Class 2: Bonding, Intramolecular Forces, Thermodynamics Flashcards
(31 cards)
Define formal charge
the charge assigned to each atom in a molecule (valence e - 1/2 bonding e - free e)
What determines hybridization of a molecule
Sets of electrons
What determines orbital geometry in a molecule
groups of electrons
What determines molecular geometry / shape
Lone pairs of electrons on central atom
What makes a bond stronger?
More electrons shared or a shorter distance between atoms
What determines the polarity of a bond?
Difference in electronegativity between atoms
Define ionic bonds
bonds between particles of opposite charges where the e- are located on the ions
Properties of ionic bonds
Brittle, insulators
Define covalent bonds
Bond between atoms with high electronegativity where electrons are shared and dipoles are created
Properties of covalent bonds
insulating, rigid
Define metalic bonds
Bonds between atoms with low electronegativity where electrons are delocalized among all atoms
Define coordinate covalent bonds
Bonds between atoms with lone pairs and e- deficient species where e- are localized between atoms and e- are donated from nucleophiles
Properties of coordinate covalent bonds
Easily dissociated
Define dispersion forces
induced dipole-dipole forces produced by collisions that make temporary but small dipoles formed by electron cloud deformation
Properties of dispersion forces
Weak and easily cleaved
Define hydrogen bonding
Formed between very polar forces; force aligned along permanent bond dipole
Properties of hydrogen bonding
strongest of Van der Waals forces
Define Van der Waals forces
Weak short-range electrostatic attractive forces between uncharge molecules arising from interaction of permanent or transient electric dipole moments
Define enthalpy
energy stored within chemical bonds or any attractive force (delta H)
Define Hess’s law of summation
Adding together known changes of enthalpy to mathematically determine enthalpy changes for a different reaction
Define entropy
(S)
Potential randomness
How does entropy increase (3)
1) increasing the number of particles
2) increasing the volume
3) increasing temperature
Define Gibb’s free energy
(G) energy available to do work;
What does free energy tell you
Energy available to do work; if a reaction will be spontaneous or not
