How many electrons in 3rd shell?

Question 1 (b):

'How many electrons completely fill each of the following.
the third shill (n=3)'

The third shell of any atom would contain 8 electrons, according what ive been taught from year 10. However, the mark scheme disagrees with an answer of 18. :eyeball:

Anybody care to explain where im wrong.
Thanks in advance

Reply 1

daniel_williams

15

sonic23

Question 1 (b):

'How many electrons completely fill each of the following.
the third shill (n=3)'

The third shell of any atom would contain 8 electrons, according what ive been taught from year 10. However, the mark scheme disagrees with an answer of 18. :eyeball:

Anybody care to explain where im wrong.
Thanks in advance

in lower levels such as GCSE as far as you are concerned its 2, 8, 8...

I'm not sure how much you know about orbitals but they are built up of S, P, D and F.

s contains 2 electrons
p contains 6 electrons
d contains 10 electrons
f contains 14 electrons.

the first shell is made up of S1 (2)

the second shell is made up of S2(2) & P1(6) combined (8)

the third shell is made up of S3(2), D1(10) and P2(6) making 18.

its because you have to take into account the transition metals. i could make it slightly more complicated than this but i think this is the basic answer you need.

Reply 2

sonic23

OP

11

so cobalt, atomic no. 27, has outer shell electrons still in the third shell?

or is it because transition metals donate there 4s electrons to the d-subshell that makes it different.

Reply 3

Zygroth

14

The 3rd shell can hold 8 at first, then later on can contain up to 18 because the 4s orbital fills before 3d, so for cobalt the electrons would be in the 4th shell I'd assume :p:

Reply 4

DeanK2

Everyone above is incorrect.

The shell hols 2n^2 electrons. It has 18.

3s2 3p6 3d10

Reply 5

sonic23

OP

11

DeanK2

Everyone above is incorrect.

The shell hols 2n^2 electrons. It has 18.

3s2 3p6 3d10

Thats kind of what the other guy said. thanks

Reply 6

Mr Nonsense

13

daniel_williams

i could make it slightly more complicated than this but i think this is the basic answer you need.

sorry to kinda hiack the thread..... :ninja:

can i just ask you how many electrons can the 4th energy level hold? i think it is 32 - is that right? with the f block ones... are they 4th energy level??

thank you very much

Reply 7

DeanK2

Mr Nonsense

sorry to kinda hiack the thread..... :ninja:

can i just ask you how many electrons can the 4th energy level hold? i think it is 32 - is that right? with the f block ones... are they 4th energy level??

thank you very much

Sigh. This is getting tiresome. If you were to read the post two above:

Number = 2n^2, were n is the principial quatum number.

Reply 8

applemilk1992

12

it goes 1st - 2
2nd - 8
3rd - 18

DONT AGREE WITH YEAR TEN CHEMISTRY, WHAT THEY TEACH YOU IS TOTAL SANDRA BULLOCKS! :p:

remember the different orbitals, your s (holds 2 electrons), p (holds 6 electrons), d (holds 10 electrons) and f (holds 14 electrons) orbitals

"n= ..." means the nth shell.

n= 1... 1s(2) 2 electrons
n= 2... 2s(2) 2p(6) 6+2=8 electrons
n= 3... 3s(2) 3p(6) 3d(10) 10+6+2=18

and if we go onto n= 4, we get.... 4s(2) 4p(6) 4d(10) 4f(14) 14+10+6+2=32

and after that, youre delving past unit 1 AS chemistry.

Reply 9

DaveJ

The number of electrons in a shell is 2n^2.

n=3 consists of one s orbital, 3 p orbitals, and 5 d orbitals. Each orbital holds 2 electrons, so there are 18 in total.

Reply 10

Woody.

12

Exactly what DaveJ said. 2n^2 is the formula to work it out, where n is the principal quantum number, or 'shell number' to make it more simple.

Reply 11

MARIAM POLIS

Original post by sonic23

Question 1 (b):

'How many electrons completely fill each of the following.
the third shill (n=3)'

The third shell of any atom would contain 8 electrons, according what ive been taught from year 10. However, the mark scheme disagrees with an answer of 18. :eyeball:

Anybody care to explain where im wrong.
Thanks in advance

Hi,
for elements 1-20 of the periodic table, you must have the following:
- 1st shell of an atom holds 2 electrons
- 2nd shell of an atom holds 8 electrons
- 3rd shell of an atom holds 8 electrons
- 4th shell of an atom holds the rest of the electrons left over

And for the rest of the elements of the periodic table, you must have the following:
- 1st shell of an atom holds 2 electrons
- 2nd shell of an atom holds 8 electrons
- 3rd shell of an atom holds 18 electrons- 4th shell of an atom holds 32 electrons
- 5th shell of an atom holds 50 electrons
- 6th shell of an atom holds 72 electrons

How many electrons in 3rd shell?

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