Giant structures and material performance

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Big idea: giant structures and material performance

Key concept: Relationships. The arrangement of atoms and bonds explains material properties. Graphite has mobile electrons and layers; diamond has a rigid three-dimensional covalent network.
Related concepts: Models and evidence. Use a scientific explanation to make predictions, then test it against observations.
Global context: Scientific and technical innovation. Structure-property relationships guide choices for electrodes, cutting tools and electronic materials.

Introduction to Giant Structures

Giant covalent structures contain billions of non-metal atoms joined by strong covalent bonds in a giant lattice.
Diamond and graphite are allotropes of carbon – same element, different bonding arrangements.
Giant structures have very high melting points due to many strong bonds.
Silicon(IV) oxide (SiO₂) is also a giant covalent compound.

Diamond – Structure & Properties

Each carbon atom bonds to four others in a tetrahedral arrangement.
All bonds are identical, very strong covalent bonds; no intermolecular forces.
Does not conduct electricity – all outer electrons are used in bonds.
Extremely hard and dense – used in cutting tools and drills.
Very high melting point – many strong bonds need lots of energy to break.
Hard but brittle (can be smashed with a hammer).

Graphite – Structure & Properties

Each carbon atom bonds to three others, forming layers of hexagons.
One delocalised electron per carbon atom is free to move between layers.
Conducts electricity – delocalised electrons carry charge.
High melting point – strong covalent bonds within layers.
Slippery – layers held by weak intermolecular forces can slide over each other.
Used as a lubricant, in pencils, and as electrodes (unreactive, conducts).

Silicon(IV) Oxide (SiO₂)

Giant covalent structure – each Si bonds to 4 O atoms, each O bonds to 2 Si atoms.
Forms a tetrahedral arrangement similar to diamond.
Very hard, high melting point, insoluble in water, does not conduct electricity.
Occurs naturally as sand and quartz.
Used to make sandpaper and to line furnaces (cheap, heat-resistant).

Metallic Bonding

Metals consist of a giant lattice of positive metal ions surrounded by a ‘sea of delocalised electrons’.
The metallic bond is the electrostatic attraction between positive ions and delocalised electrons.
High melting/boiling points – strong metallic bonds require lots of energy to break.
Good conductors of heat and electricity – delocalised electrons move freely.
Malleable and ductile – layers of ions can slide over each other without breaking bonds.

Metallic bonding

Think like a scientist

Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica.
Comparison: the giant structure being compared. Outcome: hardness and electrical conductivity.
Control: compare samples at the same temperature. Explain why this makes the comparison fairer.
Evidence: Use a consistent method, repeated observations where appropriate and a table with labelled quantities and units. Keep unexpected results and investigate their cause.
Safety: Practical activities need teacher supervision and an appropriate risk assessment. Use the provided data or simulation where the investigation specifies it.
Inquiry task: State a testable question, predict the outcome using the science, then explain how your observations would support or challenge the prediction.

Evaluate the science

Structure-property relationships guide choices for electrodes, cutting tools and electronic materials.
An idealised structure predicts trends, but defects, purity and manufacturing affect real material performance.
Evaluation task: Link your conclusion to evidence, identify a limitation and suggest a specific improvement. Distinguish a measured result from an explanation of its cause.

