Question

The table below shows the number of sub-atomic particles in an atom of magnesium. Sub-atomic Particles Sub-atomic Particle

Protons 12
Neutrons 12
Electrons 12
What is the amu of a magnesium atom?
A: 0
B: 12
C:24
D:36

Answer 1

24, because to get the AMU of an element you just add the number of protons and neutrons, because of the fact that electrons weight next to nothing.

Answer 2

Answer: The mass number of magnesium atom is 24 amu.

Step-by-step explanation:

Atomic number is defined as the number of protons or electrons that are present in a neutral atom.

Atomic number = number of protons = number of electrons

Mass number is defined as the sum of number of protons and neutrons that are present in an atom. It is expressed in 'amu'

Mass number = Number of protons + Number of neutrons

For the given element, "magnesium"

Number of protons = 12

Number of neutrons = 12

Number of electrons = 12

Mass number = 12 + 12 = 24

Hence, the mass number of magnesium atom is 24 amu.