General Chemistry Question

Question

6. Identify for an atom of 96Mo: element name: _____________

Z, atomic number = ____ A, mass number = ____ number of neutrons = ____ total “+” charge in the nucleus = ____ total number of subatomic particles = ___

7. Use the isotope data to calculate the relative atomic mass of Si, to 8 s.f. = _____________

Isotope m/amu % Abundance

28Si 27.97692653 92.22 %

29Si 28.97649470 find: _____

30Si 29.97377017 3.09 %

Answer 1

6.) Element name = molybdenum

atomic number = 42

mass number = 96

number of neutrons = 96 - 42 = 54 neutrons

total + charge in nucleus = 42

total number of subatomic particles = 42 protons + 42 electrons + 54 neutrons = 138

7). You could simply add 92.22% + 3.09% to get 95.31% and take that from 100% to get 4.69% for 29Si, but to do it the correct way, see below...

(0.9222 * 27.97692653) + (x * 28.97649470) + (0.0309 * 29.97377017) = 28.0855

25.8003216 + 28.9764947x + 0.9261895 = 28.0855

x = 0.046899699 x100% = 4.6899699 = 4.6899700 % (8 sig. figs. is ridiculous since the % of 30Si is given to only 3 sig.figs. and the others to 4 sig.figs. and the periodic table value is given to only 6 sig.figs.)