atomic number from the mass number, using examples of elements like oxygen and lithium.

What does the atomic number of an element indicate?

• The sum of protons and neutrons

• The total number of electrons

• The number of protons in an atom

• The number of neutrons in an atom

Which element has an atomic number of 8?

• Oxygen

• Nitrogen

• Carbon

• Hydrogen

What does the mass number of an element represent?

• The number of protons only

• The number of neutrons only

• The sum of protons and neutrons

• The number of electrons

How do you calculate the number of neutrons in an atom?

• Divide the mass number by the atomic number

• Add the atomic number to the mass number

• Subtract the atomic number from the mass number

• Multiply the atomic number by the mass number

If lithium has a mass number of 7 and 3 protons, how many neutrons does it have?

• 6

• 5

• 4

• 3