Atoms consist of three main particles: protons, neutrons and electrons. The atomic nucleus is built of protons and neutrons, while the electrons whiz around the nucleus forming an electron cloud. The electron cloud has different energy levels called electron shells. Electrons from the outer electron shell are called valence electrons. The valence electrons take part in chemical bonding.When a chemical bond is being formed the atoms aim at attaining a full outer electron shells and so become stable. The fundamental cause for binding of atoms and formation of chemical bonds is the lowering of the energy with the process.

"Chemisstry is the science of molecules and their transformations. It is sience not so much of the elements, but of the variety of molecules that can be build from them." Roald Hoffmann

• Structure of the atom
• Stable outer electronic layer at forming a chemical bond
• Octet rule
• Problems and tests

Structure of the atom

http://www.purchon.com/chemistry/atoms.htm Atomic models of carbon, deuterium, tritium, and helium;

http://chem4kids.com/files/atom_structure.html Electronic shell.

http://www.usm.maine.edu/~newton/Chy251_253/Lectures/BohrModel/BohrModelFS.html The Bohr model of a hydrogen atom and emission spectrum of hydrogen.

http://www.wpbschoolhouse.btinternet.co.uk/page04/4_71atom.htm Periodic table and electronic structure of the atom.

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Stable outer electronic layer at forming a chemical bond

http://www.s-cool.co.uk/topic_principles.asp?loc=pr&subject_id=21&topic_id=2 Formation of new compounds and examples of forming ionic and covalent bonds; type of solids.

http://www.usm.maine.edu/~newton/Chy251_253/Lectures/LewisStructures/DihydrogenFS.html Change of the potential energy of two hydrogen atoms at chemical bond formation.

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The octet rule. Obtaining stable electronic configuration - full outer shell of electrons.

http://www.wpbschoolhouse.btinternet.co.uk/page03/Noble_Gases.htm Noble Gases - electronic configuration and properties.

http://schoolchem.com/xinoblegases.htm More information for Noble Gases.

http://www.chem.uncc.edu/faculty/murphy/1251/slides/C18a/sld004.htm Visualisation of the octet rule.

http://www.westga.edu/~chem/courses/chem1212slattery/contents/chapter8-all/sld011.htm Octet rule for cations.

http://www.westga.edu/~chem/courses/chem1212slattery/contents/chapter8-all/sld013.htm Octet rule for anions.

http://ull.chemistry.uakron.edu/genchem/09/ Octet rule exceptions

http://schoolchem.com/xa4.htm All chemical reactions involve atoms trying to get a full outer shell of electrons.

http://www.wpbschoolhouse.btinternet.co.uk/page04/4_72bond.htm Main types of bonding: covalent, ionic, bonding in metals.

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Problems and tests

http ://207.10.97.102/ chemzone / lessons /03 bonding / dogbonds . htm   Comparison of different bonds.

http :// www . odonel . k 12. nf . ca / science / tut - bond / problems . htm Nature of the chemical bond.

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