Chemlec

• Organic chemistry


  The study of the compounds of carbon (C)
• Over 30 million organic compounds have been identified
• About 1000 new organic compounds are discovered or synthesized and identified each day
• Carbon (C)


  A small atom that can share 4 valence electrons and form 4 covalent bonds, bond to one another to form long chains and rings, and form a diverse range of compounds from methane to DNA
• Atomic structure


  Small dense nucleus made of neutrons and positively-charged protons, with most of the mass contained in the nucleus, surrounded by extranuclear space containing negatively-charged electrons
• Orbitals


  Regions of space around a nucleus where electrons are found, with different kinds denoted as s, p, d, f, and each orbital can be occupied by 2 electrons
• Electron Configuration of Atoms

  The lowest-energy arrangement of an atom's electrons in orbitals, following rules for filling orbitals and accommodating electrons
• Valence shell is the outermost electron shell of an atom, and valence electrons are used in forming chemical bonds
• Lewis Structure


  The symbol of an element surrounded by a number of dots equal to the number of electrons in the valence (outermost) shell of the atom
• The Nature of Chemical Bonds

  Atoms bond to acquire the electron configuration of the noble-gas closest in atomic number, following the octet rule to achieve an outer shell of eight valence electrons
• Ionic bond


  A chemical bond resulting from the electrostatic attraction of an anion and a cation
• Atoms bond together


  So that each atom in the bond acquires the electron configuration of the noble gas closest in atomic number
• Octet rule


  The tendency to react in ways that achieve an outer shell of eight valence electrons
• An atom that gains electrons

  Becomes an anion
• An atom that loses electrons

  Becomes a cation
• Covalent bond


  A chemical bond resulting from two atoms sharing one or more pairs of electrons
• Forming Covalent Bonds


  A covalent bond forms when two atoms approach each other closely and a singly occupied orbital on one atom overlaps a singly occupied orbital on the other. The electrons are now paired in the overlapping orbitals and are attracted to the nuclei of both atoms, thereby bonding the atoms together
• Why a C-H bond (109 pm) is longer than an H-H bond (74 pm)
• Hybridization


  sp3 Orbitals and the Structure of Methane: Carbon has four electrons in its valence shell. An s orbital and three p orbitals can combine to form four equivalent atomic orbitals (sp3 hybrids) with tetrahedral orientation
• Polar Covalent Bonds


  Electronegativity: A molecule is polar if it has polar bonds and the center of partial positive charge lies at a different place within the molecule than the center of partial negative charge. Electronegativity is a measure of the force of an atom's attraction for the electrons it shares in a chemical bond with another atom
• Acids and Bases: The Bronsted-Lowry Definition

  HA + H2O ⇌ A- + H3O+. Ka = [A-] + [H3O+] / [HA]. pKa = -logKa
• Organic Acids and Organic Bases: Carboxylic acids
• Acids and Bases: The Lewis Definition

  A Lewis acid is a substance that has a vacant valence orbital and can accept an electron pair. A Lewis base is a substance that donates an electron pair. The donated pair of electrons is shared between Lewis acid and base in a newly formed covalent bond