Structure 3 · Classification of MatterStructure 3 · 物质分类
Classification of Matter物质分类
IB-Style Practice Questions: Structure 3.1 to 3.2IB 风格练习题：覆盖 Structure 3.1 至 3.2
MEDIUMHARDPaper 1Paper 2Paper 3 HLHL
Topics Structure 3.1 to 3.2考点 Structure 3.1 至 3.2HL
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PART I · PAPER 1第一部分 · 第一卷No calculator · multiple choice · 10 marks不可使用计算器 · 选择题 · 10 分
Multiple Choice选择题
Each item carries 1 mark. No calculator or data booklet required unless numerical data are given directly in the question. Items tagged HL test content beyond the standard-level syllabus (variable oxidation states, complex-ion colour, catalysis, magnetism of the transition elements; E/Z isomerism and chirality in organic chemistry).每题 1 分。除非题目中直接给出数值数据，否则不需要计算器或数据手册（data booklet）。标记 HL 的题目考查超出标准级别（SL）大纲的内容：过渡元素的可变氧化态、配合物颜色、催化作用、磁性；有机化学中的 E/Z 异构与手性。
Q1MEDIUMPaper 13.1 Atomic Radius[1]
Which lists Na, Mg, Al, and Si in order of decreasing atomic radius?下列哪一项按原子半径由大到小正确排列了 Na、Mg、Al 和 Si？
The first ionization energy of oxygen ($1314~\mathrm{kJ\,mol^{-1}}$) is lower than that of nitrogen ($1402~\mathrm{kJ\,mol^{-1}}$), even though O lies to the right of N in period 2. What best explains this anomaly?氧的第一电离能（$1314~\mathrm{kJ\,mol^{-1}}$）低于氮（$1402~\mathrm{kJ\,mol^{-1}}$），尽管 O 在第二周期中位于 N 右侧。最佳解释是？
(A)Oxygen has a larger atomic radius than nitrogen.氧的原子半径比氮大。
(B)Nitrogen's half-filled $2p^3$ subshell has extra stability, raising its ionization energy above the general trend; removing an electron from oxygen's $2p^4$ configuration involves repulsion between the two paired electrons in one $2p$ orbital, making removal easier despite O's higher nuclear charge.氮半充满的 $2p^3$ 亚层具有额外稳定性，使其电离能高于一般趋势；而从氧的 $2p^4$ 组态中移走电子涉及同一 $2p$ 轨道中两个成对电子之间的排斥，尽管 O 的核电荷更高，电子仍更容易被移走。
(C)Oxygen has a lower nuclear charge than nitrogen.氧的核电荷比氮低。
(D)Nitrogen's electron configuration is completely full, while oxygen's is not.氮的电子组态是完全充满的，而氧的不是。
Which correctly describes the acid-base character of the solutions formed when $\mathrm{Na_2O}$ and $\mathrm{P_4O_{10}}$ are separately dissolved in water?当 $\mathrm{Na_2O}$ 与 $\mathrm{P_4O_{10}}$ 分别溶于水时，下列哪一项正确描述了所得溶液的酸碱性质？
(A)$\mathrm{Na_2O}$ forms an acidic solution; $\mathrm{P_4O_{10}}$ forms a basic solution.$\mathrm{Na_2O}$ 生成酸性溶液；$\mathrm{P_4O_{10}}$ 生成碱性溶液。
(B)$\mathrm{Na_2O}$ forms a basic solution (NaOH); $\mathrm{P_4O_{10}}$ forms an acidic solution ($\mathrm{H_3PO_4}$).$\mathrm{Na_2O}$ 生成碱性溶液（NaOH）；$\mathrm{P_4O_{10}}$ 生成酸性溶液（$\mathrm{H_3PO_4}$）。
(C)Both form neutral solutions.两者都生成中性溶液。
(D)Both form acidic solutions, since both are oxides of period 3 elements.两者都生成酸性溶液，因为两者都是第三周期元素的氧化物。
Q5HARDPaper 1HL3.1 Transition Metal Oxidation States[1]
Manganese forms compounds such as MnO, $\mathrm{MnO_2}$, and $\mathrm{KMnO_4}$. Which statement correctly explains the range of oxidation states shown by manganese?锰能形成 MnO、$\mathrm{MnO_2}$ 和 $\mathrm{KMnO_4}$ 等化合物。下列哪一项正确解释了锰所呈现的氧化态范围？
