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Electron-Dot Diagrams & Properties

Electron-Dot Diagrams & Properties

Electron-Dot Diagram - SodiumIntroduction: In our modern world, it is important to understanding how different elements react. Some elements react similarly. For example, sodium and francium react rather violently when placed in water. Chlorine - a rather dangerous and potentially fatal gas - and iodine - a purple solid that sublimes at room temperature - react strongly with metals like sodium and francium. In both instances, the similarities in the chemical behavior of certain elements can be explained by similarities in the number of valence electrons, or electrons in the outermost shell of the atom of an element. Valence electrons are significant because they play an incredibly important role in determining how the element bonds.

To represent the atomic structures of different elements more easily for the purposes of comparison, Lewis electron-dot diagrams are used. These diagrams are diagrams that represent the valence electrons in the atom of a specific element. In a Lewis electron-dot diagram, the chemical symbol of the element is written to represent the nucleus and the inner electrons of the atom. Around the chemical symbol are dots, which represent the valence electrons of the atom of the element. For example, in the electron-dot diagram of sodium shown above, the symbol "Na" represents the nucleus and inner electrons of sodium, while the dot next to the symbol represents sodium's 1 valence electron. Generally, elements tend to have similar chemical properties and the same number of valence electrons if they are in the same group, or vertical column, on the Periodic Table. In certain cases, elements will either lose or gain valence electrons to form ions, or charged forms of atoms. For example, sodium and francium, both being in Group 1 with one valence electron, will tend to lose 1 valence electron to form a +1 ion. Chlorine and iodine, on the other hand, being in Group 17 with seven valence electrons each, will tend to gain 1 valence electron to form a -1 ion. Specific elements will react in specific ways to attain an octet, or a stable electron configuration of 8 valence electrons, equivalent to the electron configuration of an element in Group 18.

When the number of electrons in an ion equals the number of electrons in an element, the ion and the element are said to be isoelectronic. For example, an ion of sodium, having 10 electrons, is isoelectronic with neon. An ion of chlorine, having 18 electrons, is isoelectronic with argon. The number of electrons found after losing or gaining electrons to form the ion is simply compared to the number of electrons in a specific element to find which element it is isoelectronic with. The chemical formula of a compound formed between two ions, one being positive and the other being negative, can be found by crossing the charges of the ions, then reducing the formula to have the lowest numbers possible.


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