SOME CHEM QUESTIONS

[Hielly]

15. The electron configuration of an atom X is
1). Which of the following formulae is
most likely to be a compound formed with X?
A XF2
B CaX
C XCl3
D MgX2

2)Write the electron configuration of each of the
following in their ground states:
(a)copper atom
(b) calcium ion
(c) chloride ion.

<-- usethis but i got the end one wrong for (a)
not sure if ion means to minus 1 electron or plus

thanks!

[pHysiX]

calcium ion is Ca2+ n chloride ion is Cl-

[Hielly]

um so what would you write as the electron config

[pHysiX]

i'm at school right now but i'll try my best to help.

anyway, for calcium ion, we know there will be 18 electrons and for chloride ion, there will be 16 electrons. Copper is 29 electrons.

so, using the diagram/order u gave, fill the shells up. i'll come up with an answer later. hope it helps

EDIT:
Cu=1s2 2s2 2p6 3s2 3p6 4s2 3d9
   =1s2 2s2 2p6 3s2 3p6 3d9 4s2
Ca2+=1s2 2s2 2p6 3s2 3p6
Cl-=1s2 2s2 2p6 3s2 3p4

for the first question, we know X will have 13 electrons. So it'll be more obliged to give up 3 electrons to be stable in forming a compound. Hence, X3+, or if we use the periodic table, it's Al3+.

From the list, we see that:
a) Cannot work coz X gives 3 electrons but F2 only accepts 2 to be stable
b) Calcium gives 2 electrons and X gives 3 electrons....won't work for sure
c) This one works. X gives 3 electrons and Cl3 need 3 electrons. YAY!
d) Mg gives 2 while X2 gives 6. won't work.
Hence, C