Question

Can someone please explain how to do this.
Phosphorus3-
# of protons____
# of electrons= 18
# of neutrons____
atomic #____
Mass #=31
I have to find the missing numbers.

Answer 1

Look on a periodic table to get the number of protons.
In this case it would be 15. Next use your mass#-your #of protons to find the # of neutrons.

Answer 2

The atomic number is the number at the top of the element symbol.

Answer 3

Hope this helps.

Answer 4

How is that possible when you have the 3- ?

Answer 5

the 3- implies that you have 3 more electrons than it would usually have. Phosphorus originally has 15 electrons and 15 protons that cancel each other out. But since you have 18 electrons like you have stated, then the 3 extra electrons will make it p3-.

Answer 6

You still have the same number of protons. Because if the proton number went up to 18 as well as the electrons, then it wouldn't be considered 3- and it would actually be Argon. Only electrons can move but not the protons.

Answer 7

Okay so if you have for example vanadium^0 then would everything be the same as normal or would the electrons changed?

Answer 8

Yeah the electrons and the protons would be the same and cancel each other out. the only difference is the # of neutrons which you get by #Atomic mass-#of protons

Answer 9

Does this make sense?

Answer 10

okay thank you and one more question if you have an element with a 4+ how would you do those?

Answer 11

Oh the same way just backwards since it is a positive charge. Instead of adding electrons you would take away electrons. For example take Carbon that originally has 6 electrons. As Carbon 4+ it will have 2 electrons.

Answer 12

Okay. Thank you so much.

Answer 13

For sure.