IB Chemistry 3.1 The periodic table Questions

IB Chemistry syllabusChemistry SL/HLFirst assessment 2025

Use periodic table position to classify elements, explain ionization-energy changes with shell and subshell arguments, and deduce simple redox outcomes.

Exam points

identify block, group or element type from periodic-table position, electron configuration or IE data
explain first IE trends using distance, shielding, nuclear charge, and the Be to B s-to-p subshell drop
deduce halogen displacement equations, oxidation states and colour change, e.g. Br2 + 2I- -> 2Br- + I2

[Maximum number: 5]

The graph shows the variation of the first ionization energy with atomic radius for periods 2, 3 and 4 of the periodic table, with the d-block elements omitted.

(a)

Annotate the graph with an additional data point, marked with a cross ( X ), for scandium. Use sections 9 and 10 of the data booklet.

[ 1 ]

(b)

Suggest why there might be a link between the two variables in the graph.

[ 1 ]

(c)

The graph shows a relationship between first ionization energy and atomic radius.

[ 3 ]

(i)

State the type of relationship between the variables.

[ 1 ]

(ii)

Compare and contrast the trends shown by the different periods.

[ 2 ]

[Maximum number: 1]

Nitrogen monoxide, NO(g), is produced in internal combustion and jet engines.

In an exhaust pipe catalytic converter, NO reacts with carbon monoxide, CO , to form $\mathrm{N}_{2}$ .

State the initial and final oxidation states of nitrogen.

Initial:
Final:

[Maximum number: 2]

Phosphorus is an element that is an essential part of the biological molecules involved in both respiration and photosynthesis.

Explain why the first ionization energy decreases as you descend group 15 from nitrogen to bismuth.

[Maximum number: 2]

Phosphorus is an element that is an essential part of the biological molecules involved in both respiration and photosynthesis.

Explain why the first ionization energy decreases as you descend group 15 from nitrogen to bismuth.

[Maximum number: 1]

What are the oxidation states of the elements in $\mathrm{Na}_{2} \mathrm{CrO}_{4}$ ?

Sodium

Chromium

Oxygen

-1

-2

[Maximum number: 3]

A sample of bromine has the following composition by mass:

\begin{array}{cc} { }^{79} \mathrm{Br}: & 50.75 \% \\ { }^{81} \mathrm{Br}: & 49.25 \% \end{array}

(a)

Deduce the equation, and the colour change observed, for the reaction of dilute bromine water with aqueous iodide solution.

Equation:

Colour change:

[ 2 ]

(b)

Outline why bromine does not react with an aqueous chloride solution.

[ 1 ]

[Maximum number: 4]

A sample of bromine has the following composition by mass:

\begin{array}{cc} { }^{79} \mathrm{Br}: & 50.75 \% \\ { }^{81} \mathrm{Br}: & 49.25 \% \end{array}

(a)

Explain, with reference to electron structure, why the ionic radii of period 4 ions $\mathrm{Ca}^{2+}, \mathrm{Co}^{2+}$ and $\mathrm{Br}^{-}$ are different. Use section 10 of the data booklet.

[ 3 ]

(b)

An iron object is electroplated with cobalt, using an aqueous cobalt(II) bromide electrolyte.

[ 1 ]

(i)

Deduce an equation for the reaction of chlorine gas with aqueous bromide solution.

[ 1 ]

0 selected

Exam points

Question 1

Question 1(a)

Question 1(b)

Question 1(c)

Question 1(c)(i)

Question 1(c)(ii)

Question 1(d)(i)

Question 1(a)(iii)

Question 1(a)(iii)

Question 12

Question 5

Question 5(c)(iv)

Question 5(c)(v)

Question 5

Question 5(c)(iii)

Question 5(e)

Question 5(e)(ii)