Sodium, assuming "first" means "first in the Periodic Table", i.e. the one with fewest electrons per atom. The first shell holds 2 electrons, and the second holds another 8. So the element with atomic number 11 is the first one to need the third shell, and that's sodium.
The first shell can hold a maximum of 2 electrons, the second shell can hold up to 8 while the third shell can also hold a maximum of 8.
Elements having electrons in their third valence shell can be found in the third row of the periodic table (elements 11-18).
Chlorine has 17 electrons, distributed in the following way: 2 in first shell 8 in second shell 7 in third (outer) shell Therefore Chlorine has 7 electrons in its outer shell.
First you start of by finding out what the atomic number is of the element, in this case the number is 17. You then draw a circle, you are aloud to put 2 electrons on this circle. you then draw another cirlce around it, you are aloud to have 8 electrons on the outer shells. you will ned a third circle to put the rest of the elcetrons on to it. in total you should have the smallest circle with 2 electrons, the middle circle with 8 and then the outer shell with 7 elecrons on it. you can draw the electrons as dots or crosses on the cirlce line. because the outer shell is not full and only has 7 electrons instead of 8, this means it will be reactive. if an element has a full outer shell then it becomes unreactive. hope that helped. :)
The simply answer is that in the outer shell each of the halogens have only seven electrons, this is the reason why they are the most reactive nonmetals, they wish to require a further electron to become stable. Fluorine (F) Atomic number 9 [He] 2s22p5 note the second shell is the outer shell and has only 7 electrons, to be stable it has to have eight. Chlorine (Cl) Atomic number 17 [Ne] 3s23p5 note this its the third shell which is the outer shell and has only 7 electrons, to be stable it has to have eight. For Bromine (Br) we find its the fourth shell is the outer shell which has seven elections, and finally Iodine (I) we find its the fifth shell which is the outer shell and it has only 7 electrons, to be stable it has to have eight. Hope this helps
It is sodium Chlorine is the first element that needs a third shell.
This element is sulfur (S), with 2 electrons in the first shell, 8 electrons in the second shell, and 6 electrons in the third shell.
sulphur
Silicon.
Sulfur
What element has 2 electrons in the first shell and 8 in the second and 6 in the third
The answer is Sulphur
The element that has 7 valence electrons in its third shell is chlorine. The electronic configuration of chlorine is 2, 8, 7, with the outermost shell containing 7 electrons.
The number of electrons in a shell is 2n2, where n=shell number. So for the first shell, there is a maximum of 2 electrons.
The electron configuration of an element with atomic number 15 (phosphorus) is 1s2 2s2 2p6 3s2 3p3. This means it has 2 electrons in the first shell, 8 in the second shell, and 5 in the third shell.
Sulfur
Sulfa.