Chapter 02 - Chemical

• Matter


  Anything that occupies space and has mass
• Mass


  • The amount of matter in an object
  • International unit for mass = kilogram (kg)
• Weight


  The gravitational force acting on an object of a given mass
• Elements


  • Oxygen
  • Carbon
  • Hydrogen
  • Nitrogen
• About 96% of the body's weight results from the elements oxygen, carbon, hydrogen, and nitrogen
• The majority of the body's weight is from oxygen
• Oxygen is the most abundant element in the earth's crust
• Carbon plays an especially important role in the chemistry of the body, due in part to its propensity to form covalent bonds with itself and other molecules
• Elements can have multiple roles and exist in different states in the body
• Other important elements in the body

  • Fluorine (F)
  • Sodium (Na)
  • Magnesium (Mg)
  • Phosphorus (P)
  • Sulfur (S)
  • Chlorine (Cl)
  • Potassium (K)
  • Calcium (Ca)
  • Iron (Fe)
  • Iodine (I)
• Atom


  The smallest particle of an element that has the chemical characteristics of that element
• The characteristics of matter result from the structure, organization, and behavior of atoms
• Subatomic particles


  • Neutrons
  • Protons
  • Electrons
• Neutron


  No electric charge
• Proton


  One positive charge
• Electron


  One negative charge
• The positive charge of a proton is equal in magnitude to the negative charge of an electron
• The number of protons and the number of electrons in each atom are equal, and the individual charges cancel each other
• Each atom is electrically neutral
• Protons and neutrons form the nucleus at the center of an atom, and electrons move around the nucleus
• The nucleus accounts for 99.97% of an atom's mass but only 1 ten-trillionth of its volume
• Most of the volume of an atom is occupied by the electrons
• Atomic number


  The number of protons in the atoms of an element
• Mass number


  The number of protons plus the number of neutrons in each atom
• Isotope


  Two or more forms of the same element that have the same number of protons and electrons but a different number of neutrons
• Isotopes of hydrogen


  • Hydrogen
  • Deuterium
  • Tritium
• Isotopes can be denoted using the symbol of the element preceded by the mass number (number of protons and neutrons) of the isotope
• Atomic mass


  The average mass of an element's naturally occurring isotopes, taking into account the relative abundance of each isotope
• Individual atoms have very little mass
• Mole


  The SI unit for the amount of substance, containing as many elementary entities (atoms, molecules, or other particles) as there are atoms in exactly 12 g of the carbon-12 isotope
• The number of particles in a mole is known as Avogadro's number, approximately equal to 6.022 x 10^23
• Examples of moles


  • 1 mole Cu = 6.022 x 10^23 Cu atoms
  • 1 mole H2O = 6.022 x 10^23 water molecules
  • 1 mole NaCl = 6.022 x 10^23 sodium chloride formula units
• Molar mass


  The mass in grams of 1 mole of a substance, which is equal to its atomic mass units
• For any element the molar mass (grams) is numerically equal to the atomic mass (AMU)
• Chemical bonding


  Formed when electrons in the outermost energy level (valence shell) are either shared with or transferred to another atom
• Electron shells


  • Energy levels depicted as concentric rings
  • Outer shells do not contain electrons until the inner shells have reached their maximum
  • Valence shell: outermost shell
• Inert atoms


  If the valence level is full with eight electrons (called an octet), the atom is inert and does not form bonds with other atoms
• Reactive atoms


  If the valence shell is incomplete, the atom is chemically reactive and forms chemical bonds to achieve an octet
• Octet rule


  The tendency of atoms to combine with other atoms until each has 8 electrons (2 electrons for hydrogen) in its valence shell
• Electronegativity


  The ability of an atom's nucleus to attract electrons