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1.Which statement about carbon allotropes is correct?
Medium
- ADiamond contains carbon atoms bonded to three other carbon atoms.
- BGraphite is a good conductor of electricity because of the presence of mobile ions.
- CDiamond is used as a lubricant because of the weak intermolecular forces between its layers.
- DGraphite is a good conductor of electricity because it contains delocalised electrons.
2.Which row describes how graphite can be used in electrolysis?
Medium
- ADelocalised electrons – conducts electricity
- BDelocalised electrons – acts as an insulator
- CLow melting point – acts as an insulator
- DLow melting point – conducts electricity
3.Which statement correctly describes the bonding in metals?
Easy
- AA lattice of negative ions in a 'sea of electrons'.
- BA lattice of positive ions in a 'sea of electrons'.
- CA lattice of neutral atoms with delocalised electrons.
- DA lattice of negative ions with delocalised electrons.
4.Which row provides a correct description of the properties of metals?
Easy
- Amelting point high, boiling point low, conducts electricity yes
- Bmelting point low, boiling point high, conducts electricity yes
- Cmelting point low, boiling point low, conducts electricity no
- Dmelting point high, boiling point high, conducts electricity yes
5.What other property does graphite have that makes it useful for electrodes?
Medium
- AGraphite is an unreactive substance and doesn’t react with the electrolyte.
- BGraphite is soft and easy to shape into electrodes.
- CGraphite has a low melting point due to the weak forces in between the layers.
- DGraphite dissolves readily in water.
6.Which of the following statements about graphite and diamond are incorrect? 1 They are allotropes of carbon. 2 They both conduct electricity. 3 They form different numbers of bonds within their structures. 4 They have different uses.
Medium
- A2 and 3
- B2 only
- C1, 3 and 4
- D2 and 4
7.Which statement correctly describes the structure of macromolecules?
Medium
- AGiant molecular crystal which is held together by weak intermolecular forces.
- BGiant molecular crystal which is held together by strong ionic bonds.
- CGiant molecular crystal which is held together by weak metallic bonds.
- DGiant molecular crystal which is held together by strong covalent bonds.
8.Which statement about graphite and diamond is not correct?
Medium
- AGraphite is a good lubricant due to the weak forces in between the layers.
- BDiamond is used as a drill tip because it is an extremely hard substance.
- CGraphite has a low melting point due to the weak forces in between the layers.
- DDiamond is an allotrope of carbon.

