Species such as NH4+, CO32- and PO43- are examples of molecular ions.

1. (a)Ionic and covalent bonds both involve an electrostatic attraction between different species. Identify the species that are electrostatically attracted to one another in: • an ionic bond • a covalent bond.[2]
2. (b)Complete Table 1.1 to show the total numbers of protons and electrons in the molecular ions NH4+, CO32- and PO43-. [Table 1.1][3]
3. (c)(i)NH4+ is a Brønsted-Lowry acid. Define Brønsted-Lowry acid.[1]
4. (c)(ii)When NH4+(aq) is heated with NaOH(aq), a pungent gas is produced. Write an ionic equation for this reaction.[1]
5. (c)(iii)The nitrogen atom in NH₄⁺ is sp³ hybridised. sp³ orbitals form from the mixing of one 2s and three 2p orbitals. Sketch the shapes of a 2s and a 2p, orbital on the axes in Fig. 1.1.[2]
6. (d)(i)There are many naturally occurring hydrated compounds that contain the anion PO43-. Name the anion PO43-.[1]
7. (d)(ii)Struvite is a soft hydrated mineral with Mᵣ = 245.3. The anhydrous form of the mineral has the formula NH4MgPO4. Calculate the number of molecules of water of crystallisation in struvite. Give your answer to the nearest integer. Show your working.[2]
8. (e)(i)OH-(aq) reacts with 2-bromo-2-methylpropane in an SN1 reaction. The molecular ion (CH3)3C+ forms as the intermediate in this reaction. Draw the mechanism for the SN1 reaction of OH- with 2-bromo-2-methylpropane. Include charges, dipoles, lone pairs of electrons and curly arrows as appropriate. Draw the structures of the organic reactant and organic product. [Figure with H3C-C(CH3)-CH3 structure][3]
9. (e)(ii)2-bromo-2-methylpropane is a tertiary bromoalkane. Define tertiary bromoalkane.[1]
10. (e)(iii)Organic compound M forms when 2-bromo-2-methylpropane is heated with ethanolic OH-. Draw the structure of M.[1]

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