When a radioactive isotope decays by electron capture, the electron______ .
A) makes the parent isotope into an ion with a charge of negative one
B) combines with a proton in the nucleus; the atomic number of the daughter is one less than the parent
C) combines with a neutron in the nucleus, raising the mass number of the daughter isotope by one
D) makes the daughter isotope into an ion with a charge of positive one

Question

Quizplus · Accepted Answer

When a radioactive isotope decays by electron capture, the electron combines with a proton in the nucleus, decreasing the atomic number by one and forming a new element with a lower atomic number. This process does not affect the mass number, so the daughter isotope has the same mass as the parent. This is because electron capture reduces the number of protons in the nucleus by one, which changes the element, but the number of neutrons remains the same. Therefore, Choice B is the correct answer.

When a Radioactive Isotope Decays by Electron Capture, the Electron______