Topics: Atom, Periodic table, Chemical bonding Pages: 5 (1777 words) Published: November 15, 2013
Electronegativity is a measure of the ability of an atom in a molecule to draw bonding electrons to itself. The most commonly used scale of electronegativity is that developed by Linus Pauling in which the value 4.0 is assigned to fluorine, the most electronegative element. Lithium, at the other end of the same period on the periodic table, is assigned a value of 1. Electronegativity generally increases from left to right on the periodic table and decreases from top to bottom. Metals are the least electronegative of the elements. The Pauling electronegativities for the elements are often included as a part of the chart of the elements. An important application of electronegativity is in the prediction of the polarity of a chemical bond. Because hydrogen has an electronegativity of 2.1 and chlorine has an electronegativity of 3.0, they would be expected to form a polar molecule with the chlorine being the negative side of the dipole. The difference between the electronegativities of Na(0.9) and Cl(3.0) are so great that they form an ionic bond. The hydrogen molecule on the other hand, with zero electronegativity difference, becomes the classic example of a covalent bond. After fluorine, oxygen is the next highest in electronegativity at 3.44, and this has enormous consequences in practice. Since oxygen is the most abundant element on the Earth, its high chemical activity makes it a part of most common substances. It's electronegativity leads to the polar nature of the water molecule and contributes to the remarkable properties of water.

Lewis Dot Structure.
Lewis structures (also known as Lewis dot diagrams, electron dot diagrams, "Lewis dot formulas", Lewis dot structures, and electron dot structures) are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule. A Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds. The Lewis structure was named after Gilbert N. Lewis, who introduced it in his 1916 article The Atom and the Molecule. They are similar to electron dot diagrams in that the valence electrons in lone pairs are represented as dots, but they also contain lines to represent shared pairs in a chemical bond (single, double, triple, etc.). Lewis structures show each atom and its position in the structure of the molecule using its chemical symbol. Lines are drawn between atoms that are bonded to one another (pairs of dots can be used instead of lines). Excess electrons that form lone pairs are represented as pairs of dots, and are placed next to the atoms. Although main group elements of the second period usually react by gaining, losing or sharing electrons until they have achieved a valence shell electron configuration with a full octet of (8) electrons, other elements obey different rules. Hydrogen (H) can only form bonds which share just two electrons, while transition metals often conform to a dodectet (12) rule (e.g., compounds such as the permanganate ion). Generally, elements below the second Period (Row) are able to expand their valence shells to accommodate more than 8 electrons.

Why do atoms react?
All atoms (except for the noble gases) are unstable because their outer electron shell in not full.  Atoms react with other atoms to gain or lose electons to fill their outer shell.

Describe the posible interactions between, at least, two particles. The exchange interaction is a quantum mechanical effect between identical particles. It is due to the wave function of indistinguishable particles being subject to exchange symmetry, that is, either remaining unchanged (symmetric) or changing its sign (antisymmetric) when two particles are exchanged.

Do you know the differences between atom, ion and radical?
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a...
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