Q39P - Chemistry: Molecular Nature Of Matter And Change

Question

Argon has three naturally occurring isotopes, ³⁶Ar, ³⁸Ar, and 
⁴⁰Ar. What is the mass number of each? How many protons, neutrons, and electrons are present in each?

Step-by-Step Solution

Answer

• The Mass number: ³⁶Ar(36), ³⁸Ar (38), ⁴⁰Ar(40)
• Number of protons: ³⁶Ar(18), ³⁸Ar (18), ⁴⁰Ar(18)
• Number of neutron: ³⁶Ar(18), ³⁸Ar (20), ⁴⁰Ar(22)
• Number of electrons: ³⁶Ar(18), ³⁸Ar (18), ⁴⁰Ar(18)

Step 1: Isotopes

The isotopes of an element are atoms that have different mass number but same atomic number.

Step 2: Number of protons, neutrons and electrons

Number of protons = Number of electrons = Atomic number

Number of neurons = Mass number - Atomic number

Isotopes	Mass number	Number of     protons	Number of      neutrons	Number of    electrons
36Ar	36	18	18	18
38Ar	38	18	20	18
40Ar	40	18	22	18