CHEM

• Organic compound were derived from living organism (plants & animals)
• Inorganic compound were derived from non-living organism (miniral & gases)
• Friedrich Wohler explains the conversion of inorganic salt into urea(organic compound find in urine)
• Isomers- different compounds that have similar molecular formula
• August kekule, Archibad Scott Couper, and Alexander M. Butlerov define substances as specific arrangements of atoms
• Constitutional isomers - different compound that have the same molecular formula but different structural formula or sequence of atoms bonded
• Lewis Ans Kossel explain the nature of chemical bonds
• Ionic ( electrovalent)- bond formed by transferring one or more elctron to another to create ion
• Covalent bond - the result when atoms share electrons to achieve the configuration of noble gas
• Octet Rule- achieved configuration when the valence shell contains 8 electrons
• Molecules- composed of atoms joined exclusively or predominantly by covalent bond
• Lewis Structure - A diagram that shows the bonding between the atoms in a molecule using the valence electron of the atoms involved
• negative ion means we add one electron
• positive ion ( cation )- subtract one electron for each cation
• Formal charge- the amount of electron in a specific form of an atom in a molecule, it only applies for covalent bond
• Resonance theory - states that whenever a molecular or ion can be represented by two or more lewis structure that differ only in the position of the electron
• 1s orbitals have the lowest energy since they are near the positive nucleus next is the 2s orbitals
• Three 2p orbitals have equal but higher energy than 2s
• degenerate orbitals - orbitals that have the same energy but different shapes like three 2p orbitals
• Aufbau principle - "building up" - orbital are filled so that lowest orbitals are filled first
• Pauli Exclusion Principle - maximum of two electron are place in each orbital if the spin of the electron is paired.
• Hund's rule - electrons in a molecule are arranged in a regular pattern around the nucleus
• Hybridization - concept of mixing two atomic orbitals to give rise to a new type of hybridized orbitals
• SP3 hybridization

  • 2s electron is promoted into 2p orbitals
  • 109 degree bond angles making if a perfect tetrahedron
  • 2s orbitals and three 2p orbitals
  • four orbitals - 1 S orbitals and 3 P orbitals
• Double bond/2sp hybridization

  • two of the three p orbitals
  • result of mathematical operation is a carbon
• Triple bond/SP hybridization

  • one s orbital is mathematically averaged with one p orbital
  • has 2 sp orbitals and two p orbitals
• Single bond - one bonding interaction(1 σ)

  Double bond - two bonding interaction (1 σ and 1 pi)

  triple bond - three bonding interaction (1 σ and 2 pi)

  • triple bond → double bond → single bond
• Valence Shell Electron Pair Repulsion Theory (VSEPR) is a model that explains and predicts the shape of molecules or the molecular geometry
• Tetrahedron geometry

  • 4 bonded pairs of electrons, 0 lone pairs.
  • methane (CH4)
  • 4 hydrogen atom/electron pair will be positioned in four corners
  • SP3 hybridization
  • angle of 109.5°
• Trigonal pyramidal geometry

  • ammonia (NH3) (3 σ bond and 1 lone pair)
  • Nitrogen atom is SP3 hybridized and lone pair occupies it
• Trigonal Pyramidal

  • 107 °
  • ignored the lone pair
  • trigonal - nitrogen atom is connected to 3 other atoms
  • pyramidal- compound is shaped like pyramid with nitrogen above
• Bent Geometry

  • oxygen atom has 2 σ and 2 lone pair
• Trigonal Plana Geometry

  • SP2 hybridized
  • 120°
  • trigonal - boron atom connected to 3 other atoms
  • planar - all atoms lies in same plane
• Linear geometry

  • SP hybridization
  • beryllium has 2 valence electron
  • 2 hybridized orbitals
• Dipole moments and molecular polarity - negative and positive charge are separated by certain distance
• Molecular dipole moment- "vectur sum" - takes account both the magnitude and the direction of each individual dipole moment
• Carbon

  • sharing of 4 valence electron requires the 4 covalent bond
  • member of group 6 in the periodic table.
• HYDROCARBON- contains only a carbon (C) and hydrogen (H) atom
• HYDROCARBON DERIVATIVES - compound that consist a carbon, hydrogen, and one or more additional elements
• 2 classes of hydrocarbon - saturated and unsaturated