ORCHEM Midterm PDF

ORCHEM Definition of Terms 1. Valence Bond Theory – covalent bonds forms when 2 atoms come close together and a single occupied orbital form one atoms overlaps with a sing occupied orbital from the other atom. 2. Hybridization – mixture of orbitals at the same energy level. Shows the molecular geome...

ORCHEM Definition of Terms 1. Valence Bond Theory – covalent bonds forms when 2 atoms come close together and a single occupied orbital form one atoms overlaps with a sing occupied orbital from the other atom. 2. Hybridization – mixture of orbitals at the same energy level. Shows the molecular geometry and bonding of the atomic orbitals Sigma bonds – formed by HEAD TO HEAD overlapping Pi Bonds – formed by SIDEWAYS overlapping sp^3 hybrid orbitals - s+p+p+p - 25%s and 75% p - Four sp^3 hybridized orbitals - Bond angle: 109.5 degrees - Bond length: 109 pm Sp^2 hybrid orbitals - s+p+p - 33% s and 67% p - 3 sp2 hybridized and one unhybridized orbital - Bond angle: 121.3 degrees x 117.4 degrees - Bond length: 108.7 pm x 134 pm Sp Hybrid orbital - s+p - 50% s and p - 2 sp hybridized and 2 unhybridized orbitals - Angle: 180 degrees  Molecular Bond Theory - A covalent bond forms from mathematical combination of atomic orbitals, wave function, on different atoms to form molecular orbitals 2 ways for orbital combination to occur - ADDITIVE COMBINATION – bonding molecular orbit; leads to formation of MO that is lower in energy and roughly egg-shaped - SUBTRACTIVE COMBINATION – antibonding molecular orbit; leads to a formation of MO that is HIGHER in energy and has anode between nuclei (elongated dumbbell shape) PROPERTIES OF COVALENT BONDS - 1. BOND POLARITY - refers to the distribution of electric charge across a chemical bond between two atoms. - Factors affecting the bond polarity: a) Effect of electronegativity bonding elements b) Effect of the orbital electronegativity of bonding elements c) Effect of influence of neighboring atoms 2. BOND LENGTH - the distance between the centers of two covalently bonded atoms 3. BOND STRENGTH – force holding different materials or atoms together. Measures the amount of energy needed to break different types of bonds ORDER OF STRENGTH : IONIC BOND > COVALENT > HYDROGEN 4. BOND ORDER – number of bonding pairs of 2 electrons between 2 atoms  CHEMICAL STRUCTURES 1. Lewis structure 2. Structural Formula 3. Simplified structural formula 4. Condensed structure 5. Skeletal/Line structure 1. Lewis Structure – electron-dot structures, valence shell electrons are represented as DOTS 2. Kekule Structure – simpler than Lewis structure, line bond structure, 2 electron covalent bonds are indicated as lines drawn between atoms 3. Structural structure - a illustrates the arrangement of atoms in a molecule based on their bonding sequence. It also shows the types of bonds between the atoms, such as single, double, or triple covalent bonds. 4. Condensed structure - Shows the molecular entities in which atoms of the molecule are shown without a bond 4. Skeletal structure - Shows molecular entities in which bonds between atoms are shown without actual atoms.