Chapter 2: Basic Chemistry

Matter

  • Anything that occupies space and has weight

Solids

  • Has a definite shape and volume
  • Molecules held in a fixed pattern but vibrating slightly

Liquid

  • Takes the shape of its the container
  • Molecules packed close together in a random fashion but free to move

Gas

  • Expands to fill container
  • Molecules widely separated
  • Molecules move at great speed

Physical Changes

  • Change in physical appearance
  • Composition of matter unchanged

Chemical Change

  • Chemical composition of matter changes
  • Different matter at end of chemical change

Elements

  • All mater is composed of elements
  • A fundamental substance that cannot be broken down into simpler form
  • 96% of body weight made up of four elements
  • carbonC18.5%
  • hydrogenH9.5%
  • oxygenO65%
  • nitrogenN3.2%

Atoms

  • Elements are made up of individual atoms
  • The smallest unit of an element that still posses the element’s chemical characteristics
  • 3 subatomic particles
  • Protons
  • Neutrons
  • Electrons

Structure of Atoms

  • Nucleus
  • In the center of the atom
  • Protons
  • Have a positive electrical charge (+)
  • Neutrons
  • Have no electrical charge (o)
  • Electron Shells (Orbits)
  • Electrons
  • Have a negative electrical charge (-)
  • Also called orbits
  • Found around the nucleus
  • 1st shell (inner shell)
  • 2 electrons maximum
  • 2nd shell
  • 8 electrons maximum
  • 3rd shell
  • 8 electrons maximum

Individual Atoms

  • Atoms distinguished by the number of subatomic particles it contains
  • Hydrogen
  • 1 proton
  • 0 neutrons
  • 1 electron
  • Helium
  • 2 protons
  • 2 neutrons
  • 2 electrons
  • Carbon
  • 6 protons
  • 6 neutrons
  • 6 electrons

Atomic Number vs. Atomic Weight

  • Atomic Number
  • The number of protons in the nucleus
  • Hydrogen 1
  • Helium 2
  • Carbon6
  • Atomic Weight
  • The number of protons and neutrons in the nucleus
  • Hydrogen 1
  • Helium4
  • Carbon12

Isotopes

  • Different form of the same atom
  • Same atomic number
  • Same number of protons
  • Different atomic weight
  • Different number of neutrons

Radioactive Isotopes

  • Isotopes are often unstable
  • The nuclei break down (decay)
  • Give off energy waves or radiation
  • called radioactivity
  • Called radioisotopes

Electron Shells and Stability

  • The electrons in an atoms outermost shell (valence shell) are important for bonding
  • 1st shell holds 2 electrons
  • 2nd and 3rd shells hold 8 electrons each
  • A shell is unstable if it doesn’t hold the total number of electrons
  • The shell wants to become stable by gaining or loosing electrons
  • This allows chemical bonding

Chemical Bonds

  • Two or more atoms bond together to form molecules
  • 3 types of chemical bonds
  • Ionic bonds
  • Covalent bonds
  • Hydrogen bonds

Ionic Bonds

  • Caused by transfer of electrons between atoms
  • Strong bond

Covalent Bonds

  • Happens when atoms share electrons
  • Extremely strong bond

Carbon

  • Always forms covalent bonds
  • Four electrons in outer shell
  • One of the major elements of the body
  • Bonds with hydrogen, nitrogen, oxygen and itself to form carbohydrates and proteins
  • Whole branch of chemistry dedicated to carbon-containing substances
  • Organic Chemistry

Hydrogen Bonds

  • Formed when slightly positive and negative ends (dipoles) form on molecules
  • These partial charges attract each other
  • Water
  • Makes water the universal solvent
  • DNA
  • Helps shape DNA into double helix

Ions

  • Formed when electrons are lost or gained
  • Changes the charge of the atom
  • Normally atoms are neutral (no charge)
  • Electron (-) lost  positive charge
  • cation
  • Electron (-) gained  negative charge
  • anion

Sodium Ion

  • Sodium has 11 protons+ and 11 electrons-
  • 2 electrons in the 1st shell
  • 8 electrons in the 2nd shell
  • 1 electron in the 3rd shell
  • Looses 1 electron so outer shell is stable
  • Now has 11 protons+ and 10 electrons-
  • Net charge of 1+
  • Cation
  • Na+

Chlorine Ion

  • Chlorine has 17 protons+ and 17 electrons-
  • 2 electrons in the 1st shell
  • 8 electrons in the 2nd shell
  • 7 electrons in the 3rd shell
  • Gains one electron so the outer shell is stable
  • Now has 17protons+ and 18 electrons-
  • Net charge of 1-
  • Anion
  • Cl-

