Chem HELP!!

[li102]

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Guys I really don't understand this problem, plz help me! The answer is 3, but I can only find 2...

The electronic configuration of a particular neutral atom is 1s2 2s2 2p6 3s2 3p2. What is the number of unpaired electrons in this atom?


Oh and I also have a maths problem in case any of you would like to help me out here.

Jill has 6 different books, in how many ways can Jill select 2 different books?

I am not sure if the equation n!/(n-r)! is the right one to use here.

Thanks

 

[joonkimdds]

Guys I really don't understand this problem, plz help me! The answer is 3, but I can only find 2...

The electronic configuration of a particular neutral atom is 1s2 2s2 2p6 3s2 3p2. What is the number of unpaired electrons in this atom?

s can have 2,
p can have 6.

1s2 = good~ 2 out of 2
2s2 = good ~ 2 out of 2
2p6 = good~ 6 out of 6
3s2= good ~ 2 out of 2
3p2= aha~! 2 out of 6....and the order is up up up and down down down.
we have 2 electons so up(down is missing), up(down is missing), (both up and down are missing but it's just blank orbital).
It's true that there are only 2 unpaired electrons.
It seems the answer was considering the blank orbital(no electron) as an unpaired electron but that's wrong and u r right!

 

[joonkimdds]

Jill has 6 different books, in how many ways can Jill select 2 different books?

I am not sure if the equation n!/(n-r)! is the right one to use here.

Thanks

I believe u can use that equation.
I get 15 for the answer.

 

[li102]

The answer for number 1 is not 2 but 3🙁
and the answer for number 2 is not 15 but 30😕

This is why I posted them, I am so confused

 

[joonkimdds]

The answer for number 1 is not 2 but 3🙁
and the answer for number 2 is not 15 but 30😕

This is why I posted them, I am so confused

for the second question, does it matter which book she picks up first?
it's obvious that 15 x 2 = 30 and she can only pick up 2 books.
This must mean that which book she pick up first matters.
let's say there are only 2 different books. There is only 1 way to pick
these books. But if you pick the 2nd book first, that should be counted as
2 different ways to pick up these 2 books, right?
I am sure that's what the Q maker was thinking and all i can say is the Q maker is dumb 😀

and I explained why the answer for number 1 has to be 2.
Again, whoever made the question is....dumb
and doesn't know the difference between unpaired electron and
no electron.

Can i ask where u got these question from"? if u don't mind?

p.s. I hope I didn't offend the Q maker.

 

[hoak]

For the second question, I think this way: you have 6 different books, right. So, your first pick, you have 6 options. Your second pick, there are only 5 books left, so you have 5 options now.

The math is : 5x6= 30 ways

 

[li102]

👍 Thanks guys, I feel better now

 

[vj212306]

The answer for number 1 is not 2 but 3🙁
and the answer for number 2 is not 15 but 30😕

This is why I posted them, I am so confused

For #1: 1 electron from 3s2 will excite to 3p, make it 3p3, so there is 3 unpair of e... the reason is, there is a law, which half filled subshell is more stable, therefore it tend to happen that way (i dont remember what law it is. ) But think of Carbon when it goes sp3 hybidize, its more stable that way, so eventhough C is 2s2 2p2, it always exist at 2s1 2p3. ( This is what i would explain if the answer is 3.)

For #2: answer is 30. Cuz we pick the book randomly, so it doesnt matter which one we pick first. So, the the 1st book, there are 6 different ways to pick, for the 2nd, there is 5 different ways ( cuz we already removed one) ..so 6*5 is 30

Hope it helps

 

[PD3]

For #1: 1 electron from 3s2 will excite to 3p, make it 3p3, so there is 3 unpair of e... the reason is, there is a law, which half filled subshell is more stable

I understand that half filled subshells are more stable, but the question says a neutral atom. Does that mean that it's in its ground state configuration. Why should we assume it is in an excited state?

 

[vj212306]

I understand that half filled subshells are more stable, but the question says a neutral atom. Does that mean that it's in its ground state configuration. Why should we assume it is in an excited state?

Neutral doesnt mean have to be in ground state. Im not sure about my explaination either, but that is what I would explain if the answer is 3

 

[Mstoothlady2012]

Guys I really don't understand this problem, plz help me! The answer is 3, but I can only find 2...

The electronic configuration of a particular neutral atom is 1s2 2s2 2p6 3s2 3p2. What is the number of unpaired electrons in this atom?

well since it is 3p2...& p has 3 orbitals....first 2 orbitals will have 1 electron in each of them & the last orbital willl be empty. So unpaired electrons are 2 ...i don't know why the answer is 3.