Gen Chem Question

[Utes]

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Okay, this is probably a pretty simple question to most of you since you all score 27's on Gen Chem... but here it goes:

The question wants to know the electron configuration of Zn 2+
I figure that Zn 2+ is the same as Ni. So it has 28 electrons. There were 2 answer choices with the correct amount of electrons:
[Ar] 4s2 3d8
[Ar] 4s0 3d10

I put the first answer because 4+0 =4 is lower than 3+2 = 5 and so 4s should fill first. The answer is the second one though. Why? Is there some kind of trend or rule that I need to remember that I don't recall?

Thanks,
Utes

 

[dentwannabe]

Okay, this is probably a pretty simple question to most of you since you all score 27's on Gen Chem... but here it goes:

The question wants to know the electron configuration of Zn 2+
I figure that Zn 2+ is the same as Ni. So it has 28 electrons. There were 2 answer choices with the correct amount of electrons:
[Ar] 4s2 3d8
[Ar] 4s0 3d10

I put the first answer because 4+0 =4 is lower than 3+2 = 5 and so 4s should fill first. The answer is the second one though. Why? Is there some kind of trend or rule that I need to remember that I don't recall?

Thanks,
Utes

yea, the rule is when there is a d and s orbital, the electrons will empty the S orbital FIRST! then the d orbital. its just a rule.. in kaplan book, u can find it in the orbital section.

 

[Utes]

thank you for your very quick reply!

 

[mahme]

I have another gen chem question that I seem to always have trouble with:

How many carbon atoms are there in 4.0x10^-8 grams of C3H8?

I thought it would be finding how many moles of C3H8 there is in that amount and then multiplying that by avagadro's #. Then using a ratio of 3/11 multiplied by that # of C3H8 molecules...

 

[dentwannabe]

I have another gen chem question that I seem to always have trouble with:

How many carbon atoms are there in 4.0x10^-8 grams of C3H8?

I thought it would be finding how many moles of C3H8 there is in that amount and then multiplying that by avagadro's #. Then using a ratio of 3/11 multiplied by that # of C3H8 molecules...

oh yea?

i thought you would..
4.0x10^-8 grams * 1 mol C3H8/ mass g C3H8 * 3 mol C/1 mol C3H8 * 6.022 *10^23 atoms/ 1 mol C

sumone help... i thought this was easy.. 😕

 

[mochafreak]

oh yea?

i thought you would..
4.0x10^-8 grams * 1 mol C3H8/ mass g C3H8 * 3 mol C/1 mol C3H8 * 6.022 *10^23 atoms/ 1 mol C

sumone help... i thought this was easy.. 😕

That looks right. 🙂