Question

1. why is the atomic mass of chlorine 35.45 amu instead of 35.00 amu? 4 points ave. atomic mass = \frac{(mass of isotope 1)(% abundance)+(mass of isotope 2)(% abundance)+(mass of isotope 3)(% abundance)}{100} a. presence of isotopes with different masses b. rounding error in periodic table c. chlorine gains electrons d. chlorine has extra protons 21. write the number of protons, neutrons, and electrons for cl - 37. 4 points a. 17 p, 20 n, 17 e b. 17 p, 20 n, 18 e c. 18 p, 19 n, 17 e d. 17 p, 37 n, 17 e

Explanation:

• For question 20: Chlorine has isotopes like Cl - 35 and Cl - 37. The atomic mass is the weighted - average of the masses of its isotopes based on their abundances. So the non - integer atomic mass is due to the presence of isotopes.
• For question 21: Chlorine has an atomic number of 17, so the number of protons (p) is 17. For Cl - 37, mass number = 37. Since mass number=protons + neutrons, neutrons (n)=37 - 17 = 20. In a neutral atom, number of electrons (e) = number of protons, so e = 17.

Answer:

1. A. Presence of isotopes with different masses
2. A. 17 p, 20 n, 17 e