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 provides examples using hydrogen, oxygen, and lithium to illustrate how to calculate the number of neutrons by subtracting the atomic number from the mass number. The video emphasizes the importance of understanding these numbers for identifying and differentiating elements.

What does the atomic number of an element indicate?

• The number of neutrons in an atom

• The total number of electrons in an atom

• The number of protons in an atom

• The sum of protons and neutrons in an atom

Which element has an atomic number of 8?

• Oxygen

• Hydrogen

• Nitrogen

• Carbon

What does the mass number of an element represent?

• The number of electrons in an atom

• The number of protons in an atom

• The number of neutrons in an atom

• The sum of protons and neutrons in an atom

How many neutrons are present in an oxygen atom with a mass number of 16?

• 12

• 10

• 8

• 6

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

• 2

• 5

• 3

• 4