Notice that the atoms with eight valence electrons

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notice that the atoms with eight valence electrons - the noble gases - are particularly stable because they have a full outer shell, an octet two electron dots are known as a duet, in the case of Helium the duet configuration is particularly stable because the n = 1 quantum level fills with only two electrons Lewis Theory's chemical bond: a chemical bond is the sharing or transfer of electrons to attain stable electron configurations for the bonding atoms when atoms are shared, this type of bonding is known as covalent bonding. When atoms are transferred they are known as ionic bonds stable electron configurations are usually known as eight electrons in the outermost shell known as the octet rule Although the Lewis theory's strength lies in covalent bonding it can also be used in ionic bonding we move the electron from the metal to the nonmetal and the resulting structure is a crystalline composed of alternating cation and anions Ionic bonding and electron transfer:
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consider potassium and chlorine when these atoms bond, potassium transfers its valence electron to chlorine: the transfer leaves chlorine with a full outer shell (octet) and potassium with a full outer shell (octet) in the previous shell (and without any valence electrons in its original outermost shell) the potassium becomes a cation because it has lost an electron while the chlorine becomes an anion because it has gained an electron the lewis charge of an anion is usually written with brackets and the charge in the upper right hand corner the resulting positive and negative charges attract each other, which leads to the resulting ionic compound of KCl the Lewis structure predicts a ratio of one potassium cation to every one chloride anion Sodium and Sulfur in a different example of sulfur and sodium: sodium must lose one valence electron to gain an octet in its outer level while sulfur must gain two electrons to obtain an octet in its outer level the lewis structure is: the two sodium atoms each lose their one valence electron while the sulfur atom gains two electrons and gets an octet the lewis model predicts Na(2)S just as it appears in nature Lattice Energy: The rest of the story the formation of an ionic compound from its constituent elements is usually quite exothermic for example:
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the transfer of an electron from sodium to chlorine actually absorbs energy , the ionization energy of sodium is + 496 kJ/mol while the electron affinity of Cl is only -349 kJ/mol, which leaves an endothermic reaction of +147 kJ/mol, but this is not the case , why? Lattice energy Lattice energy is the energy associated with forming a crystalline lattice of alternating cations and anions from the gaseous ions since the sodium ions are positively charged and the chlorine ions are negatively charged the potential energy decreases as the ions get closer together to form a lattice - the potential energy is emitted as heat when the
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