Part A Technetium-99m has a half-life of 6.0 hours. Assume you started with 28 mg of technetium-99m and 24 hours have passed, which is equivalent to 4 half-lives. How much technetium-99m remains?

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

the answer for sodium is 0.186

the answer for rubidium is 0.251

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.