Question

Isotopes have similar
A) Physical properties
B) Chemical properties
C) Mass number
D) Number of neutrons

Answer 1

Hint: Isotopes of an element share the same number of protons but have different numbers of neutrons. Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. The combined number of protons and neutrons is called nucleon number.

Complete step-by-step answer:
Isotopes are different atoms of the same element. They have the same atomic number, same number of protons and same number of electrons. But they have different numbers of neutrons and different atomic numbers. For example, consider two isotopes of chlorine. They are \[_{17}^{35}{\text{Cl}}\] and \[_{17}^{37}{\text{Cl}}\] .

In these two isotopes, the atomic number is the same. It is 17. The number of electrons is the same and is 17. The number of protons is also the same and is 17. But the mass number is different. The two isotopes \[_{17}^{35}{\text{Cl}}\] and \[_{17}^{37}{\text{Cl}}\] have the mass numbers 35 and 37 respectively. The two isotopes \[_{17}^{35}{\text{Cl}}\] and \[_{17}^{37}{\text{Cl}}\] have 18 and 20 neutrons respectively.

The physical properties of isotopes are different, due to the different number of neutrons present in the nucleus. So, option (A) is incorrect.

The number of protons and the number of neutrons determine an element's mass number: mass number = protons + neutrons, so it is obvious that mass no. will be different. Therefore, option (C) & (D) are incorrect.

The chemical properties of isotopes are similar, because we know that Isotopes of an element have the same number of electrons and protons and the chemical properties are decided by no. of electrons.

Hence the correct answer is option (B)

Note: Isobars are atoms or nuclides of separate chemical elements having the same number of nucleons. It is originally taken from the combination of two Greek words- isos means equal and bar means weight. Isotopes have different mass numbers whereas isobars have the same mass number. Students usually confuse isotopes and isobars. It’s a very common confusion. Keep in mind that Isotopes have the same atomic number whereas isobars have different atomic numbers.