(A)Manganese always shows an oxidation state of $+2$ only.锰只呈现 $+2$ 氧化态。
(B)Manganese can show $+2$ (MnO), $+4$ ($\mathrm{MnO_2}$), and $+7$ ($\mathrm{KMnO_4}$), among other states, because the close energies of the $4s$ and $3d$ subshells allow variable numbers of electrons to be lost.锰可呈现 $+2$（MnO）、$+4$（$\mathrm{MnO_2}$）与 $+7$（$\mathrm{KMnO_4}$）等多种氧化态，因为 $4s$ 与 $3d$ 亚层能量相近，使锰可以失去数目可变的电子。
(C)Manganese can only show oxidation states of $+2$ and $+3$.锰只能呈现 $+2$ 和 $+3$ 氧化态。
(D)Manganese's oxidation state is fixed by its group number, so it only ever shows $+7$.锰的氧化态由其所在族数固定，因此它只呈现 $+7$。
Aqueous $[\mathrm{Cu(H_2O)_6}]^{2+}$ is pale blue. What causes this colour?水合铜离子 $[\mathrm{Cu(H_2O)_6}]^{2+}$ 呈淡蓝色。造成这一颜色的原因是？
(A)$\mathrm{Cu^{2+}}$ ions absorb all wavelengths of visible light equally.$\mathrm{Cu^{2+}}$ 离子对所有波长的可见光吸收程度相同。
(B)The ligands split the $d$ orbitals of $\mathrm{Cu^{2+}}$ into two energy levels; an electron absorbs a photon of visible light to be promoted between these split $d$ orbitals, and the complementary colour of the absorbed light is observed.配体使 $\mathrm{Cu^{2+}}$ 的 $d$ 轨道分裂为两个能级；电子吸收一个可见光光子后在分裂的 $d$ 轨道间跃迁，观察到的是被吸收光的互补色。
(C)The blue colour comes from light emitted as electrons fall between main energy levels, the same process responsible for atomic line spectra.蓝色来自电子在主能级之间跃迁时发出的光，这与原子线状光谱的成因相同。
(D)Copper metal is intrinsically blue, and the colour is unrelated to the ligands.铜金属本身就是蓝色的，该颜色与配体无关。
$\mathrm{CH_3CH_2COOH}$ and $\mathrm{CH_3CH_2CHO}$ belong to which two homologous series, respectively?$\mathrm{CH_3CH_2COOH}$ 与 $\mathrm{CH_3CH_2CHO}$ 分别属于哪两个同系列？
How many structural (constitutional) isomers of molecular formula $\mathrm{C_4H_8}$ are non-cyclic alkenes (i.e. contain exactly one C=C double bond)?分子式为 $\mathrm{C_4H_8}$、含且仅含一个 C=C 双键的非环状烯烃，共有多少种结构（构造）异构体？
PART II · PAPER 2第二部分 · 第二卷Calculator + data booklet · structured response · 52 marks可使用计算器与数据手册 · 结构化解答题 · 52 分
Structured Response结构化解答题
Show all working and reasoning in the space provided. Marks for correct method are awarded even if a final statement is incomplete. State units where relevant. Data-booklet values for electronegativity and ionization energy may be quoted directly from memory or from values supplied in the question.在指定区域写出全部推理过程。即便最终表述不完整，方法正确仍可得分。在相关处注明单位。电负性与电离能的数据手册数值可凭记忆引用，或直接使用题目中给出的数值。
SR 1MEDIUMPaper 23.1 Periodic Trends[18]
This question concerns periodic trends across period 3 of the periodic table.本题考查元素周期表第三周期的周期性趋势。
(a)Explain the trend in atomic radius across period 3, from Na to Ar.解释第三周期从 Na 到 Ar 原子半径的变化趋势。[3]
(b)Explain the trend in first ionization energy down group 1, from Li to Cs.解释第 1 族从 Li 到 Cs 第一电离能的变化趋势。[3]
(c)The first ionization energies of magnesium and aluminium are $738~\mathrm{kJ\,mol^{-1}}$ and $578~\mathrm{kJ\,mol^{-1}}$ respectively, even though Al has a greater nuclear charge than Mg. Explain this anomaly in terms of electron configuration.镁与铝的第一电离能分别为 $738~\mathrm{kJ\,mol^{-1}}$ 和 $578~\mathrm{kJ\,mol^{-1}}$，尽管 Al 的核电荷数比 Mg 大。请从电子组态的角度解释这一反常现象。[3]
