Quiz 3

• Covalent bonds


  Bonds where atoms share their electrons in order to fill their energy shells
• Dissociation of a Water Molecule

  1. Produces hydrogen ion (positively charged)

  2. Produces hydroxide ion (negatively charged)
• Ionization


  The process by which ions are formed by gain or loss of an electron from an atom or molecule
• pH Scale


  A scale ranging from 1-14 that measures how acidic an object is
• The pH Scale measures water with the neutral value of seven while pH values below 7 are acidic and values above 7 are basic
• Acids


  Compounds that release hydrogen ions in solution, sour in taste, turn litmus paper to red, pH level: between 0-6
• Acids


  • ascorbic acid, acetic acid in vinegar, citric acid in fruits, carbonic acid in soft drinks, and hydrochloric acid in stomach
• Bases


  Substances that accept hydrogen ions and release hydroxide ions, bitter in taste, turn litmus paper into blue
• Bases


  • sodium hydroxide in soap, ammonium hydroxide in ammonia, magnesium hydroxide in laxatives and antacids
• Bases in the Body


  • sodium bicarbonate by the pancreas and the bile produced by the liver
• Acid-Base Reaction


  When hydrochloric acid combines with sodium hydroxide, it forms the salt (sodium chloride) and water as by-product
• Biological Buffers


  Organic substances that maintain a constant pH over a given range by neutralizing the effects of hydrogen ions
• The pH of the cell's internal environment stays fairly neutral between 6.6 to 7.5, where most of the vital cellular processes take place
• Electrolytes


  Compounds that can be acid, base or salt, either cations that move to positively charge electrodes or anion that move to negatively charge electrodes
• Electrolytes


  • Sodium chloride, bicarbonate, phosphate, sulfate, calcium, potassium, and magnesium
• Water


  The most abundant inorganic compound inside the cell's protoplasm, making up to 75 to 85 percent
• Water


  • Its polarity and tendency to form hydrogen bonds gives water its unique characteristics and functions
  • It is a biological solvent with the ability to dissolve many substances, including important molecules in biological systems
• Water as a biological solvent


  • Water can dissolve the salt crystals due to water's polarity
• Water


  • Cohesion- ability of water molecules to stick with one another
  • Adhesion- ability of water molecules to cling to other polar surfaces
• Water


  • High surface tension due to hydrogen bonding, water molecules strongly attract one another, particularly on the surface of water
  • High heat capacity - a relatively large amount of energy (heat) is needed to raise the temperature of water
  • High heat of vaporization - large amount of heat is needed to turn liquid water into gas vapor
  • High heat fusion - large amount of heat must be removed from the liquid water to turn it into solid state
• Water


  • It provides a medium for the breakdown and the formation of food, absorption, secretion and excretion
  • It acts as a lubricant, preventing friction in joints during movement, in the heart during contraction, and in the intestines during digestion
  • It acts as a good cushion, with water in the cerebrospinal fluid protecting the brain and the spinal cord