82928756 Atomic Structure Tutorial

JC1 H2 Chemistry
Atomic Structure Tutorial

1. How many protons, neutrons and electrons are there in 3+ ion?
2. Write down the electronic configuration of
(a) Si (atomic no. 14)
(b) Sc (atomic no. 21)
(c) Co (atomic no. 27)
3. Which of the following ions contains an unpaired electron?
A calcium ion
B copper(II) ion
C potassium ion
D titanium(IV) ion
4. Some isotopes are unstable and decompose naturally. In one type of decomposition, a neutron in the nucleus decomposes to form a proton, which is retained in the nucleus, and an electron, which is expelled from the atom.
Which change describes a process of this sort?
A 11C  12C
B 22Na  22Ne
C 32P  31P
D 40K  40Ca
5. How many electron pairs, with principal quantum number n = 3, can be accommodated in an atom?
A 6
B 9
C 14
D 18

6. The first ionisation energies, in kJ mol-1, of Group II and III elements are given below: Group II Group III
Be 900 B 799
Mg 736 Al 577
Ca 590 Ga 578

(a) Define, by means of an equation, what is meant by the first ionisation energy of an element.
(b) Explain why the first ionisation energies decrease in magnitude on descending Group II.
(c) Explain why the first ionisation energy of aluminium is less than that of magnesium
(d) Suggest why the first ionisation energies for gallium is slightly higher than that of aluminium.

7(a) What are the electronic configurations of a calcium atom and a calcium ion?

(b) Why is the atomic radius of calcium significantly larger than the ionic radius of calcium?

8. Consider two ions: 3- and - where V and W represent two elements.

(a) When a beam of the above ions is passed through an electric field, which direction would they be deflected?

(b) Which ion would be deflected more in the electric field? Briefly explain your answer.

9. Why is the first ionisation energy of Neon higher than that of Sodium?

10. An element X has the following first eight ionisation energies: 703, 1610, 2460, 4350. 5400, 8500, 10300 and 12300 kJ mol-1

To which group in the Periodic Table does X belong? Give your reasoning.

11. What is the electronic configuration of the atom of the element which is isoelectronic (with the same number of electrons) with H2S?
12. What kind of orbital must an electron with the principal quantum number n = 3 occupy?
A a spherically-shaped orbital
B either a s, p or d orbital
C a dumb-bell shaped orbital
D a 3f orbital
13. The following ideas were those underlying John Dalton’s atomic theory, published in 1803.
Which idea is known to be correct?
A Atoms are indivisible.
B Atoms are very small.
C Atoms of an element are identical.
D Atoms of one element always differ in mass from those of another element.
14. Which factor explain why the value of the first ionisation energy of sulfur is lower than that of phosphorus?
A repulsion between the pair of 3p electrons
B greater shielding by inner electrons of sulfur
C increase of principal quantum number of sulfur compared to phosphorus
D increase in the effective nuclear charge of sulfur compared to phosphorus