Question

In the adjoining figure, the circles with the + sign represent protons and the empty circles represent neutrons. Determine which atoms in the figure are isotopes of each other.
A. 1 and 2

B. 1 and 3

C. 2 and 3

D. 1, 2, and 3

Answer 1

The atoms in the figure that are isotopes of each other are 2 and 3.

Answer 2

Answer: option C. 2 and 3.

Explanation:

1) Isotopes are atoms of a same element with different number of neutrons. That means that the isotopes of a same element have the same number of protons, since the number of protons is what identify an element.

2) For example, all the atoms of oxygen have 8 protons. But isotope oxygen-16 has 8 neutrons, while oxygen-18 has 10 neutrons.

3) In the figure there are 3 different atoms:

i) atom # 1 has 5 protons and 7 neutrons

ii) atom # 2 has 6 protons and 7 neutrons

iii) atom # 3 has 6 protons and 8 neutrons.

4) Hence the atoms with the same number of protons and different number of neutrons are the #2 and the # 3. So, they are the isotopes of the same element.