Concepts09 - Concepts of the Experiment Matter exists in...

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Concepts of the Experiment Matter exists in three states. The face that a gas can be condensed to a liquid and a liquid frozen to a solid indicates that there are attractive forces between all molecules. We can schematically represent these forces at the surface of a liquid by the arrows in Figure 1. In the interior of the liquid, forces exerted on a given molecule are uniform in all directions. At the surface, however, it is clear that there is a net force attracting each surface molecule inward. These molecules have higher energies than interior molecules, thus giving rise to the force known as surface tension. It is because of this force that liquid droplets are spherical. A spherical shape presents the smallest surface area for a given volume. If the liquid is water, the surface tension is especially strong because particularly strong intermolecular forces, called hydrogen bonds, exist between the water molecules. (While strong for intermolecular bonds, these bonds are still considerably weaker than the intramolecular covalent bonds that bind atoms together in a molecule.) Hydrogen bonding arises whenever a hydrogen atom that is attached to a highly electronegative atom, such as oxygen, has access to an unbonded pair of electrons, such as those of another oxygen atom. Another property displayed by water is polarity. Polar molecules possess a separation of charge. In ionic compounds, such as NaCl, there is a separation of a full unit charge, Na + …..Cl - . Polar covalent molecules
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This note was uploaded on 04/10/2010 for the course CHEM 123 taught by Professor Mchale during the Fall '09 term at Rice.

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Concepts09 - Concepts of the Experiment Matter exists in...

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