Organic Chemistry

ORGANIC CHEMISTRY

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?

• 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

• MOLECULAR (COVALENT) compounds – involve sharing electrons – NO ions!!
• Ex. – Hydrogen (H) – has 1 electron, would like to have 2 to fill the FIRST shell….

• 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….)

• Ex. – show electron dot formulas for Mg, C, N, O

• Structural Formulas –
• Show the shared outer shell electrons as lines, representing bonds between atoms in a covalent compound

• Ex. – Show structural formula for methane (CH4)

• 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