Practice Paper 1 (Cambridge International AS Chemistry)

Which statement about the trend in atomic radius across Period 3 is not correct?

Which statement about the isotope ⁶⁰Co is not correct?

Which row gives the correct order of increasing radius (smallest to largest)?

Which statement does not explain the increase in first ionisation energy across a period?

Table 4.1 below shows the atomic radii for the elements of Period 2, Li to F.

Table 4.1

i) State and explain the trend in atomic radius across Period 2.

ii) Suggest why the atomic radius of neon cannot be determined in the same way as the other Period 2 elements.

Complete Fig. 4.1 to show the full electronic configuration of a boron atom in the ground state.

Fig. 4.1

Explain why the first ionisation energy of boron is lower than the first ionisation energy of beryllium.

The successive ionisation energies for another element, J, are shown in Table 4.2.

Table 4.2

Deduce the formula of the compound formed when element J reacts with chlorine.

Iron and cobalt are adjacent elements in the Periodic Table. Iron has three main naturally occurring isotopes, cobalt has one.

Define the term isotope.

Isotopes of polonium, proton number 84, are produced by the radioactive decay of several elements including thorium, proton number 90. The isotope ²¹³Po is produced from the thorium isotope ²³²Th.

Complete Table 1.1 to show the number of protons, neutrons and electrons in the two isotopes.

Table 1.1

Extract:

Isotopes are atoms of the same element that have:

• The same proton number / atomic number / number of protons
• A different mass number / nucleon number / number of neutrons

Polonium has twenty-five different isotopes.

Explain why the isotopes of polonium exhibit the same chemical properties but their boiling points differ slightly.

i) State the full electronic configuration of a rubidium ion, Rb⁺.

ii) Compare the ionic radius of a rubidium ion to the atomic radius of a krypton atom. Explain your answer.

The third shell consists of the 3s, 3p and 3d sub-shells.

i) State the total number of orbitals present in the third shell.

ii) List the 3d, 4s and 4p sub-shells in order of increasing energy.

Rubidium forms an ionic compound with selenium, Rb₂Se.

Complete Fig. 3.1 to show the electronic configuration of the valence electrons in a selenium atom.

Fig. 3.1

Ionisation energies provide evidence for the electronic structure of atoms.

i) Define the term first ionisation energy.

ii) Construct an equation to represent the second ionisation energy of magnesium. Include state symbols.

iii) Explain the trend in first ionisation energies across Period 3 (sodium to argon). Refer to nuclear charge and shielding in your answer.

Silicon(IV) oxide, SiO₂, and phosphorus(III) chloride, PCl₃, have different structures and physical properties.

i) Describe the structure and bonding of silicon(IV) oxide.

ii) Predict the shape and bond angle of a molecule of phosphorus(III) chloride.

iii) Explain the difference in melting points between silicon(IV) oxide and phosphorus(III) chloride in terms of their structure and bonding.

Ammonia, NH₃, reacts with hydrogen chloride gas to form ammonium chloride, NH₄Cl.

NH₃ + HCl → NH₄Cl

Complete the dot-and-cross diagram to show the bonding in the ammonium ion, NH₄⁺. Show outer electrons only.

Iron has many different naturally occurring isotopes.

What is the relative atomic mass of iron?

When heated, calcium nitrate, Ca(NO₃)₂, will decompose to a white solid and a mixture of gases. One of the gases released is an oxide of nitrogen,Y.

8.2 g of anhydrous calcium nitrate is heated until no further reaction takes place.

What is the mass of Y produced?

A compound has the following composition by mass: H, 5.00%; N, 35.00%; O, 60.00%.

What is the identity of the compound?

The eggshell of a chicken egg makes up 5% of the total egg mass.

The average egg has a mass of 50 g.

Assume that chicken eggshell is pure calcium carbonate.

What is the number of eggshells needed to neutralise 50 cm³ of 2.0 mol dm^-3 ethanoic acid?

Table 3.1 shows the number of protons, neutrons and electrons of some isotopes and ions of copper.

Table 3.1

i) Complete Table 3.1.

ii) State the full electronic configuration of the Cu⁺ ion.

⁶³Cu has a relative isotopic mass of 62.9296 and ⁶⁵Cu has a relative isotopic mass of 64.9278. The relative atomic mass of copper is 63.546.

Calculate the percentage abundance of each isotope of copper. Show your working.

Express your answer to an appropriate number of significant figures.

Explain why isotopes of copper have the same chemical properties but different densities.

Copper(II) chloride reacts with sodium phosphate to form two salts only.

Write a balanced equation for this reaction.

5.0 g of an unknown Group 2 nitrate was decomposed to produce 0.0843 mol of gas.

2X(NO₃)₂ (s) → 2XO (s) + 4NO₂ (g) + O₂ (g)

i) Calculate the amount, in mol, of the unknown Group 2 nitrate.

ii) Calculate the number of ions in 0.03372 mol of the unknown Group 2 nitrate.

Extract:

5.0 g of an unknown Group 2 nitrate was decomposed to produce 0.0843 mol of gas.

2X(NO3)2 (s) → 2XO (s) + 4NO2 (g) + O2 (g)

i) Calculate the amount, in mol, of the unknown Group 2 nitrate.

moles of X(NO3)2 = 0.03372 mol

Identify the unknown element X.

Extract:

2X(NO3)2 (s) → 2XO (s) + 4NO2 (g) + O2 (g)

X = magnesium / Mg

Using your answer to part (b), calculate the mass, in grams, of the metal oxide produced in the complete decomposition of 0.03372 mol of X(NO₃)₂.

Give your answer to 3 significant figures.

Extract:

5.0 g of an unknown Group 2 nitrate was decomposed to produce 0.0843 mol of gas.

2X(NO3)2 (s) → 2XO (s) + 4NO2 (g) + O2 (g)

X = magnesium / Mg

State whether strontium nitrate would need to be heated more or less strongly than X(NO₃)₂ to decompose. Explain your answer.