U2 - Module 2: Looking for Patterns Flashcards
(61 cards)
What is the structure of a molecule determined by?
- Atomic composition
- Atom connectivity
Why is understanding the molecular structure important?
Molecules can have the same number of each atom (structure), but different formulas.
What part of an atom is positive charged and which is negative charged?
Positive: Nucleus; protons
Negative: Electron Cloud; electrons
Electrostatic Model
The formation of covalent bonds is induced by a net attraction force between electrons and protons in different atoms.
What happens when atoms come too close together?
Repulsion forces take over
Bond strength
Energy needed to move two atoms apart (break bond)
Bond length
Sweet spot of atom distance (attractive = repulsion)
What happens to the potential energy when atoms move closer and further apart?
Closer: Decreases
Farther: Increases
Quantum Model
Explains more detail about covalent bonding
Electron Density
The measure of probabilities for atoms to bond
What does a higher electron density correlate to?
A higher probability of atoms bonding since more electrons are present.
Electron Delocalization
Energy decreases when forming a covalent bond.
What happens as a net result of electron delocalization?
The total energy goes down
What is delocalization doing to the atoms?
Stabilizing
- decreases potential energy
What does it take more energy to break?
Multiple bonds compared to a single bond
What does the frequency of atoms depend on?
- Strength of the force between atoms
- Their masses
What spectrum does atomic vibration occur in?
Infrared
Wavenumber formula
1/wavelength
What is the wavenumber directly proportional to?
The frequency and energy level
What happens if the exact frequency/wavelength isn’t applied?
The electrons will not change vibrational state.
What is low transmittance directly proportional to?
high absorbance
How is weight proportional to wavenumber?
The higher the wavenumber, the lighter the mass.
Do atoms with low or high wavenumbers have stronger bonds?
Higher wavenumbers
Higher energy
X Ray Radiation
Measures the distance between atoms