Fill in the sentences below that describe the principles of radioactive decay and radiometric dating. Let’s review the three radioactive decay...

Fill in the sentences below that describe the principles of radioactive decay and radiometric dating.

Let’s review the three radioactive decay processes:

• Alpha particle emission: Two protons and two neutrons are emitted from the nucleus, resulting in a lower mass number by -4 and a lower atomic number by -2 for the isotope.
• Beta particle emission: A neutron is actually a combination of a proton and an electron, and in this process an electron from the neutron is emitted from the nucleus. This doesn’t affect the mass number, but it does result in the gain of one more proton and thus changes the atomic number by +1.
• Electron capture: When an electron is added to the nucleus, it is attracted to the positive charge of a proton. Together, they cancel each other out to result in a neutron. This additional neutron in the nucleus results in one less proton, thus affecting the atomic number by -1.

Match the words in the left column to the appropriate blanks in the sentences on the right. Note that some terms will remain unused and some may be used more than once.

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• 3
• 7
• proton
• neutron
• mass number
• atomic number

• 1. During electron capture, the   remains unchanged.
• 2. In electron capture, when an electron and a proton combine to form an additional neutron, the nucleus will now contain one less  . This affects the   by a decrease of -1.
• 3. In beta particle emission, the nucleus will end up containing one more  .
• 4. If 1:7 is the ratio of radioactive parent atoms to stable daughter atoms, there is one parent for every   daughter atoms and   half-lives have passed.