The Nature of Radioactivity
- Nuclear chemistry is the study of the reactions of the nucleus.
- Nuclear reactions involve various types of radioactivity.
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- 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.
Which of the following statements about nuclear emission is not correct?
Electrons are never involved in nuclear reactions.
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?
The electron comes from the innermost, core electron orbital (an s orbital) just outside of the nucleus.
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?
The electron has a mass of 1 and a charge of 0.
What is the missing particle, P, that is necessary to balance the following nuclear reaction?
238 92 U -> 234 90 Th = (
4 2 He
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 proton has a significantly greater mass than a neutron.
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?
Although Po and Pb have the same mass number, they are different elements because they have different atomic numbers.
Which of the following statements about nuclear chemistry symbols and equations is not correct?
The mass number is equal to the total number of protons in the element or particle.
Which of the following nuclear reactions is not correctly balanced?
59 26 Fe -> 59 27 Co + 4 2 He
Which of the following statements about an alpha emission reaction is not correct?
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.
Which of the following statements about nuclear reactions is not correct?
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