Page 126 - Science Course 3 (Book 2)

Mo11-L3: Vocabulary Review

Direction: On each line, write the term from the word bank that correctly replaces the underlined words
in each sentence. NOTE: You may need to change a term to its plural form.

absolute age half-life isotope mineral radioactive decay

1. Salt is a(n) naturally occurring, inorganic solid with a def nite chemical
composition and an orderly arrangement of atoms.

2. My friend’s youngest sibling is a toddler. Her age in numbers is three years.

3. C-12 and C-14 are atoms with different numbers of neutrons, but both are made
of carbon.
4. For uranium-235, the length of time after which half of the parent isotopes decay
is 704 million years.

5. Elements that are used to determine the absolute age of rocks are those
elements that undergo a process in which atoms of the element change into
atoms of another element that is stable.

Mo11-L3: Key Concept Organizer

Direction: On each line, write the term from the word bank that correctly completes each sentence.
Each term is used only once.

atoms constant daughter energy half-lives normal

one-half parent radioactive radioactive decay rates stable

1. Most isotopes are .

2. Under conditions, isotopes do not change.

3. Unstable isotopes are known as isotopes.

4. Unstable isotopes release when they break down and form new stable
.

5. The process by which an unstable element changes into another element that is stable is called
.

6. Radioactive isotopes decay at different .

7. For every given isotope, the rate of decay is .

8. Rate of decay is measured in .

9. Half-life for an isotope occurs when half of the parent isotopes have become isotopes.

10. By two half-lives, 25 percent of the isotopes are isotopes.

11. By three half-lives, parent isotopes have changed to daughter isotopes by another .

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