2A.11

[Sophia B 3G]

Can someone explain 2A.11? I am confused and do not understand it. Thanks!

[Shria G 2D]

Hi,

M3+ means it is a metal that has lost 3 electrons which is why it has a +3 charge. Therefore, we need to find an element for which if you remove 3 electrons, it results in the electron configuration given.

(a) [Ar] 3d6
Aside from the exceptions, all of the elements in the 4th row fill the 4s orbital and then the 3d orbital. [Ar] 3d6 doesn't have any electrons in the 4s orbital so we know that 2 of the electrons removed are from the 4s orbital. One more electron needs to be removed to have a total of 3 electrons removed. The 3rd electron would be removed from the next outermost orbital which is the 3d orbital. Therefore, the 3d orbital should have 7 electrons in it so once 1 is removed, it results in 3d6 which is what the problem gave. So, the ground state electron configuration of the metal has to be [Ar] 3d7 4s2 which corresponds to Co. You can check this by looking at the electron configuration of Co3+ which would be [Ar] 3d7 4s2 with 3 electrons removed, resulting in [Ar] 3d6.

And you can do the same thing for parts b-d. I hope that makes sense!

[Melody_Tapia_1J]

So all the electron configurations they gave you are the result for some element M^3+. You don't know what element M was used, but you know that you took out three electrons to get the configuration they gave you. Therefore, you would do the reciprocal to the electron configurations they provide for you. Instead of taking away 3 electrons, you add three electrons to find out the initial element used.

[Sophia B 3G]

Hi,

M3+ means it is a metal that has lost 3 electrons which is why it has a +3 charge. Therefore, we need to find an element for which if you remove 3 electrons, it results in the electron configuration given.

(a) [Ar] 3d6
Aside from the exceptions, all of the elements in the 4th row fill the 4s orbital and then the 3d orbital. [Ar] 3d6 doesn't have any electrons in the 4s orbital so we know that 2 of the electrons removed are from the 4s orbital. One more electron needs to be removed to have a total of 3 electrons removed. The 3rd electron would be removed from the next outermost orbital which is the 3d orbital. Therefore, the 3d orbital should have 7 electrons in it so once 1 is removed, it results in 3d6 which is what the problem gave. So, the ground state electron configuration of the metal has to be [Ar] 3d7 4s2 which corresponds to Co. You can check this by looking at the electron configuration of Co3+ which would be [Ar] 3d7 4s2 with 3 electrons removed, resulting in [Ar] 3d6.

And you can do the same thing for parts b-d. I hope that makes sense!

This was really helpful! Thank you.

[Sophia B 3G]

So all the electron configurations they gave you are the result for some element M^3+. You don't know what element M was used, but you know that you took out three electrons to get the configuration they gave you. Therefore, you would do the reciprocal to the electron configurations they provide for you. Instead of taking away 3 electrons, you add three electrons to find out the initial element used.

This was helpful! Thank you.