20.1.1 The Nature of Radioactivity Flashcards Preview

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Flashcards in 20.1.1 The Nature of Radioactivity Deck (12)
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1
Q

The Nature of Radioactivity

A
  • Nuclear chemistry is the study of the reactions of the nucleus.
  • Nuclear reactions involve various types of radioactivity.
2
Q

note

A
  • Nuclear chemistry is the study of the reactions of the nucleus.
  • In nuclear chemistry atoms can change from one element to another.
  • Nuclear reactions involve various types of radioactivity.
  • In the example of alpha (α) decay, an atom of uranium-238 ejects a helium nucleus (2 protons + 2 neutrons) becoming an atom of thorium-234 in the process. In nuclear reactions the atomic mass numbers
    of the reactants (238) and products (234 + 4) will be equal. The atomic number (or charge) of the reactants (92) will also equal the charge of the products (90 + 2).
  • In beta (β) decay, an electron is ejected by a nucleus. The electron is created as a product in the decay of a neutron to a proton. The creation of a proton changes the atomic number of the atom, thus changing it to the next element on the periodic table.
  • Gamma (γ) radiation is high-energy electro-magnetic
    radiation often emitted during nuclear reactions, but it is not particulate and therefore is not part of the balancing of equations.
  • In positron (β+) emission, a positively charged electron is ejected by a nucleus. The positron is created as a product in the decay of a proton to a neutron. The loss of a proton changes the atomic number of the atom, thus changing it to the previous element on the periodic table. A positron is an example of an antiparticle and it will interact with an electron creating a burst of gamma radiation.
  • In electron capture, an electron is captured by a nucleus when a proton changes to a neutron.
3
Q

Which of the following statements about nuclear emission is not correct?

A

Electrons are never involved in nuclear reactions.

4
Q

The reaction 14 6 C -> 14 7 N + 0 -1 e is an example of a beta-decay reaction.
Which of the following statements about a beta decay reaction is not correct?

A

The electron comes from the innermost, core electron orbital (an s orbital) just outside of the nucleus.

5
Q

Let’s examine a beta emission reaction.

231 90 Th -> 231 91 Pa + 0 -1 e

Which of the following statements about this event is not correct?

A

The electron has a mass of 1 and a charge of 0.

6
Q

What is the missing particle, P, that is necessary to balance the following nuclear reaction?
238 92 U -> 234 90 Th = (

A

4 2 He

7
Q

Look at the following beta decay reaction for potassium 40

40 19 K -> 0 -1 e + 40 20 Ca

Which of the following statements about this event is not correct?

A

A proton has a significantly greater mass than a neutron.

8
Q

Look at the alpha (α) particle emission.

216 84 Po -> 212 82 Pb + 4 2 He

Which of the following statements about this reaction is not correct?

A

Although Po and Pb have the same mass number, they are different elements because they have different atomic numbers.

9
Q

Which of the following statements about nuclear chemistry symbols and equations is not correct?

A

The mass number is equal to the total number of protons in the element or particle.

10
Q

Which of the following nuclear reactions is not correctly balanced?

A

59 26 Fe -> 59 27 Co + 4 2 He

11
Q

Which of the following statements about an alpha emission reaction is not correct?

A

The daughter element in an α emission reaction is found in the periodic table by moving two positions to the right of the parent element in the table.

12
Q

Which of the following statements about nuclear reactions is not correct?

A

The particle 0 +1 e is referred to as anti-matter. It has a slightly greater mass than an electron, 0 -1 e, because of the positive charge

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