<< Chapter < Page Chapter >> Page >


The electron shell model for the atom provides significant answers to many of the most important questions about the properties of atoms. For many of the problems that chemists need to solve, we don’t need more details about the structure of the atom than what we can gain from knowing the numbers of electrons in the valence shell, the size of the valence shell, and the charge on the nucleus. As perhaps the best example of this, the Periodic Law of the elements is easily understood from the repeating pattern of filling a valence shell successively and starting over with a new shell. Even though more advanced and detailed theories of atomic structure have come along since the electron shell model was introduced, chemists return to this simple model to understand the properties of elements and the structures and reactions of molecules. We shall come back and explore these applications of the electron shell model in later Concept Development Studies.

For now, there are still some nagging questions about this simple model. What does it mean for two or more electrons in an atom to be “in the same shell”? We don’t have a model for what a shell is, other than a set of electrons which appear to be at about the same distance from the nucleus. But this does not give a clear picture of what the electrons are doing. We have said that the electrons move in the empty space surrounding the nucleus, but we have not yet asked how they move or where they move. Without knowing that, we cannot really know why electrons have similar or different energies.

Probably the most important unanswered question is why the shells fill up. The arrangement of elements into groups and the periodicity of chemical properties both depend on the idea that a shell is “filled” by a certain number of electrons. Why is there a limit on the number of electrons which can “fit” into a shell? Looking at the number of elements in each period, the number of electrons which fills a shell depends on which shell is being filled. There are 8 elements from lithium to neon and from sodium to argon, telling us that 8 electrons will fill the valence shells in each of those sets of elements. However, there are 18 elements from potassium to krypton and from rubidium to xenon, telling us that 18 electrons will fill the valence shells in each of those sets of elements. In the cases of hydrogen and helium, only 2 electrons will fill their shell. What determines how many electrons can “fit” in a shell? What is special about the numbers 2, 8, and 18? Why is there a limit at all? These may seem like questions about only technical details. But the power of the electron shell model rests on these details, so we should find out the answers to these questions.


In this study, we will assume that we know the postulates of the Atomic Molecular Theory and our measurements of relative atomic masses. We know that an element is composed of individual atoms with identical masses, and we know that the atoms of different elements have different masses, which have been measured.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Concept development studies in chemistry 2012. OpenStax CNX. Aug 16, 2012 Download for free at http://legacy.cnx.org/content/col11444/1.4
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Concept development studies in chemistry 2012' conversation and receive update notifications?