Problem: What are the numbers of electrons, sequentially, in each of the following ions?    Ca2+, Fe2+, I-, O2-       a) 20e-, 26e-, 53e-, 8e-b) 18e-, 26e-, 54e-, 8e-c) 22e-, 28e-, 52e-, 6e-d) 18e-, 24e-, 54e-, 10e-e) 20e-, 20e-, 53e-, 8e-

FREE Expert Solution

We’re being asked to determine number of electrons in the ions given.  Recall that the symbol for an element or ion is as follows:




  • The atomic number tells us the number of protons
  • Recall that in a neutral element the number of protons and electrons are equal
  • So we have to find the atomic number of each from the periodic table. 
  • But here we have ions so we have to modify it. 
    • Every (+) charge removes 1 electron. 
    • Every (-) charge adds 1 electron. 
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Problem Details

What are the numbers of electrons, sequentially, in each of the following ions?    

Ca2+, Fe2+, I-, O2-       

a) 20e-, 26e-, 53e-, 8e-

b) 18e-, 26e-, 54e-, 8e-

c) 22e-, 28e-, 52e-, 6e-

d) 18e-, 24e-, 54e-, 10e-

e) 20e-, 20e-, 53e-, 8e-

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Isotopes concept. You can view video lessons to learn Isotopes. Or if you need more Isotopes practice, you can also practice Isotopes practice problems.