( 1 ) Orbitals and Bonding

Question 1

Quantum Numbers

Answer 1

• Represented by the symbols n, l, m, s
• First two numbers correspond to the orbital

Question 2

First quantum number

Answer 2

• Symbol: n
• Related to the distance of the electron from the nucleus therefore to the energy of the electron
• The greater the value of n, the greater the average distance of the electron from the nucleus and the greater the electron’s energy
• Determines the row occupied by the atom in the periodic table

Question 3

Second Quantum Number

Answer 3

• Symbol: l
• Related to the shape of the orbital (each value of l signifies a different orbital shape) and depends on the value of n (l = n-1) l = 0, spherical l = 1, p orbital l = 2, d orbital l = 3, f orbital

Question 4

Third Quantum Number

Answer 4

• Symbol: m
• m depends on l m = -l….0….+l
• m is related to the orientation of the orbital in space
• Orbitals of the same shell (n) and the same shape (l) are at the same energy regardless of the m₁ value

Question 5

Spin Quantum Number

Answer 5

• Symbol: s
• Only has the two values ±1/2

Question 6

Paired Spins

Answer 6

• Two electrons having opposite spins

Question 7

Unpaired Spins

Answer 7

• Two electrons having the same spin

Question 8

Pauli Principle

Answer 8

No two electrons may have the same vlues of the four quantum numbers.

Question 9

Aufbau Principle

Answer 9

Assumes that we should fill the available orbitals in order of their energies, starting with the lowest-energy orbital.

Question 10

Hund’s Rule

Answer 10

For a given electron configuration, the state with the greatest number of unpaired (parallel) spins has the lowest energy.

Question 11

Energy Levels of sp³ Orbitals

Answer 11

sp³ orbitals are lower in energy than 2p, but higher than 2s orbitals

Question 12

Functional Group

Answer 12

A collection of atoms that behave the same wherever they appear in a molecule.

Question 13

Resonance Forms

Answer 13

• Different electronic representations of the same molecule.
• Only differences allowed in a set of resonance forms are differences in electron distribution
  
  • There can be no change in the position of the atoms in resonance form.

Question 14

Resonance Arrow

Answer 14

Double-headed arrow between resonance forms

Question 15

Electron Pushing

Answer 15

• Use of curved arrows to show how electrons move from one point to another.
• The curved arrow always runs from the pair of electrons (l.p. or a bond), never to a pair of electrons.

Question 16

Bonding Molecular Orbital

Answer 16

An MO that is the result of mixing atomic orbitals that are in phase with each other.

Question 17

Non-bonding Orbital