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Chapter 3

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Terms in this set (33)

  • Polar Covalent Bonds

    In the water molecule, the electrons of the polar covalent bonds spend more time near the oxygen than the hydrogen.

  • Polar Molecule

    • The water molecule is thus a polar molecule;the overall charge is unevenly distributed.

    • Polarity allows water molecules to form hydrogen bonds with each other

  • Cohesion

    • Hydrogen bonds hold water molecules together, a phenomenon called cohesion.

  • Surface Tension

    • Cohesion results in high surface tension, a measure of how difficult it is to stretch or break the surface of a liquid.

  • Adhesion

    • Adhesion is an attraction between different substances,for example, between water and plant cell walls.

  • Kinetic Energy

    • Kinetic energy is the energy of motion.

  • Thermal Energy

    • The kinetic energy associated with random motion of atoms or molecules is called thermal energy.

  • Temperature

    • Temperature represents the average kinetic energy of the molecules in a body of matter.

  • Heat

    • Thermal energy in transfer from one body of matter to another is defined as heat.

  • Calorie

    • A calorie (cal) is the amount of heat required to raise the temperature of 1 g of water by 1°C.

  • Kilo calories

    • The “Calories” on food packages are actually kilo calories(k cal); 1 k cal = 1,000 cal.

  • Joule

    • The joule (J) is another unit of energy;1 J = 0.239 cal, or 1 cal = 4.184 J.

  • Specific Heat

    • The specific heat of a substance is the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C.

  • Heat of Vaporization

    • Heat of vaporization is the heat a liquid must absorb for 1 g to be converted to gas.

  • Evaporation

    • Evaporation (or vaporization) is transformation of a substance from liquid to gas.

  • Evaporative

    • As a liquid evaporates, its remaining surface cools,through a process called evaporative cooling.

    • Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water.

  • Solution

    • A solution is a liquid that is a completely homogeneous mixture of substances.

  • Solvent

    • The solvent is the dissolving agent of a solution.

  • Solute

    • The solute is the substance that is dissolved.

  • Aqueous Solution

    • An aqueous solution is one in which water is the solvent Water is a versatile solvent due to its polarity.

  • Hydration Shell

    • When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a hydration shell.

  • Hydrophilic

    • A hydrophilic substance is one that has an affinity for water.

  • Hydrophobic

    • A hydrophobic substance is one that does not have an affinity for water.

    • Oil molecules are hydrophobic because they have relatively non polar bonds

    • Hydrophobic molecules related to oils are the major ingredients of cell membranes.

  • Molecular Mass

    • Molecular mass is the sum of all masses of all atoms in a molecule.

  • Molarity

    • Molarity (M) is the number of moles of solute per liter of solution.

  • Hydrogen ion

    • The hydrogen atom leaves its electron behind and is transferred as a proton, or hydrogen ion (H+ )

  • Hydroxide ion

    • The molecule that lost the proton is now a hydroxide ion (OH-).

  • Hyronium ion

    • Hydronium ion (H30+), though it is often represented as H+

  • Acid

    • An acid is a substance that increases the H+ concentration of a solution.

  • Base

    • A base is a substance that reduces the H+ concentration of a solution.

  • pH

    • The pH of a solution is defined by the negative logarithm of H+ concentration, written as pH=-log[H+]

  • Buffers

    • Buffers are substances that minimize changes in concentrations of H+ and OH- in a solution

  • Ocean Acidification

    • CO2 dissolved in seawater forms carbonic acid; this process is called ocean acidification