A couple of Chemistery questions for the experts.?

Question

1. How do you find the number of protons, nuetrons and electrons in an isotope? If someone could show me a formula I am sure I could figure it out.
Specifically 207Pb, 16O(o not zero), 40K, 137Cs, and 40Ar? (numbers should be superscript)

2. How do you find the number of electrons in a specific element? Aluminum and Mercury would be great examples.

Thank you in advance, I have not taken a science class in about 15 years and it is like reading greek to me.

Answer 1

Protons = atomic number = top number on a periodic table block. Example: Pb's atomic number is 82 ~> 82 protons in Pb

Neutrons = Atomic Mass - Atomic number. in 207Pb, 207-82 = 125 neutrons

electrons = protons - charge. Since none of your examples have a charge, electrons = protons = atomic number again.

2. Electrons for any neutral element is equal to the number of protons. Example: Atomic number for Al is 13 ~> 13 electrons for the neutral atom.

Answer 2

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