Organic chem

• Exceptions to the octet rule

  • Hydrogen
  • Helium
  • Lithium
  • Beryllium
  • Boron
  • Expanded octets
  • Odd electron compounds
• Hydrogen


  Has one valence electron, only needs two electrons to complete its first energy level
• Helium


  Has two valence electrons, its outer shell is full
• Lithium


  Has three electrons but only one valence electron, loses that electron to have two valence electrons like helium
• Beryllium


  Loses two electrons in its outer shell to have the same configuration as helium
• Boron (BH3)


  Has three valence electrons, only needs six electrons to fill its outer shell
• Expanded octets


  Possible for elements in the third period past silicon and below, electrons can hybridize and fill d orbitals
• Odd electron compounds


  Compounds with an odd number of valence electrons
• Formal charges can be used to determine the best Lewis structure for compounds with expanded octets or odd numbers of electrons
• Everything is made of atoms. Yes, even you.
• Atoms


  Consist of a core and some electrons. The core is made of protons and neutrons.
• Elements


  Different elements are determined by the number of protons
• Elements


  • Water (Hydrogen and Oxygen)
  • Sodium
• Quantum mechanics tells us that atoms do not actually look like the simple model, they look more complex
• Electron shells


  The electrons in the outermost shell are called "valence electrons"
• Most of chemistry is really just the behaviour of valence electrons
• Every element is listed in the periodic table
• Periodic table


  Elements in the same column or "group" have the same number of valence electrons
• Valence electrons


  For the main groups, the number is just the group number from 1 to 8, except for helium which can only have 2
• Transition metals do not follow a simple pattern in the periodic table
• Elements with the same number of valence electrons


  Tend to show similar behaviour in chemical reactions
• Alkali metals


  • They have one valence electron, are shiny metals, are kind of soft, and do this sometimes
• Periodic table rows or "periods"


  Elements in the same row have the same number of shells, which increases from top to bottom
• Atomic mass


  Increases from left to right as each element gains a proton, an electron and some neutrons
• Isotopes


  Depending on the number of neutrons in the core, you get different isotopes of the same element, most of which are pretty unstable and fall apart, releasing ionizing radiation
• Ionizing radiation from unstable isotopes will kill you
• Charged atoms


  If an atom has the same amount of electrons as protons, it has no charge. If it has more, it has a negative charge, and if it has less, it has a positive charge. Charged atoms are called "ions", negative ions are "anions" and positive ions are "cations".
• Periodic table


  Provides information on the name, symbol, number of protons, and atomic mass of each element
• Periodic table regions


  Left of the semimetal line are metals, right are non-metals (mostly gases), and the line is the semimetals
• Molecules


  Two or more atoms bonded together
• Compounds


  Molecules made of at least two different elements
• Compounds often behave completely differently than the elements they're made of
• Compounds


  • Table salt (explosive metal + toxic gas)
• Molecular formula


  Represents the number of each atom in a molecule as a subscript
• Isomers


  Molecules with the same molecular formula but different structures
• Lewis-Dot-Structure


  Represents the valence electrons and bonds as dots and lines
• Atoms


  Want to achieve a state of lower energy, which is having a full outer shell of electrons, usually 8 or 2 for hydrogen and helium
• Covalent bond


  Sharing of electrons between atoms to achieve a full outer shell
• Electronegativity


  The strength of an atom's pull on shared electrons, increases from bottom left to top right on the periodic table
• Ionic bond


  Forms when the difference in electronegativity is greater than 1.7, with one atom losing an electron to become a cation and the other gaining an electron to become an anion