(d)$\mathrm{Mg^{2+}}$ and $\mathrm{Al^{3+}}$ are isoelectronic (both have the electron configuration of neon). Predict, with a reason, which of the two ions has the larger ionic radius.$\mathrm{Mg^{2+}}$ 与 $\mathrm{Al^{3+}}$ 互为等电子体（两者电子组态均与氖相同）。预测这两种离子中哪一种的离子半径更大，并说明理由。[2]
(e)Explain the trend in electronegativity across period 3, from Na to Cl.解释第三周期从 Na 到 Cl 电负性的变化趋势。[3]
(f)Classify $\mathrm{Na_2O}$, $\mathrm{Al_2O_3}$, and $\mathrm{SO_3}$ as basic, amphoteric, or acidic oxides, and write an equation showing the behaviour of one of them with water.将 $\mathrm{Na_2O}$、$\mathrm{Al_2O_3}$ 和 $\mathrm{SO_3}$ 分类为碱性、两性或酸性氧化物，并写出其中一种与水反应的方程式。[4]
This question concerns HL properties of the first-row transition (d-block) elements.本题考查第一行过渡（d 区）元素的 HL 性质。
(a)Write the full electron configuration of an Fe atom and of an $\mathrm{Fe^{3+}}$ ion, and explain, in terms of subshell energies, why transition metals show variable oxidation states.写出 Fe 原子及 $\mathrm{Fe^{3+}}$ 离子的完整电子组态，并从亚层能量的角度解释为何过渡金属能呈现可变氧化态。[4]
(b)Explain, using the idea of $d$-orbital splitting, why transition metal complexes such as $[\mathrm{Cu(NH_3)_4(H_2O)_2}]^{2+}$ are coloured, while $\mathrm{Sc^{3+}}$ compounds (in which $\mathrm{Sc^{3+}}$ has a $3d^0$ configuration) are colourless.用 $d$ 轨道分裂的概念解释：为何 $[\mathrm{Cu(NH_3)_4(H_2O)_2}]^{2+}$ 等过渡金属配合物是有色的，而 $\mathrm{Sc^{3+}}$（其组态为 $3d^0$）的化合物却是无色的。[4]
(c)Explain how a transition metal, or one of its compounds, can act as a catalyst, referring to variable oxidation states and/or surface adsorption.解释过渡金属或其化合物如何起催化作用，需涉及可变氧化态和/或表面吸附。[3]
(d)Explain, in terms of electron configuration, why compounds of $\mathrm{Fe^{3+}}$ are paramagnetic while compounds of $\mathrm{Zn^{2+}}$ are diamagnetic.从电子组态角度解释：为何 $\mathrm{Fe^{3+}}$ 的化合物具有顺磁性，而 $\mathrm{Zn^{2+}}$ 的化合物是逆磁性的。[3]
(e)Explain the origin of an atomic line emission spectrum in terms of electron transitions between quantized energy levels, and explain how the convergence of spectral lines at high frequency can be used to determine an element's first ionization energy.从电子在量子化能级间跃迁的角度解释原子线状发射光谱的成因，并说明谱线在高频处的收敛如何用来确定元素的第一电离能。[4]
SR 3MEDIUMPaper 2HL3.2 Functional Groups & Isomerism[16]
This question concerns functional-group identification, isomer counting, and stereoisomerism in organic chemistry.本题考查有机化学中的官能团识别、异构体计数与立体异构。
(a)Ethyl 3-hydroxybutanoate has structure $\mathrm{CH_3CH(OH)CH_2COOCH_2CH_3}$. Identify the two functional groups present.3-羟基丁酸乙酯的结构为 $\mathrm{CH_3CH(OH)CH_2COOCH_2CH_3}$。指出其中存在的两种官能团。[2]
(b)State the general formula of the homologous series of alcohols.写出醇同系列的通式。[2]
(c)Molecular formula $\mathrm{C_5H_{12}}$ has three structural isomers. Name all three.分子式 $\mathrm{C_5H_{12}}$ 共有三种结构异构体。写出这三种异构体的名称。[3]
