Download Tutorial 3 - answers • Complete the following table, giving either the

Tutorial 3 - answers
• Complete the following table, giving either the systematic name or the molecular
formula as required.
Formula
Systematic name
NaHSO4
Sodium hydrogensulfate
AsCl3
arsenic(III) chloride
CrCl3⋅6H2O
Chromium(III) chloride-6-water
Ag2Cr2O7
silver dichromate
• Complete the following table, providing the ground state electron configuration for each
of the following species.
Species
chlorine atom
Marks
2
3
Ground state electron configuration
1s2 2s22p6 3s23p5 or [Ne] 3s23p5
magnesium ion
1s2 2s22p6 or [Ne]
arsenic(V) ion
1s2 2s22p6 3s23p63d10 or [Ar] 3d10
• The diagram below shows the general trend for the first ionisation energy for some
s and p block elements.
1800
1600
1400
1200
kJ mol–1
1000
800
600
400
200
0
Na
Mg
Al
Si
P
S
Cl
Ar
How will the general trend differ for the second ionisation energy of these elements
(i.e. X+(g) → X2+(g) + e–)? Explain.
All second ionisations energies are > first ionisation energies as an electron is
being removed from an already positive ion.
The value for Na will be very high as the electron is taken from a core (n=2)
shell.
There will be a general increase in second ionisation energy from Mg to Ar.
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Tutorial 3 - answers
1.
Which of the following elements has the atom with the largest atomic radius?
A
B
C
D
E
2.
√
Which of the following elements has the greatest electronegativity?
A
B
C
D
E
3.
sulfur
chlorine
argon
potassium
calcium
sulfur
chlorine
argon
potassium
calcium
Marks
1
1
√
An isotonic solution is one that has the same osmotic pressure as cellular fluid.
Isotonic saline has a higher chloride ion concentration than intracellular fluid.
When cells are placed into an isotonic saline solution:
A
no exchange of water will occur across the cellular membranes.
B
there will be a net flow of chloride ions into the cells until the chloride ion
concentrations are equalised.
C
there will be a net flow of water out of the cells until the chloride ion
concentrations are equalised.
D
there will be a net flow of water into the cells until the chloride ion
concentrations are equalised.
E
water will enter the cells at the same rate that it leaves the cells. √
• Copper is an essential element in human biology, deficiencies leading to blood
disorders. Excess copper can occur in cases of poisoning or in Wilson’s disease.
Draw a graph showing the relationship between overall health and the level of copper
in the body and identify the ‘healthy’ range.
Describe one biological function of copper.
Copper enzymes are involved in electron transport systems due to the ability of
copper to change its oxidation state.
1
2
Tutorial 3 - answers
Challenge Questions
• State Hund’s rule and illustrate its application in the orbital box diagram of the
nitrogen atom.
Marks
2
Hund’s rule states that when filling orbitals of the same energy, there is the
maximum number of unpaired electron spins (or orbitals of the same energy are
filled singularly first before electrons are paired up).
N
1s
2s
2px 2py
↑↓
↑↓
↑
2pz
↑
↑
• The atomic radius decreases across a period and increases down a group within the
periodic table. Explain these observations.
2
Across a period, the effective nuclear charge increases but the electrons occupy the
same shell. The increase in attraction to the nucleus causes a decrease in the atomic
size.
Down a group, the outer electrons occupy shells with higher n quantum numbers with
large average orbits and the size increases.
• Each of the following electron configurations represents an atom in an excited state.
Identify the element and write its ground state electron configuration.
Electron configuration of
excited state
1s2 2s2 2p6 3s2 3p4 4s1
Element
Chlorine
Electron configuration of
ground state
1s2 2s2 2p6 3s2 3p5
or [Ne] 3s2 3p5
1s2 2s2 2p6 3s2 3p6 4s2 3d3
4p1
Chromium
1s2 2s2 2p6 3s2 3p6 4s1 3d5
or [Ar] 4s1 3d5
2