Question

Find Mass Number and Number of Protons in an Element
An atom of an element x has 81 electrons and 24 neutrons? (a) How many protons does it have? (b) What is it mass number?

Answer 1

Hey!

•••> Atomic number ( X ) = 81 [ Atomic number is the number of electrons ( e- ) or protons ( p ) in an atom ]

•••> Mass number ( A ) = 81 + 24 [ Mass number is the total sum of protons and neutrons in an atom ]
Now,
a) Number of protons = 81
b) Mass number = 81 + 24 = 105

Answer 2

Answer:

Hey!

•••> Atomic number ( X ) = 81 [ Atomic number is the number of electrons ( e- ) or protons ( p ) in an atom ]

•••> Mass number ( A ) = 81 + 24 [ Mass number is the total sum of protons and neutrons in an atom ]

Now,

a) Number of protons = 81

b) Mass number = 81 + 24 = 105: