O Level Chemistry: Isotopes

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It is important that O-Level Chemistry students understand the concepts about Isotopes in order to answer application questions related to it.

Isotopes are atoms of the same element with the same number of protons but different number of neutrons.

This mean that for isotopes, the number of protons and electrons will be the same but the mass (nucleon) number will be different.

Take chlorine as an example. 75% of naturally chlorine atoms are Cl-35 and the remaining being Cl-37. By simple math, you should get the average atomic mass (A_r) of chlorine to be 35.5 as shown in most Periodic Table.

Click HERE for more in-depth discussions on Isotopes in the topic of Atomic Structure.

Most elements in the periodic table have isotopes, and many of these isotopes are radioactive. Some of the common uses of radioactive isotopes are in medical & chemical industry. Clean energy industry such as the Nuclear Plants are making use of the radioactive isotopes to produce large amount of energy in several countries, much to the disapproval by groups that are aware of the danger in radioactive substance.

Let’s take a look at a very common exam-based Multiple Choice Question (MCQ).

Quick Check 1:

Isotopes are

A)  atoms of the same element with different masses

B)  atoms of different elements with different masses

C)  atoms of different elements with the same mass

D)  atoms of the same element with same mass

Based on our discussion, we should arrived at answer A with two sets of keywords “atoms of the same element” and “different masses”.

Now, try out the following MCQ question on your own:

Quick Check 2:

Which of the following statements concerning the two isotopes 146C and 147N is/are correct?

1. Both isotopes have the same chemical properties

2. Both isotopes contain 14 nucleons per atom

3. The carbon isotope has more neutrons per atom than the nitrogen isotope

A)  1, 2 and 3 are correct

B) 1 and 2 only are correct

C) 2 and 3 only are correct

D) 3 only is correct

Go try it out and leave your thoughts/answers in the comment section below. Do participate in the discussions to help each other to master Chemistry.

PS: If you find this post on Isotopes useful to any of your friends, feel free to forward to them. =) Keep sharing!

Related Articles:

• O Level Chemistry – Isotopes
• O Level Chemistry – Atomic Structure
• O Levels Chemistry Tips Blog Marathon – Day 4
• O Level Chemistry: Difference between Atom, Molecule & Particle
• O Level Chemistry – Periodic Table Mini Series (Part II)