CHEM1902 Main Group Chemistry
Tutorial 1 - 2015
Prof Robert J. Lancashire
1. The most accurate definition of ionization energy is ?
a) the energy required to add an electron to an atom or ion,
b) the energy required for an atom or ion to form a bond,
c) the energy required to remove a proton from the nucleus of an
atom or ion,
and d) the energy required to remove an electron
from an atom or ion
2. The most accurate definition of the term "electron affinity"
a) the amount of energy released when an atom forms a bond,
b) the amount of energy released when an electron is lost from a
neutral atom to form a cation,
c) the amount of energy required for a neutral atom to form a
and d) the amount of energy released when an
electron is added to a neutral atom to form an anion
3. Place the following elements in order of
increasing electron affinity: Cl, Na, O, C.
a) Na, C, O, Cl,
b) Cl, O, C, Na,
c) Na, C, Cl, O,
and d) Na, O, C, Cl
4. Rank the following elements in order of
increasing atomic radius: Na, B, F, Br
a) Br < Na < B < F,
b) F < B < Br < Na,
c) B < F < Na < Br,
and d) F < B < Na < Br
5. The largest atomic radius for a neutral
element is expected for which of the following electron
a) [He] 2s2 2p3,
b) [Ne] 3s2 3p3,
c) [Ne] 3s2 3p5,
and d) [He] 2s2 2p5
6. Which of the following is expected to have the
smallest crystal ionic radius?
and d) Al3+
Short Answer Questions
1. Describe the contributions of de Chancourtois, Newlands and
Mendeleev to the development of the modern periodic table.
2. Calculate the effective nuclear charge for
i) an outer p electron in an oxygen atom and
ii) a 3d electron in a nickel atom
iii) a 4s electron in a nickel atom.
3. What is the main difference between electron
affinity and electronegativity?
4. Which do you predict to have the greater
electron affinity, Y or Y- ? Why?
5. Predict the type of bond that would form between elements with
χ = 2.5 and 4.0? (Pauling scale)
Would this bond be more or less polar than a N-H bond? Justify
6. Account for the general increase in
ionization energy across period 3.
7. Account for the dip in ionization energy that is observed from Mg to Al
and from P to S.
8. How might the ionization energy, electron affinity and
electronegativity affect the reactivity of the elements?
9. The molecules NH3 and NF3 have trigonal pyramidal
structures, and dipole moments of 1.47 and 0.24D respectively.
The values of χP(N), χP(H) and χP(F)
are 3.0, 2.2 and 4.0.
Explain the variation in the observed dipole moments and show the
direction of the dipoles.
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Copyright © 2015 by Robert John
Lancashire, all rights reserved.
Created and maintained by Prof. Robert J.
The Department of Chemistry, University of the West Indies,
Mona Campus, Kingston 7, Jamaica.
Created November 2014. Links checked and/or last
modified 26th January 2015.