Atomic & Molecular Orbitals (U2,c1/6)(U1,c2/7) Flashcards
What is the Principal Quantum number?
n - Main energy level - The size and energy of the shell
What is the Second Quantum number?
ℓ - Angular momentum - Shape of subshell (s, p, d, f)
What is the Third Quantum number?
m - Magnetic - Orientation in space of the orbital
What is the Fourth Quantum number?
s - Spin - Direction of spin
What are the values of n?
1, 2, 3, 4, etc.
What are the values of ℓ?
From 0 to (n-1)
What are the values of m?
Any whole number between -ℓ and +ℓ
What are the values of s?
+1/2 or -1/2
What is Heisenberg’s Uncertainty Principle?
That it is impossible to state precisely the position & momentum of an electron at the same instant.
What does it mean if orbitals are degenerate?
They have the same energy as each other.
What does the Aufbau Principle say?
The orbitals of the lowest energy levels are always filled first. (“aufbau” from German “building up”)
What does the Pauli Exclusion Principle say?
- An orbital cannot contain more than two elecrions, and 2. They must have opposite spin.
What does Hund’s Rule of Maximum Multiplicity say?
Where there are degenerate orbitals in a subshell, electrons fill each one singly, keeping spins parallel BEFORE spin pairing occurs.
What IS an orbital?
A region of space in which it is very certain that an electron will be found - (the region in which the electron lives)
How is a molecular orbital formed?
When the atomic, hybrid or other molecular orbitals merge to form a set of molecular orbitals.
What is the basis of bonding between atoms?
The attraction of positive nuclei to negative electrons occupying molecular orbitals.
What is the bonding molecular orbital?
The molecular orbital in which the electrons spend most of their time IN the region between the two nuclei.
What is the antibonding molecular orbital?
The molecular orbital in which the electrons spend most of their time AWAY FROM the region between the two nuclei.
How is a covalent bond formed? (in terms of orbitals)
Two half-filled atomic orbitals overlapping
How is a σ bond formed?
When the atomic orbitals overlap end-on // along the axis of the bond
How is a π bond formed?
When the atomic orbitals lie perpendicular to a σ bond overlap side-on
Which kind of bond is stronger - σ or π bonds?
σ bonds (end-on overlap)
How are σ and π bonds formed through hybridisation?
The 2s orbitals and three 2p orbitals combine during bonding to form FOUR new identical hybrid orbitals called sp3 orbitals.
What determines where a compound fits into the bonding continuum?
The difference in electronegativity between bonded atoms.
What determines the type of bonding in a molecule? (ionic, polar covalent, pure covalent)
The symmetry and the position of bonding orbitals between atoms.
