<p> ORGANIC CHEMISTRY</p><p>B.6 – CHEMICAL BONDING  Organic Chemistry  Used to be considered chemistry of living things (or things that were once living)  Chemistry of Carbon compounds  More than 90% of all known compounds contain Carbon (although it accounts for only 0.2% of the earth’s composition)  Over 6,000,000 organic compounds have been identified – and that number is increasing daily with the synthesis of new compounds in labs  Hydrocarbons : organic compounds containing only C and H atoms  Q: Why do atoms form compounds?</p><p> Electron shells : atoms like to have full shells  First shell holds 2 electrons  Second , and subsequent outer shells hold 8 electrons  Two major ways atoms can make compounds (fill their shells) :  IONIC compounds – involve IONS (+ or -)  Ex. – Sodium (Na) – draw the difference between a sodium atom and sodium ion (show protons, neutrons, and electrons in each)  Ex. – Flourine (F) – draw the difference between a flourine atom and flourine ion</p><p> MOLECULAR (COVALENT) compounds – involve sharing electrons – NO ions!!  Ex. – Hydrogen (H) – has 1 electron, would like to have 2 to fill the FIRST shell….</p><p> Electron dot formulas -  Show only the electrons in the outer shell (figure this out by looking at the group i.e. – Sodium (Na), in group 1, has 1 electron in outer shell….)</p><p> Ex. – show electron dot formulas for Mg, C, N, O</p><p> Structural Formulas –  Show the shared outer shell electrons as lines, representing bonds between atoms in a covalent compound</p><p> Ex. – Show structural formula for methane (CH4) </p><p> Molecular Formulas – show the number of atoms of each element, but NOT how they are arranged  Can be written short : CxHy (CnH2n+2 for alkanes) Can be written long : C6H14 = CH3CH2CH2CH2CH2CH3 </p>