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specific charge

Ok I now that when Cu 63 29 loses 2 electrons that it gains 2 protons, but why is the charge worked out like this 2x1.6x10^19 and not 31x1.6x10^19. Also why is the mass not work out by 65x1.67x10^-21 and why is it 65x1.67x10^-21. Surely when there is 2 more protons the nucleon gets bigger.
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Avatar for mik1a
mik1a
10
Original post by kiwi111
Ok I now that when Cu 63 29 loses 2 electrons that it gains 2 protons,


You lost me here. How does Cu 29 gain two protons? What process are you describing?
Original post by kiwi111
Ok I now that when Cu 63 29 loses 2 electrons that it gains 2 protons, but why is the charge worked out like this 2x1.6x10^19 and not 31x1.6x10^19. Also why is the mass not work out by 65x1.67x10^-21 and why is it 65x1.67x10^-21. Surely when there is 2 more protons the nucleon gets bigger.


When an atom loses electrons, it becomes a positive ion. It just means there are more positive charges than negative charges - there is a net charge. It does not mean it gains protons.

When copper-65 loses 2 electrons, it has a net positive charge of +2e which worked out be 2×1.60×10−19 2 \times 1.60 \times 10^{-19} C. It is usually the net charges that we are concerned in most of the problems not the total charges.
Original post by kiwi111
Ok I now that when Cu 63 29 loses 2 electrons that it gains 2 protons, but why is the charge worked out like this 2x1.6x10^19 and not 31x1.6x10^19. Also why is the mass not work out by 65x1.67x10^-21 and why is it 65x1.67x10^-21. Surely when there is 2 more protons the nucleon gets bigger.


Hello there,

I struggle to understand what your query is but if I understand you, you are wondering why an atom of Cu-63 has a charge of 3.2×10−19C 3.2 \times 10^{-19} C as opposed to 4.96×10−18C4.96 \times 10^{-18} C and why its mass is 8.85×10−20kg 8.85 \times 10^{-20} kg as opposed to 1.09×10−19kg 1.09 \times 10^{-19} kg.

Firstly, the atom does not gain two protons. This would be the case if this process happened by beta decay, however Cu-63 is a stable atom (https://en.wikipedia.org/wiki/Isotopes_of_copper) and thus does not do this. The atom therefore has basically just lost two electrons, becoming an ion (this may happen during a chemical reaction for example). As electrons are of a negligible mass, the mass of this ion is the mass of the nucleus. The nucleon number has remained unchanged and thus the mass m=63(1.67×10−21)=8.85×10−20kg m = 63(1.67 \times 10^{-21}) = 8.85 \times 10^{-20} kg . Before the ionisation, the charge of Cu-63 was 0 0 . Therefore, the charge on the ion plus the charge of the two missing electrons must be 0 0 . This implies that the ion charge Q=2(1.6×10−19)=3.2×10−19C Q = 2(1.6 \times 10^{-19}) = 3.2 \times 10^{-19} C .

Again, I may not have understood your query so please do not hesitate to ask for further information. I hope that this has been helpful.

Smithenator5000.
Reply 4
Avatar for kiwi111
kiwi111
OP
5
Yeah im so sorry, in my book I have a question which states : Cu 63 29 loses two electrons. For the ion formed and then it asks for a charge and a specific charge so I got mixed up. Thank you for taking the time to answer my question :smile:
Original post by kiwi111
Yeah im so sorry, in my book I have a question which states : Cu 63 29 loses two electrons. For the ion formed and then it asks for a charge and a specific charge so I got mixed up. Thank you for taking the time to answer my question :smile:


I don't know who that was addressed to but you're very welcome. :smile:

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