UNIT 2.2 INTRAMOLECULAR FORCE AND POTENTIAL ENERGY

Chemistry is the study of matter and interactions. Chemistry overlaps with many other sciences.

Below is the contents for this sub unit.

INTRAMOLECULAR FORCE AND POTENTIAL ENERGY

The graph above plots potential energy vs. atom distance for covalent bond. Remember the atoms are sharing electrons, so they want to be close enough to share.

Left: atoms are too close, energy is high pushing each other away

Right: Atoms too far away from each other feel 0 attraction or repulsion

Lowest point: Covalent bonds try to maintain the lowest energy so this is the distance the atoms maintain. This also shows the bond energy (if numbers were on the left side).

Factors that effect the distance of a covalent bond:

Size of atom's core

Bond order (single, double, or triple bond)

Higher order (double and triple) have shorter bond length and larger bond energies.

REVIEW COULOMB'S LAW (IONIC BONDS)

Coulomb's law is used to calculate the force between two charged particles (ionic bonds), so in ionic bonds, one particle has a positive charge and one has a negative and they form a lattice.

F (is proportional to) q1 x q2 / r^2

F is the force. q1 and q2 are the charge on the 2 particles. r is radius (which is squared).

So looking at the formula, larger charges produce stronger forces

Also the smaller the ions (radius decrease) the more force there is.

SO: A ionic bond that has small particles with strong charges is hard to pull apart.