CAIE A-Level Chemistry AS 1 Atomic Structure Questions

Practise subatomic particles, isotopes, electron arrangements, ionisation energy and atomic or ionic radius using CAIE-style evidence.

Covered syllabus points

1.1 Particles in the atom and atomic radius 1.2 Isotopes 1.3 Electrons, energy levels and atomic orbitals 1.4 Ionisation energy

[Maximum number: 1]

The table shows the numbers of protons, neutrons and electrons in four different particles, W, X, Y, and Z.

Table for Question 1 — CAIE A-Level Chemistry AS

Which pair represents the atoms of two isotopes of the same element?

W and Y

W and Z

X and Y

X and Z

[Maximum number: 1]

Neutrons are passed through an electric field. The mass of one neutron relative to $\frac{1}{12}$ the mass of a ${ }^{12} \mathrm{C}$ atom and any deflection in the electric field is recorded.

Which row is correct?

mass of

neutron

behaviour of beam of

neutrons in an electric field

deflected

not deflected

[Maximum number: 10]

(a)

Define first ionisation energy.

[ 2 ]

(b)

Successive ionisation energies for element A are shown in Table 1.1.

Table 1.1

Use Table 1.1 to deduce the group of the Periodic Table that A belongs to. Explain your answer. Group

[ 1 ]

(c)

Across Period 3 there is a general trend for first ionisation energies to increase due to the increase in attraction between the nucleus and the outer electron.

Explain why the first ionisation energy of sulfur is less than the first ionisation energy of phosphorus.

[ 2 ]

(d)

In an $\mathrm{A} l^{2+}$ ion the nuclear attraction for the outer electron is stronger than in an atom of Na .

Compare the electronic structures of $\mathrm{A} l^{2+}$ and an atom of Na and explain why the third ionisation energy of aluminium is greater than the first ionisation energy of sodium.

[ 2 ]

M1 similarity in electronic structure / shielding of $\mathrm{Al}^{2+}$ and Na both remove electron from (3)s ${ }^{1}$ / single electron in (3)s (sub-level / orbital)

OR $\mathrm{Al}^{2+}$ and Na have same electronic configuration

OR shielding (of outer electron) is the same

M2 greater nuclear charge / number of protons

$\mathrm{Al} l^{(2+)}$ has greater nuclear charge

OR 13p compared to 11p

(e)

An isotope of copper has a relative isotopic mass of 65 .

Complete Table 1.2 for an atom of copper-65.

Table 1.2

[ 3 ]

Correct completed table:

isotope	atomic number	nucleon number	number of neutrons	electronic arrangement
copper-65	29	65	65-29=36	$1\mathrm{s}^{2}2\mathrm{s}^{2}2\mathrm{p}^{6}3\mathrm{s}^{2}3\mathrm{p}^{6}3\mathrm{d}^{10}4\mathrm{s}^{1}$

M1: 29 and 65.
M2: nucleon number - atomic number;
allow ECF from M1.
M3: electronic arrangement.

[Maximum number: 5]

Vanadium, niobium and tantalum are metals in the same group of the Periodic Table.

(a)

The shorthand electronic configuration of vanadium in the ground state is $[\mathrm{Ar}] 3 \mathrm{~d}^{3} 4 \mathrm{~s}^{2}$ .

[ 3 ]

(i)

State what is meant by the term ground state.

[ 1 ]

(ii)

Show the electronic configuration of vanadium using electrons in boxes notation.

Figure for Question (ii) — CAIE A-Level Chemistry AS

[ 1 ]

(iii)

Deduce the total number of electrons in the p sub-shells of a vanadium atom.

[ 1 ]

(b)

Pelopium was the suggested name for a new element discovered in a mineral.

Pelopium was later found to be a mixture of niobium, Nb , and tantalum, Ta .
Only one naturally occurring isotope exists for each of Nb and Ta .

[ 2 ]

(i)

Complete Table 1.1.

Table 1.1

[ 2 ]

isotope & RIM & \# protons & \# neutrons

${ }_{41}^{93} \mathrm{Nb}$ & 92.91 & $\bullet 41$ & $\bullet 52$ ${ }_{73}^{181} \mathrm{Ta}$ & 180.95 & $\bullet 73$ & $\bullet 108$

All question bank results loaded

Covered syllabus points

Question 1

Question 2

Question 3

Question (a)

Question (b)

Question (c)

Question (d)

Question (e)

Question 4

Question (a)

Question (i)

Question (ii)

Question (iii)

Question (b)

Question (i)