About chemistry...?

Question

1. A certain atom has an atomic number of 15 and a mass number of 16. What is its electron configuration?

2. The element gallium exists in two isotopic forms with the following abundances: 60.16% Ga-19 and 39.84% Ga-17. Calculate the atomic mass of gallium.

Thanks in advance... God bless...

Answer 1

1. The neutral atom will be 1s2 2s2 2p6 3s2 3p3, because with 15 protons, it's phosphorus. (It's also very unlikely to see phosphorus with only one neutron, as the common form of phosphorus is P-31).

2. It's impossible to have gallium-17 and gallium-19, as gallium has 31 protons, but to calculate the atomic mass, you use the weighted average of the individual isotopes. So, given the numbers you have, and assuming (which is not a correct assumption) that the weights are exactly 17 and 19, the the atomic mass would be:

0.6016 * 19 + 0.3984 * 17 = 18.2032

Answer 2

1.atomic numer = proton number
proton number and electron number are equal
thus 15 proton = 15 electron
electronic configuration = 2,8,5
2.atomic mass = 60.16/100 multiply 19 + 39.84/100 multiply 17
thus atomic mass =18.2

Answer 3

atom with at.no.15 its EC- 2,8,5

Answer 4

1) [Ne]3s2 3p3

2) 18.20