Practice Structure 1. Models of the particulate nature of matter with authentic IB Chemistry exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like atomic structure, chemical reactions, and organic chemistry. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
The elements sodium and magnesium are located in Period 3 of the periodic table and show predictable patterns in electron arrangement.
Write the electron configuration of sodium () and magnesium ().
Deduce the number of core and valence electrons in each atom.
State and explain which atom has a higher first ionization energy.
Magnesium can also form a ion. Explain how its electron configuration changes and why this ion is stable.
Aluminium is used in electrical wiring and reflective coatings due to its chemical and physical properties.
State the atomic number of aluminium.
Write the full electron configuration of a neutral aluminium atom.
State the number of valence electrons in an aluminium atom.
Explain why aluminium tends to form a 3+ ion when it reacts.
Sodium vapour lamps are used in street lighting and emit a characteristic yellow light.
State the atomic number of sodium.
Write the full electron configuration of a neutral sodium atom.
Identify the electron that is removed when sodium forms an ion.
The diagram below shows the 4s and 3d orbitals of an atom.
State what the boxes and arrows represent in an orbital box diagram.
State the full electron configuration for a neutral atom that would have exactly five electrons filling these orbitals.
Draw the orbital box diagram for the atom described in part 2.
Explain why the 4s orbital is filled before the 3d orbitals when electrons are added to an atom.
A student collects hydrogen gas produced by the reaction of magnesium with hydrochloric acid. The volume of gas collected is at 298 K and 101 kPa .
Explain why the volume of hydrogen gas collected increases when the temperature rises, assuming pressure remains constant.
Calculate the amount in moles of hydrogen gas collected.
A student investigates the melting behaviour of three substances: X, Y, and Z. The data collected are shown below.
Table 1. Mass of substance and temperature change during heating
| Substance | Mass (g) | Time to melt (s) | Initial temp (°C) | Final temp (°C) | Melting point Observed (°C) |
|---|---|---|---|---|---|
| X | 5.00 | 60 | 22 | 140 | 134 |
| Y | 5.00 | 25 | 21 | 130 | 106–120 |
| Z | 5.00 | 45 | 23 | 135 | 118 |
State one piece of evidence from the data that suggests substance Y is a mixture.
Determine the average rate of temperature increase for substance Z in °C per second.
Using the data, discuss the melting behaviour of substance X and substance Y.
The substances are cooled and observed again. Only substance X reforms a solid with the same sharp melting point on reheating.
Suggest what this indicates about the type of matter in substance X.
Suggest one improvement to this experiment that would help determine whether a substance is pure more accurately.
The diagram below shows a simple apparatus used to investigate the properties of sodium chloride and carbon tetrachloride in both solid and molten states.
State the type of bonding present in sodium chloride and in carbon tetrachloride.
Explain why sodium chloride does not conduct electricity in the solid state but does when molten.
Suggest why carbon tetrachloride does not conduct electricity in any state.
Use the diagram and your knowledge of structure and bonding to deduce which substance(s) contain delocalized ions.
State and explain the difference in melting point between sodium chloride and carbon tetrachloride.
Predict the state of carbon tetrachloride at room temperature. Justify your answer based on its intermolecular forces.
Draw the Lewis (electron dot) structure for the ion and a molecule
The diagram below shows the energy levels of the He+ ion.
State what the energy value of 0 kJ mol-1 represents for the He+ ion.
Calculate the wavelength, in nm, of the photon emitted when an electron falls from to . (Planck’s constant , speed of light )
Determine the first ionization energy of the He+ ion in .
Compare the energy required for the electron transitions from to for the He+ ion and the H atom.
Sketch a diagram showing the emission spectrum for He+ corresponding to transitions ending at (Lyman series), indicating the trend in line spacing.
Discuss why the emission lines converge at high frequencies, and how this convergence relates to ionization.
A student collects a gas sample in a syringe after a reaction between magnesium and hydrochloric acid. The volume of gas collected is at and .
Convert the gas volume to for use in calculations.
Use the ideal gas equation to calculate the amount in moles of gas collected.
Magnesium reacts with excess HCl according to:
Determine the mass of magnesium that would have been used to produce this amount of gas.
State one assumption made when using the ideal gas law in this experiment.
A student is studying two isotopes of chlorine: and .
State the number of protons in both isotopes.
Deduce the number of neutrons in each isotope.
Explain why the chemical properties of these two isotopes are almost identical.