Plus de questions

9.The following statements describe the structure and properties of silicon(IV) oxide. 1. Giant covalent structure held together by many strong covalent bonds. 2. It is a very hard substance. Which of the following is correct for statements 1 and 2?
Medium
- AStatement 2 is correct but statement 1 is incorrect.
- BBoth statements are incorrect.
- CBoth are correct and statement 1 explains statement 2.
- DBoth are correct and statement 2 explains statement 1.
10.Statements 1, 2 and 3 are about diamond and graphite. 1. They have atoms that form three equally strong bonds 2. They are both formed from the same element 3. They each conduct electricity Which statement(s) is / are correct?
Medium
- A1 only
- B2 only
- C1 and 3
- D1 and 2
11.Silicon(IV) oxide and phosphorus(V) oxide are oxides of elements in Period 3 of the Periodic Table. Which row describes the correct properties of these two oxides?
Hard
- Anature acidic, type of bonding covalent, melting point of SiO2 high, melting point of P4O10 low
- Bnature acidic, type of bonding covalent, melting point of SiO2 low, melting point of P4O10 low
- Cnature basic, type of bonding ionic, melting point of SiO2 high, melting point of P4O10 low
- Dnature basic, type of bonding ionic, melting point of SiO2 low, melting point of P4O10 low
12.Which statement correctly describes the arrangement of atoms in silicon dioxide?
Medium
- AEach silicon atom is bonded to two oxygen atoms and each oxygen atom is bonded to one silicon atom.
- BEach silicon atom is bonded to four oxygen atoms and each oxygen atom is bonded to two silicon atoms.
- CEach silicon atom is bonded to four oxygen atoms and each oxygen atom is bonded to four silicon atoms.
- DEach silicon atom is bonded to two oxygen atoms and each oxygen atom is bonded to four silicon atoms.
13.Which of the following statements about silicon(IV) dioxide and diamond are correct? 1 Silicon(IV) dioxide forms a giant ionic lattice structure. 2 They are both compounds. 3 They both have very high melting points. 4 There are strong covalent bonds in silicon(IV) dioxide.
Medium
- A1 and 3
- B1 only
- C1, 2 and 4
- D3 and 4
14.Which row correctly describes the use of graphite and silicon(IV) dioxide?
Medium
- Agraphite: electrodes, silicon(IV) dioxide: production of plastics
- Bgraphite: electrolyte, silicon(IV) dioxide: production of glass
- Cgraphite: electrolyte, silicon(IV) dioxide: production of plastics
- Dgraphite: electrodes, silicon(IV) dioxide: production of glass
15.Which row provides a correct description of the structure and properties of silicon(IV) oxide? (✓ = yes, × = no)
Medium
- Aforms an acidic oxide: ✓, has a giant structure: ✓, conducts electricity: ×
- Bforms an acidic oxide: ✓, has a giant structure: ×, conducts electricity: ✓
- Cforms an acidic oxide: ×, has a giant structure: ✓, conducts electricity: ×
- Dforms an acidic oxide: ×, has a giant structure: ×, conducts electricity: ✓
16.Metallic bonds are very strong and give metals their properties. Which of the following definitions is correct for a metallic bond?
Medium
- AA metallic bond is formed by the electrostatic attraction that occurs due to electron transfer between metal atoms.
- BA metallic bond is formed by the electrostatic attraction between the positive ions and the delocalised electrons.
- CA metallic bond is formed by the electrostatic attraction that occurs due to the uneven sharing of electrons between metal atoms.
- DA metallic bond is formed by the intermolecular forces between the positive metal ions and the delocalised electrons.
17.Metals are malleable and ductile and can be hammered and pulled into useful shapes. Which statement correctly explains these properties?
Medium
- ALayers of atoms in the metal lattice are rigid and held strongly together so they cannot move.
- BLayers of atoms in a metal can slide over one another and break the attractive forces that hold them together.
- CLayers of atoms in a metal can slide over one another and new attractive forces are formed between the metal ions and the delocalised electrons.
- DLayers of atoms in a metal cannot slide over one another and the attractive forces between the metal ions and the delocalised electrons are unbreakable.
18.Which of the following is an allotrope of carbon?
Easy
- ASilicon dioxide
- BGraphite
- CSodium chloride
- DCarbon dioxide
19.Why does diamond have a very high melting point?
Easy
- AIt has weak intermolecular forces between layers.
- BIt has strong covalent bonds throughout the structure.
- CIt has delocalised electrons that require much energy to move.
- DIt has ionic bonds between carbon atoms.
20.Which property allows graphite to be used as a lubricant?
Easy
- AIt has delocalised electrons.
- BIt has a high melting point.
- CThe layers can slide over each other due to weak forces between them.
- DIt is hard and dense.
21.In metallic bonding, the delocalised electrons are responsible for which property?
Medium
- AHigh melting point only
- BElectrical conductivity only
- CBoth electrical conductivity and malleability
- DNeither electrical conductivity nor malleability
22.Which statement best explains why silicon(IV) oxide is hard and has a high melting point?
Medium
- AIt has a giant ionic lattice with strong electrostatic forces.
- BIt has a giant covalent structure with many strong covalent bonds.
- CIt has simple molecules held by strong intermolecular forces.
- DIt has a metallic lattice with delocalised electrons.
23.Which of the following substances does NOT conduct electricity in any state?
Medium
- AGraphite (solid)
- BCopper (solid)
- CSilicon(IV) oxide (solid)
- DMolten sodium chloride
24.The structures of two solids X and Y are described below. X has layers of hexagonal rings with weak forces between layers, and Y has a tetrahedral arrangement with each atom bonded to four others. What are the correct uses of these structures?
Medium
- AX: industrial lubricant; Y: glass cutter
- BX: industrial lubricant; Y: industrial lubricant
- CX: glass cutter; Y: industrial lubricant
- DX: glass cutter; Y: glass cutter
25.Silicon(IV) oxide and phosphorus(V) oxide are oxides of elements in Period 3. Which row describes the correct properties of these two oxides?
Medium
- Anature: acidic, bonding: covalent, melting point SiO2: high, melting point P4O10: low
- Bnature: acidic, bonding: covalent, melting point SiO2: low, melting point P4O10: low
- Cnature: basic, bonding: ionic, melting point SiO2: high, melting point P4O10: low
- Dnature: basic, bonding: ionic, melting point SiO2: low, melting point P4O10: low
26.In an experiment, a student tests the electrical conductivity of four solids. Which solid is most likely to conduct electricity as a solid?
Easy
- ADiamond
- BSilicon(IV) oxide
- CGraphite
- DSodium chloride
27.A student is given a sample of a white solid. It is very hard, has a very high melting point, and does not conduct electricity in any state. What is the most likely identity of the solid?
Medium
- AGraphite
- BSilicon(IV) oxide
- CCopper
- DSodium chloride
28.Which property of graphite is correctly explained by its structure?
Medium
