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We further assume the structure of the atom as a massive, positively charged nucleus, whose size is much smaller than that of the atom as a whole, surrounded by a vast open space in which negatively charged electrons move. These electrons can be effectively partitioned into a core and a valence shell, and it is only the electrons in the valence shell which are significant to the chemical properties of the atom. The number of valence electrons in each atom is equal to the group number of that element in the Periodic Table.

We will base much of our work on understanding the Periodic Law, which states that the chemical and physical properties of the elements are periodic functions of the atomic number. Finally, we will assume an understanding of Coulomb’s Law, which describes the attractions and repulsions amongst charged particles.

Observation 1: valence and the octet rule

To begin to understand chemical bonding, we will examine the valence of an atom, which is defined as the atom’s most common tendency to form bonds to other atoms. We can figure these out by looking at some common molecular formulae for molecules formed by each atom. We’ll start with the easiest case, the atoms of the noble gases. Since these atoms do not tend to combine with any other atoms, we will assign their valence as 0, meaning that these atoms tend to form 0 bonds. This doesn’t really get us very far.

To find the valence of an atom which does form bonds, let’s pick molecules which contain only a single atom of the type we’re interested in and see how many other atoms it can combine with. Oxygen is a good place to start. For example, a single O atom will combine with two H atoms to form the most common molecule H 2 O. Only under rare circumstances would we find any other combination of H and O in a neutral molecule. As such, it appears that the valence of an O atom is 2. Next we consider hydrogen, which combines with virtually any other element except the noble gases. Compounds containing hydrogen can contain a huge variety of the number of H atoms. However, molecules with a single H atom most typically contain only a single other atom, for example HF. A single C atom can combine with four H atoms, but a single H atom typically does not combine with more than one other atom. We do not typically see molecules like C 4 H. A conspicuous feature of molecules containing hydrogen is that there are typically many more hydrogen atoms than other atoms. For example, hydrogen in combination with carbon alone can form CH 4 , C 2 H 6 , C 8 H 18 , and many others. These observations lead us to conclude that an H atom has a valence of 1, meaning that a single H atom will typically only form 1 bond to another atom. This seems reasonable, since each H atom contains only a single proton and a single electron. This conclusion also is consistent with our conclusion that O atoms have a valence of 2, since the most common hydrogen-oxygen molecule is H 2 O.

We can use hydrogen’s valence of 1 to find the valence of other atoms. For example, the valence of C must be 4, since one C atom can combine with 4 H atoms, but not 5, and typically not 3. Nitrogen atoms have a valence of 3, to form NH 3 . Fluorine atoms have a valence of 1, to form HF molecules.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
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.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Concept development studies in chemistry 2013. OpenStax CNX. Oct 07, 2013 Download for free at http://legacy.cnx.org/content/col11579/1.1
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