Atomic Structure (1 Viewer)

[deadbeat]

<TR><TD class=heading>Question: </TD><TD>Which of the following is the correct electron structure for Calcium?

I thought the electron Structur

was 2,8,10 ??

as the 3rd shell can fit 2(n)^2 = 2x3^2 =18 electrons

so why is the answer 2,8,8,2?

why does it go to the 4th shell when the 3rd shell hasnt even been filled??</TD></TR><TR><TD class=heading></TD><TD></TD></TR><TR><TD class=heading></TD><TD></TD></TR><TR><TD class=heading></TD><TD></TD></TR>

 

[dehaitest]

(Memory a bit hazy)
I think that books deal with basics in that manner. You're not wrong. 2n^2 is the rule of thumb but books dealing with the first 20 elements,hydrogen up to calcium use from 1 to 2,8,8,2.

 

[watatank]

for senior chemistry just use 2-8-8 (two first shell, 8 next two) rule for your rule of thumb. as has been said, they only deal with the first 20 elements when it comes to atomic structure.

 

[me121]

I can't remember exactly, and you don't need to know for the Core, but you look at this in the Chemistry of Art option.

 

[boris]

I think it goes like this;
Calcium gives up its 2 valence electrons in the 4th level to expose its 8 electrons in the 3rd level. This is how it becomes a calcium ion and something about oxidation, I dunno.

 

[imnotkarl]

ok whewn dealing with electron shells there is such thing as 'half shells'
a normal structure using full shells is shown something like this 2,8,18,(creating awkward-looking structures)
so to make them look "pretty" we us half shells.
using half shells you can "break down" bigger shells. ie. 2,8,8,2 (which is your answer for Calcium.)

***note*** if shells are halved, the ionisation power changes and with that so does the electro-negativity and atomic radius.

 

[tommykins]

The first 5-6 shells can have 2,8,18,32,50 electrons respectively.
In order to illustrate this rule, I will use Zinc (Atomic Nmber 30) as an example.

The basic rule is, you need to add 2 electrons in the suceeding shell, before you're able to complete the previous shell which has been added with 8 electrons.

For Zinc, you fill the first shell with 2 electrons, you now have 28 electrons you need to fill.

The second shell has a maximum of 8, so you can fill that up, you now have 18 electrons left.

THe third shell can have a maximum of 18, BUT the rule is, you need to fill the shell you're at to 8 electrons, and then add 2 to the next shell before being able to complete your current shell.

Therefore, the third shell is filled to 8 electrons, meaning you have 10 electrons left.

With the remaining 10 electrons, you need to fill the forth shell with 2 electrons before completing the third shell. +2 on the fourth, you now have 8 left.

Since you have 8 electrons on the third shell and 2 on the fourth, you can now complete the third shell, and thus add 8 electrons to it - totalling at 16 electrons on the third shell.

Hence, Zinc's atmoic structure is 2,8,16,2.

All this has to do with the stability of the atom and energy levels of the shells.

Pretty much - Reach 8, fill the next shell with 2, then you can continue filling the shell you were initially at with yuor remaining electrons.

 

[minijumbuk]

You can't fill the third shell with more than 8 electrons until the fourth shell is filled with 2 electrons.

 

[brenton1987]

This is a fairly complicated concept so this is only very basic.

It is based on the electron energy in the subshells of the atomic orbitals. Electrons will fill from the lowest energy shells to the highest energy shells.
The order of filling is:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, 8s

Looking at the periodic table, groups 1 and 2 are called the s-block, groups 13-18 are the p-block, groups 3-12 are the d-block and the lanthanides and the actinides are the f-block.

If you fill up the electrons in the correct order you will notice that they are added in a linear fashion across the table.