This is a draft cheat sheet. It is a work in progress and is not finished yet.
The 4 Quantum Numbers
Principle Quantum Number |
Secondary Quantum Number |
Magnetic Quantum Number |
Spin Quantum Number |
n |
l |
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Electron Configurations
Electrons fill orbitals from lowest to highest energy. Therefore, orbital 1s fills before 2s and 2p. However, an orbit does not necessarily fill completely before the next begins. |
Types of Bonds
IONIC
- metals give electrons to non-metals
- metals form cations (+)
- non-metals form anions (-)
- this gives both atoms a stable electron configuration
- the energy level of each atom is decreased |
If attraction outweighs repulsion, then a bond will form |
Characteristics
- conductive in the dissolved or molten state
- solid, hard, brittle
- high melting point, low boiling point |
COVALENT BONDING
1. Non-polarequal sharing of electrons for bonds
2. Polarunequal sharing of electrons, atom with higher EN is slightly +, lower EN is slightly -
3. Coordinate Covalent Bonds- both electrons forming the bond come from the same atom |
Characteristics
- generally low boiling points
- solid, liquid, gas
- do not conduct electricity
- dull
- don't dissolve in water |
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Intermolecular Forces
An attraction holding neighbouring molecules or ions together. These are not bonds |
1. Ion-Ion whole charges attract |
2. Ion-Dipole an ion is attracted to a polar molecule. The cation is attracted to the slightly negative portion of polar molecules and the anion to the slightly positive end |
3. Dipole-Dipole the attraction between oppositely charged dipoles of 2 polar molecules
- strength depends on the polarity of the molecule (more polar=stronger dipole force)
- H-bonding is a special type which is the strongest (5% of covalent bond strength)
- H bonded to N, O, F
- a lone pair of electrons must be on the neighbouring molecule for the H to bond with
- strength depends on the number of H bonds |
4. Dipole-Induced Dipole- nonpolar molecule forced into polarity |
4. Induced Dipole-Induced Dipole a.k.a. London Dispersion Forces
- the random motion of electrons creates a temporary dipole in one nonpolar molecule. This induces polarity in the neighbouring molecule. Strength depends on # of electrons (and protons) in a molecule. |
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Types of Solids
Metallic Crystals (Metallic Bonding) |
- valence electrons from a mobile sea of electrons which comprise the metallic bond
- high melting and boiling points |
Ionic Crystals (Ionic Bonding) |
- attraction of charged ions for one another. Lattice energy is a measure of ionic strength
- high melting and boiling points |
Covalent Crystals (Network Covalent Bonding) |
- network solids are extremely hard compounds with very high melting and boiling points due to their endless 3-D network of covalent bonds |
Molecular Crystals a)H-bonding
b)LDF
c)Dipole-Dipole Forces |
a) H-bonds are weaker than covalent bonds, but stronger than b) or c) below
b) universal force of attraction between instantaneous dipoles. These forces are weak for small, low-molecular weight molecules, but large for heavy, long/highly polarizable molecules. They are stronger than c) below
c) these forces act between polar molecules. They are much weaker than H-bonding |
Atomic Crystals
(Dispersion Forces) |
- see section b) above |
Physical properties depend on these forces. The stronger the forces between particles,
- thethe melting and boiling point
- thethe vapour pressure
- the the viscosity
- the greater the surface tension
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