Final answer:
In Chemistry, the atomic number of an isotope is the number of protons (50 for tin) whereas the mass number is the total of protons and neutrons (118 for the specified tin isotope with 68 neutrons). Beta decay equations involve the conversion of a neutron to a proton and the emission of an electron, as shown for Tin-121 and Technetium-99. The average atomic mass of an element with multiple isotopes is calculated using the weighted average of the isotopic masses based on their abundances.
Step-by-step explanation:
The subject of your question is Chemistry, and it falls under the High School grade level. The atomic number of an isotope corresponds to the number of protons in the nucleus, while the mass number is the sum of protons and neutrons.
For the tin isotope in question, with 50 protons and 68 neutrons, the atomic number is 50, and the mass number is 118 (50 protons + 68 neutrons).
When considering the beta particle emission of Tin-121, the nuclear equation can be written as 121Sn -> 121Sb + e-, where Sn is tin and Sb is antimony, the daughter isotope. Similarly, for the beta particle emission of Technetium-99, the nuclear equation would be 99Tc -> 99Ru + e-, with Ruthenium (Ru) being the daughter isotope.
To calculate the average atomic mass of an element with multiple isotopes, you would use the isotopic masses and their respective abundances. For example, to calculate the average mass of a Mg atom with given abundances and mass values: (0.7870 × 23.98 amu) + (0.1013 × 24.99 amu) + (0.1117 × 25.98 amu). The result is the weighted average of the isotopic masses.