(d)Calculate the degree of unsaturation of a compound with molecular formula $\mathrm{C_8H_8O}$, and suggest a structure consistent with this value.计算分子式为 $\mathrm{C_8H_8O}$ 的化合物的不饱和度，并给出一个与该数值相符的结构。[3]
(e)But-2-ene exists as cis and trans isomers. Explain why this stereoisomerism arises, and state which isomer has the higher boiling point, giving a reason.丁-2-烯存在顺式与反式异构体。解释这种立体异构产生的原因，并指出哪一种异构体沸点更高，并说明理由。[3]
(f)Determine whether 3-chloropentane, $\mathrm{CH_3CH_2CHClCH_2CH_3}$, possesses a chiral centre. Justify your answer by identifying the four groups attached to C3.判断 3-氯戊烷 $\mathrm{CH_3CH_2CHClCH_2CH_3}$ 是否含有手性中心。请列出 C3 上所连接的四个基团，并据此说明理由。[3]
PART III · PAPER 3 HL第三部分 · 第三卷 HLCalculator + data booklet · data-based · 18 marks可使用计算器与数据手册 · 数据题 · 18 分
Data-Based Question (HL)数据题（HL）
This question tests period 3 ionization-energy anomalies and transition-metal complex colour from Structure 3.1, using ionization-energy and colour data. Higher-level students should attempt all parts.本题考查 Structure 3.1 中第三周期电离能反常与过渡金属配合物颜色的相关内容，需用到电离能与颜色数据。HL 学生应作答全部小题。
Table 1 gives the first ionization energy of each period 3 element.表 1 给出第三周期各元素的第一电离能。
Na
Mg
Al
Si
P
S
Cl
Ar
496
738
577
786
1012
1000
1251
1521
(All values in $\mathrm{kJ\,mol^{-1}}$.)（单位均为 $\mathrm{kJ\,mol^{-1}}$。）
Table 2 gives the electron configuration and observed colour of four aqueous first-row transition-metal ions, together with the colour of visible light each absorbs (from the complementary-colour relationship).表 2 给出四种第一行过渡金属水合离子的电子组态与观察到的颜色，以及各自吸收的可见光颜色（依据互补色关系得出）。
Ion离子
$[\mathrm{Sc(H_2O)_6}]^{3+}$
$[\mathrm{Cu(H_2O)_6}]^{2+}$
$[\mathrm{Ni(H_2O)_6}]^{2+}$
$[\mathrm{Co(H_2O)_6}]^{2+}$
$d$ electron count电子数
$3d^0$
$3d^9$
$3d^8$
$3d^7$
Observed colour观察颜色
colourless无色
pale blue淡蓝色
green绿色
pink粉红色
Colour absorbed吸收颜色
none无
orange橙色
red红色
green绿色
(a)Using Table 1, identify the two pairs of neighbouring elements across period 3 where the first ionization energy decreases despite an increase in nuclear charge.利用表 1，找出第三周期中两对相邻元素：尽管核电荷增大，第一电离能却下降。[3]
(b)Explain, in terms of electron configuration and subshell energy, the decrease you identified from Mg to Al.从电子组态与亚层能量的角度，解释你在 Mg 到 Al 之间找到的电离能下降现象。[3]
(c)Explain, in terms of electron configuration, the decrease you identified from P to S.从电子组态的角度，解释你在 P 到 S 之间找到的电离能下降现象。[3]
(d)Using Table 2, explain why $[\mathrm{Sc(H_2O)_6}]^{3+}$ is colourless while the other three complex ions are coloured.利用表 2，解释为何 $[\mathrm{Sc(H_2O)_6}]^{3+}$ 是无色的，而另外三种配离子都是有色的。[4]
(e)Using Table 2 and the complementary-colour relationship, explain why $[\mathrm{Cu(H_2O)_6}]^{2+}$ appears blue while $[\mathrm{Ni(H_2O)_6}]^{2+}$ appears green, and explain in general terms why complex ions of different metals (or the same metal with different ligands) can absorb different colours of visible light.利用表 2 与互补色关系，解释为何 $[\mathrm{Cu(H_2O)_6}]^{2+}$ 呈蓝色而 $[\mathrm{Ni(H_2O)_6}]^{2+}$ 呈绿色，并从一般原理上解释为何不同金属的配离子（或同一金属搭配不同配体）会吸收不同颜色的可见光。[5]