Element Z forms a stable ion Z3– which has the electron configuration 2,8,8. To which Group and Period of the Periodic Table does Z belong?
Answer:
2) D
The ion has a charge of 3-, which means that it has gained 3 extra electrons. The ion’s electronic configuration (EC) is 2,8,8 and since we know that it has gained 3 electrons, we can deduce that the element Z has a normal EC of 2,8,5.
The number of electrons in the last shell (in this case, 5), show which group the element is in. Z is in group ‘5’. However, this is without considering the transitional elements in between group 2 and ‘3’. There are 10 groups of transitional elements. Therefore, we need to add 10 to 5. So Z is in the group: 10 + 5 = 15. Please refer to the periodic table below.
The number of shells shows which period it is in. EC of element Z is 2,8,5. First shell has 2 electrons, the second has 8 and the third has 5. We know Z has three shells. Therefore, Z is in period 3.
