Chemistry (Bonding and Reactions) Flashcards
Lewis Structures
Diagrams representing structure of atoms.
- Count total valence electrons (VE)
- Fill octets
Formal charge
Method to determine whether a compound has a net charge on it and which atom is carrying the charge.
Resonance Structures
Multiple possible Lewis Structures
- Bond connectivity
- Delocalized electrons
a. Stabilizes compound to become less reactive.
Ionic Bonding
- Electrons transferred from one atom to another.
- Electronegativity difference (>1.7)
- Physical properties:
a. Very high melting and boiling point.
b. Liquid state conducts electricity.
Covalent Bonding
- Electrons shared between atoms.
- Electronegativity difference (<1.7)
- Physical properties:
a. Melting + boiling points lower than ionic compounds.
Bond order
- Single, longest, 1 sigma, weakest.
- Double, medium, 1 sigma + 1 pi, medium.
- Triple, shortest, 1 sigma + 2 pi, strongest.
Polar covalent bond
- Electrons shared unequally among atoms.
- Electronegativity difference (0.4 to 1.7)
- Dipoles
a. p (dipole moment)= q (charge) * r (charge separation). - Physical properties:
a. Melting + boiling points lower than ionic but greater than non-polar compounds.
Non-Polar Covalent bond
- Electrons shared equally between atoms.
- Electronegativity difference of elements (< 0.4)
a. diatomics: N2, O2
b. alkanes - Physical Properties:
a. Melting + boiling points lower than polar compounds.
Coordinate Covalent Bond
- Electrons shared between atoms.
- Both electrons donated by one of the atoms.
- Physical properties:
a. hybridized characteristics of both ionic and Covalent compounds.
London Dispersion Forces
- Weakest.
- Induced dipole.
- Size dependent.
a. More electrons makes it easier to polarize.
Dipole-Dipole
- Medium.
- Polar molecules.
- Strongest in liquid and solid.
Hydrogen Bonding
- Strongest.
2. H bonded to F, O and N.
Linear
180° sp 2 bonds 0 lone pairs e.g CO2
Trigonal Planar
120° sp2 3 bonds 0 lone pairs e.g CH2O
Bent
104.5 ° sp3 2 bonds 1 or 2 lone pairs e.g H20
Trigonal Pyramidal
107.5 ° sp3 3 bonds 1 lone pair e.g NH3
Tetrahedral
109.5 ° sp3 4 bonds 0 lone pairs e.g CH4
T-shaped
90 ° and 180 ° sp3d 3 bonds 2 lone pairs e.g ClF3
Seasaw
120 ° and 180 ° sp3d 4 bonds 1 lone pair e.g SF4
Trigonal Bipyramidal
90 ° and 120 ° sp3d 5 bonds 0 lone pairs e.g PF5
Octahedral
90
Empirical and Molecular formula
Empirical: simplest whole # ratio of elements in a compound.
Molecular: actual # of atoms in each element in a compound.
Equivalents
# of moles of a particular atom in a mole of a compound a. Usually refers to hydrogens in acid e.g HCl has 1 equivalent of Hydrogen
Percent composition
By Mass: grams of x/ grams total
By Mole: moles of x/ moles total