Download Answers to Critical Thinking Questions 4

Worksheet 4 – Answers to Critical Thinking Questions
The worksheets are available in the tutorials and form an integral part of the learning
outcomes and experience for this unit.
Model 1: Light and Waves
λ +
+
+
+
+
+
+
+
* *- * *- * *- * *- * *- * *- * *- * *
A
λ 1.
See figure.
2.
See figure.
3.
See figure. Negative regions shaded light grey.
4.
Square shown in red.
Model 2: Electron Waves
-
+
wave
5.
See figure.
6.
See figure.
square
Model 3: Atomic Orbitals and Quantum Numbers
1. s orbitals consist of spherical shells (“lobes”). p orbitals consist of dumbbell
shaped along one axis. d orbitals consist of four leaved “flower” shapes.
2. The angular momentum quantum number, l.
3.
4.
n
Possible l values
Orbital labels
1
0
s
2
0 and 1
s and p respectively
3
0, 1 and 2
s, p and d respectively
l
Possible ml values
Orbital labels
1
1, 0, -1
3 × p {px, py, pz}
2
2, 1, 0, -1, -2
5 × d {dxy, dxz, dyz, dz2, dx2-y2}
3
3, 2, 1, 0, -1, -2, -3
7×f
5. s orbitals have no nodal planes. p orbitals have one nodal plane. d orbitals have
two nodal planes.
6. The number of nodal planes is equal to the value of the angular momentum
quantum number, l.
The 2s has one radial node and the 3s has two radial nodes. 3p have one radial
node. In general, the number of radial nodes is equal to n – l - 1.
Model 4: Electronic Configurations in Atoms
1.
a. The Aufbau principle: Orbitals are filled with electrons in order of energy with
the lowest energy orbital being filled first.
b. Pauli Exclusion Principle: no two electrons may have the same set of quantum
numbers. No orbital can accommodate more than 2 electrons.
c. Hund’s Rule: in a set of orbitals with the same energy, electrons go into
different orbitals with aligned spins until each orbital in the set contains one
electron.
2
.
See figure.
a. The Pauli exclusion principle means that
a maximum of two electrons can occupy
an s orbital.
The electron configuration of carbon 1s2
2s3 2p1 has three electrons in 2s.
b.
Hund’s rule means that the three 2p
orbitals must each be occupied before
electrons can pair up.
The configuaion 1s2 2s2 2px2 has two
electrons spin-paired in 2px with the 2py
and 2pz empty.
200
100
0
2p
2s
-100
-200
-300
-400
-500
1s
-600