SCH4U1 Unit 1 Review

All the fun stuff 🤓🧪

Erwin Schrödinger

Erwin Schrödinger

Developed a series of mathematical equations to describe the motion of electrons in atoms.

Louis de Broglie

Had the idea that electrons have wave properties. Suggested that an electron bound to a nucleus in an atom resembled a standing wave.

Werner Heisenberg

Created Heisenberg’s Uncertainty Principle

Ferromagnetism

The ability of some atoms to form a permanent magnet (keeping their electron spins in the same direction even after an electric field is removed).

Paramagnetism

The weak attraction of a substance to a magnetic source. This term usually applies to individual atoms.

Hund’s rule

Electrons must be spread out amongst orbitals in such a way that as many electrons as possible remain unpaired.

Pauli Exclusion Principle

No two electrons in the same atom can have the same quantum numbers. This leads to the fact that orbitals can hold a max of 2 electrons.

Aufbau principle

Each electron added will occupy the lowest available energy level.

Heisenberg’s Uncertainty Principle

It is impossible to know the exact location and momentum/speed of an electron at a given moment.

Quantum Mechanical Model

Determines the allowed energies an electron can have, and only shows where electrons are likely to be.

Wave function

A mathematical description of an orbital, describing where an electron of a given energy is likely to be found.

Electron probability density

A plot indicating regions around the nucleus where electrons are likely to be found.

Orbits:

• Set path

• #E^- = 2n² (n = energy level)

• 2D

• Fixed distance from nucleus

Orbitals:

• No set path

• Max #e^- = 2

• 3D

• Distance from nucleus varies

Difference between orbits and orbitals?

Isoelectronic

Having the same number of electrons per atom, ion, or molecule.

Order of geometries for a tetrahedral orientation?

tetrahedral (109.5), trigonal pyramidal (107), bent (104.5)

Order of geometries for a trigonal bipyramidal orientation?

trigonal bipyramidal (120, 90), seesaw (180, 120, 90), t-shaped (180, 90), linear (180)

Order of geometries for an octahedral orientation?

Octahedral (90), square pyramidal (90), square planar (90), t-shaped (180, 90), linear (180)

Order of geometries for a trigonal planar orientation?

Trigonal planar (120), bent (120), NA

Electron correlation problem

Impossible to calculate exact repulsions between electrons

VSEPR

Valence Shell Electron-Pair Repulsion Theory

What does “A” represent in VSEPR Theory?

Number of central atoms

What does “X” represent in VSEPR Theory?

Number of bonding electrons on central atom

What does “E” represent in VSEPR Theory?

Number of lone pairs on central atom

Electronegativity

How strongly an atom attracts a pair of bonding electrons when in a covalent bond

ENC

Effective nuclear charge. Attraction of the nucleus to a valence electron of interest.

ES

Electron shielding. The blocking of ENC due to inner-shell electrons.

Valence bond theory

Half-filled atomic orbitals overlap to form a new orbital with a pair of opposite-spin electrons.

Hybrid orbital

An orbital created from the combination of at least 2 different orbitals

Hybridization

The process of forming hybrid orbitals from at least 2 different orbitals

Ionic crystals

• Crystal lattice structure

• Alternating (+) and (-) charges

• Hard & brittle

• High MP

• Conducts electricity in solution

Metallic crystals

• Electrostatic interactions

• Electron sea theory

• Hard

• Sheen

• Malleability

• High MP/BP

• Electrical conductivity

• Low IE

Molecular crystals

• Individual molecules held together by intermolecular forces

• IMFs determine structure and properties

Covalent network crystals

• Intramolecular forces = woven network

• Extreme hardness

• High MP/BP

• Diamond, graphite, buckyball/fullerene, carbon nanotube

Diamond

Interlocking tetrahedral structure

Graphite

• Hexagonal sheet

• Slippery & black

• Electrical conductor

Buckyball/fullerene

• Soccer-ball like structure

Carbon nanotubes

• Structure similar to buckyballs

• Cylindrical

Semiconductors

Covalent network crystal, conducts electricity a little at room temperature, increases conductivity with temperature

• Si, Ge

Doping

Modifying semiconductors to make them have specific conductive properties

Electrostatic interactions

Interactions between opposite electric charges.