Review: Water the Highway of Life
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A covalent bond is formed when atoms share electrons to complete their valence energy levels.
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An atom can have one to eight valence electrons.
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An ion is an atom that has gained or lost one or more electrons and has become charged.
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Bohr-model diagrams can be used to show how atoms bond to one another forming molecules.
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Charcoal and sand filters remove any remaining dirt, bacteria, and odor.
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Charge distribution for a water molecule:
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Chlorine kills bacteria.
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Concentration gradient is the
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Conductivity is the difference in concentration of a given particle at two points in a space.
ability of a substance or solution to conduct electricity.
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Covalent bonds share electrons; ionic donate and accept electrons.
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Diffusion is the net movement of particles from an area of high to an area of low concentration.
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Diffusion is vital to living cells because nutrients and wastes can be transported across the cell membrane.
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Diffusion occurs by kinetics; dispersion results from mixing.
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Hard water substances come from rock formations that the water comes in contact with.
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Hydrogen bonds are formed between negatively and positively charged particles.
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In the water molecule, the oxygen atom is bonded to two hydrogen atoms in the shape of a "V"
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Ionic bond is the result of an attraction among positive and negative ions.
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Ionic compounds are generally composed of metal and non-metal ions that form due to of electron transfer .
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Ions enable a solution to conduct electric current.
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Kinetic molecular theory says that all particles are in constant motion. You would therefore expect solutes to dissolve more quickly in hot water than in cold.
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Knowing the conductivity of a solution tells us if the solute is ionic or molecular.
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Molecular compound atoms are bonded covalently; non–metal elements sharing electrons.
 Moving from a more to a less concentrated zone in a solution is moving “down the concentration gradient”.
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Osmosis is a process used by cells to obtain oxygen, water and nutrients and remove wastes in solution.
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Polar molecules have one slightly positive and one slightly negative end, due to uneven charge distribution.
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Positive ions are formed when atoms lose electrons; negative ions are formed when atoms gain electrons.
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Precipitate is the low solubility product of a chemical reaction that occurs in solution.
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Precipitates settle out of the water.
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Salt in ocean water comes the sea floor and from minerals washed down by streams.
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Solute is a substance which becomes dissolved in solution.
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Solvent is a substance which dissolves matter.
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Stable atoms always have the same number of protons as electrons.
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Table salt is a compound composed of sodium and chloride ions.
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The Bohr model of the atom assigns exact limits of electrons for each energy level.
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The compound most likely responsible for "hard" water is calcium carbonate.
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The electron is the negative charge carrier in an atom.
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The rate of dissolving a solute in a solvent can be increased by heating and stirring.
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The two solutions used in the video to give medication intravenously were saline and dextrose.
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The water molecule is polar. That is one side of the molecule is slightly more positively, and the opposite side is slightly more negatively charged due to uneven charge distribution
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Valence electrons are located in the energy level farthest from the nucleus of an atom.
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Water called the universal solvent because its polarity enables it to dissolve many kinds of solids.

 Water is “hard” when it contains: a lot of dissolved calcium and magnesium compounds.
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Water is special in that it can dissolve many, but not all, substances.
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Water's ability to dissolve most substances is mostly due to it being a polar molecule.
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When a metal donates electrons it becomes a positive ion.
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When a solution’s concentration progressively changes from one area to another, it is called concentration gradient.