- AIt is hard because of strong covalent bonds between layers.
- BIt conducts electricity because of delocalised electrons between layers.
- CIt has a low melting point because of weak covalent bonds within layers.
- DIt is slippery because of strong covalent bonds between layers.
29.Which statement about diamond is correct?
Easy
- ADiamond contains carbon atoms bonded to three other carbon atoms.
- BDiamond is a good conductor of electricity.
- CDiamond is used as a lubricant because of weak forces between layers.
- DDiamond is an allotrope of carbon.
30.Which row correctly describes the structure and bonding in silicon(IV) oxide?
Easy
- AGiant ionic lattice, strong electrostatic forces
- BGiant covalent lattice, strong covalent bonds
- CGiant metallic lattice, delocalised electrons
- DSimple molecular, weak intermolecular forces
31.Complete the sentence: In graphite, each carbon atom is bonded to ___ other carbon atoms.
Easy
In graphite, each carbon atom is bonded to ____ other carbon atoms.
32.Complete the sentence: In metallic bonding, the positively charged metal ions are surrounded by a 'sea of ___'.
Easy
In metallic bonding, the positively charged metal ions are surrounded by a 'sea of ____'.
33.Explain why diamond is extremely hard.
Medium
34.Explain why diamond is very hard and has a high melting point.
Medium
35.A student is asked to design an experiment to compare the hardness of diamond and silicon(IV) oxide. Which method would be most appropriate?
Medium
- AMeasure the electrical conductivity of each substance.
- BTry to scratch each substance with a steel nail.
- CHeat each substance and record the temperature at which it melts.
- DAdd each substance to water and check for solubility.
36.Which statement explains why metals are malleable?
Medium
- AThe layers of atoms can slide over each other because the metallic bonds are weak.
- BThe layers of positive ions can slide over each other and new metallic bonds form.
- CThe atoms are held together by strong covalent bonds that break easily.
- DThe delocalised electrons prevent the layers from moving.
37.Which substance has a giant covalent structure?
Easy
- ASodium chloride
- BGraphite
- CCopper
- DIce
38.A student measures the electrical conductivity of a substance in solid and molten states. The results show it does not conduct when solid but conducts when molten. What type of structure does the substance most likely have?
Medium
- AGiant covalent
- BGiant ionic
- CGiant metallic
- DSimple molecular
39.Which row correctly describes the uses of graphite and silicon(IV) oxide?
Medium
- AGraphite: electrodes; Silicon(IV) oxide: production of glass
- BGraphite: production of glass; Silicon(IV) oxide: electrodes
- CGraphite: lubricant; Silicon(IV) oxide: production of plastics
- DGraphite: cutting tools; Silicon(IV) oxide: lubricant
40.In an experiment to test the hardness of two solids, a student tries to scratch each with a piece of quartz. Solid A is scratched, solid B is not. What can be concluded?
Medium
- ASolid A is harder than quartz.
- BSolid B is harder than quartz.
- CBoth solids are harder than quartz.
- DQuartz is harder than both solids.
41.Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. What is the independent variable?
Easy
- Athe giant structure being compared
- Bhardness and electrical conductivity
- Cthe number of repeated trials
- Dthe scientific explanation written afterwards
42.Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. Which observation or quantity is the dependent variable?
Easy
- Athe giant structure being compared
- Bhardness and electrical conductivity
- Cthe title given to the investigation
- Dthe number of references in the report
43.Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. Which decision best controls another factor in this comparison?
Medium
- Achange every condition for each trial
- Buse a different measurement method for every result
- Ccompare samples at the same temperature
- Drecord only results that agree with the prediction
44.Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. Why should the class repeat measurements or check multiple comparable observations?
Medium
- ATo guarantee that every systematic error disappears
- BTo make an unsupported prediction become correct
- CTo avoid reporting results that disagree with a model
- DTo assess variation and judge how consistent the evidence is
45.A class is evaluating an application of giant structures and material performance. Which statement identifies a relevant limitation?
Hard
- AAn idealised structure predicts trends, but defects, purity and manufacturing affect real material performance.
- BAll scientific models reproduce every feature of the real world
- COne favourable result proves that a technology has no disadvantages
- DA conclusion needs no evidence when a scientific term is used
46.Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. Which conclusion is most justified by a controlled comparison?
Hard
- AA claim that the result must hold in all possible conditions
- BA conclusion restricted to the tested conditions, with uncertainty and limitations stated
- CA claim that alternative explanations never need testing
- DA claim based only on the most convenient observation
47.Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. Select the two practices that strengthen the validity of this comparison.
Medium
- Acompare samples at the same temperature
- Bchange the measurement method whenever a result is unexpected
- Crecord hardness and electrical conductivity using the same agreed procedure
- Dreport only observations that confirm the prediction
48.When evaluating evidence about giant structures and material performance, select the two scientifically defensible statements.
Hard
- AOne result proves the explanation in every situation
- BAn idealised structure predicts trends, but defects, purity and manufacturing affect real material performance.
- CA conclusion should state the conditions and uncertainty of the evidence
- DModels never need revision when new evidence appears
49.Design a fair investigation for this question: Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. Identify what to compare, what to record and one control.
Medium
50.Explain one use of the science in giant structures and material performance and evaluate one limitation of the evidence or application.
Hard
51.Graphite conducts electricity while diamond does not under ordinary conditions. Which structural explanation is consistent?
Hard
- AGraphite contains freely moving carbon ions
- BDiamond has no electrons anywhere in its structure
- CGraphite has mobile delocalised electrons; diamond's bonding electrons are localised
- DGraphite conducts only because its layers are neutral molecules
52.A company compares two nominally identical ceramic samples and finds different strengths. Which follow-up most directly tests a material-model limitation?
Hard
- AAssume the weaker result is impossible and delete it
- BUse the chemical formula alone as a complete strength measurement
- CChange both samples' dimensions without recording them
- DMeasure defects, porosity and purity as well as composition