Electrolytes

  • A substance that forms ions when dissolved in water
  • Sodium Chloride (NaCl)
  • Disassociates into Na+ and Cl-
  • Sodium Bicarbonate (NaHCO3)
  • Disassociates into Na+ and HCO3-
  • Potassium Chloride (KCl)
  • Disassociates into K+ and Cl-

Molecules and Compounds

  • Two or more atoms bond together to form molecules
  • Compounds are molecules made from different atoms
  • O2 Molecule
  • H2 Molecule
  • H2OMolecule and Compound

Special Properties of Water

  • 60% - 70% of body weight is water
  • Water is polar
  • Substances that are hydrophilic will react with water
  • Substances that are hydrophobic will not react with water
  • Universal Solvent
  • Most things disassociate in water
  • Solute (dissolved particles)
  • Solvent (what particles are dissolved in)
  • water
  • Disassociation facilitates chemical reactions
  • Allows movement of substances throughout body
  • Temperature regulation
  • Helps maintain stable body temperature (homeostasis) at 37 °C
  • Lubrication
  • Major component of mucus
  • Necessary for metabolism
  • Plays crucial role in chemical reactions
  • Protective device
  • Helps cushion organs like the brain

Chemical Reactions

  • Molecules or compounds interact to form new chemical combinations

Rates of Chemical Reactions

  • Most chemical reactions are very slow
  • Catalysts speed up chemical reactions
  • Protein catalysts are called enzymes
  • Inhibitors slow down chemical reactions

Acids

  • An electrolyte that disassociates into a hydrogen ion (H+) and an anion.
  • Vinegar (acetic acid)
  • CH3COOH  CH3COO- + H+
  • Sulfuric acid
  • H2SO4  HSO4- + H+
  • Hydrochloric acid
  • HCl  Cl- + H+

Base

  • Hydrogen ion (H+) acceptor
  • Usually contain hydroxyl ion (OH-)
  • Sodium hydroxide
  • NaOH  Na+ + OH-
  • Potassium hydroxide
  • KOH  K+ + OH-
  • Ammonia
  • NH3 + H2O  NH4+ + OH-

Strong vs. Weak

  • Strong acids (bases) dissociates completely
  • Weak acids (bases) do not dissociate completely

Neutralization of Acids and Bases

  • Combine an acid and base
  • H+ and OH- combine to form water
  • Anion and cation combine to form electrolyte
  • Acid and base combine to produce water and a salt

pH

  • Measurement of H+ in solution
  • Neutral
  • H+ = OH-
  • Acidic
  • More H+ than OH-
  • Basic
  • Fewer H+ than OH-

pH Scale

  • Ranges from 0 to 14
  • Neutral = 7
  • Acidic = less than 7
  • Basic = more than 7

pH of Body Fluids

  • Stomach contents
  • Very acidic
  • Intestinal contents
  • Basic (alkaline)
  • Blood
  • Narrow range 7.35 – 7.45
  • Acidosis pH below 7.35
  • Alkalosis pH above 7.45

Energy

  • The ability to do or perform work
  • Six forms of energy
  • Mechanical – energy that causes movement
  • Chemical – energy stored in chemical bonds
  • Electrical – energy released from the movement of charged particles
  • Radiant – energy that travels in waves
  • Thermal – energy transferred due to a temperature difference
  • Nuclear – Energy released during the decay of radioactive substances

Energy Conversion

  • Energy can be converted from one form to another
  • Muscle contraction
  • Chemical energy in muscle converted into mechanical energy
  • Accompanied by the release of heat (thermal energy)

Energy Transfer: ATP

  • Chemical energy in food is released as food is digested
  • Energy must be transferred to ATP so cells can use it
  • ATP: adenosine triphosphate
  • Energy storage molecule
  • High energy bonds in phosphate groups can be broken to release energy
  • Energy from food used to produce ATP

Mixtures, Solutions and Suspensions

  • Mixture
  • Can be separated by physical means
  • When separated substances retain their original properties
  • Solution
  • Type of mixture
  • The particles mixed together remain evenly distributed
  • Example: salt water
  • Solute
  • The substance present in the smaller amount
  • Substance being dissolved
  • Solvent
  • The substance present in the greater amount
  • Substance doing the dissolving
  • Aqueous solution (solvent is water) or tincture (solvent is alcohol)
  • Suspension
  • Type of mixture
  • Particles are relatively large and tend to settle out
  • Colloidal suspension – particles remain suspended
  • Colloid – gel-like substance that resembles egg whites
  • Blood plasma, mayonnaise, jellies