Carbon-12 and carbon-14 are isotopes of each other. What is different about them?
ANumber of protons
BNumber of electrons
CNumber of neutrons
DTheir chemical symbol
Isotopes of the same element have the same number of protons (that is what makes them the same element) and the same number of electrons in a neutral atom. They differ only in the number of neutrons, which changes the mass but not the chemical identity.
Question 2 True / False
Most isotopes of an element are radioactive.
TTrue
FFalse
Answer: False
Most isotopes are stable and not radioactive at all. For example, carbon-12 and carbon-13 are both stable isotopes of carbon. Only certain isotopes (like carbon-14) are radioactive, meaning their nuclei are unstable and break down over time.
Question 3 Short Answer
An atom has 6 protons and 8 neutrons. What is its mass number?
Think about your answer, then reveal below.
Model answer: 14.
The mass number is the total number of protons plus neutrons in the nucleus. This atom has 6 protons + 8 neutrons = 14. Since it has 6 protons, it is a carbon atom, specifically carbon-14.