periodic table shells help?

Question

can someone please explain what shells are on elements and how you determine how many there are etc

Answer 1

Electrons are said to be located on shells in an atom. The no. of shells depends on the no of electrons in the atom. The generally the no. of electrons that can hold on the inner shell is 2 then 8 and 8 and 2 for the second, third and fourth shell.



So for eg if you wanted to know how many shells there were in an oxygen atom (atomic no. is 8), you know that 2 electrons would be on the first shell, and the second shell would have the remaining 6 electrons since that shell can hold up to 8. (So oxygen would have 2 shells... one with 2 electrons and one with 6)



Also you can tell what group(of the periodic table) an atom is in by the no. of electrons in its outer shell. Therefore oxygen would be in group 6.



Hope this helps :)

Answer 2

The elements in each row of the periodic table contain same number of shell.



For example, the first row elements have 1 shell, the second row's have 2 shells, the third row's have 3 shells, and so on...

Answer 3

It's the way electrons are arranged around atoms.



Shells are subdivided into subshells and there are four kinds of these:



s which can hold up to 2 electrons

p which can hold up to 6 electrons

d which can hold up to 10 electrons

f which can hold up to 14 electrons



The first shell contains only one s subshell (can hold up to 2 electrons)

The second shell contains one s and one p subshell (can hold up to 8 electrons)

The third shell contains one s, one p and one d subshell (can hold up to 18 electrons)

The fourth shell contains one s, one p, one d and one f subshell (can hold up to 32 electrons)



For example an atom that has 17 electrons it will put them in:



the first shell: 2

the second shell: 8

the third shell: 7



In this case the third shell is the last or outer shell.



You will find that all elements in a group of the periodic table have a similar outer shell electron configuration e.g all the elements in group two, beryllium, magnesium, calcium, strontium, barium and radium have just two electrons in their outer shell.