Notes de révision

## Big idea: giant structures and material performance - **Key concept: Relationships.** The arrangement of atoms and bonds explains material properties. Graphite has mobile electrons and layers; diamond has a rigid three-dimensional covalent network. - **Related concepts: Models and evidence.** Use a scientific explanation to make predictions, then test it against observations. - **Global context: Scientific and technical innovation.** Structure-property relationships guide choices for electrodes, cutting tools and electronic materials. ## Introduction to Giant Structures - **Giant covalent structures** contain billions of non-metal atoms joined by **strong covalent bonds** in a giant lattice. - Diamond and graphite are **allotropes of carbon** – same element, different bonding arrangements. - Giant structures have very high melting points due to many strong bonds. - Silicon(IV) oxide (SiO₂) is also a giant covalent compound. ## Diamond – Structure & Properties - Each carbon atom bonds to **four others** in a **tetrahedral** arrangement. - All bonds are **identical, very strong covalent bonds**; no intermolecular forces. - **Does not conduct electricity** – all outer electrons are used in bonds. - **Extremely hard** and dense – used in cutting tools and drills. - **Very high melting point** – many strong bonds need lots of energy to break. - Hard but **brittle** (can be smashed with a hammer). ## Graphite – Structure & Properties - Each carbon atom bonds to **three others**, forming **layers of hexagons**. - One **delocalised electron** per carbon atom is free to move between layers. - **Conducts electricity** – delocalised electrons carry charge. - **High melting point** – strong covalent bonds within layers. - **Slippery** – layers held by **weak intermolecular forces** can slide over each other. - Used as a **lubricant**, in **pencils**, and as **electrodes** (unreactive, conducts). ## Silicon(IV) Oxide (SiO₂) - **Giant covalent structure** – each Si bonds to **4 O** atoms, each O bonds to **2 Si** atoms. - Forms a **tetrahedral** arrangement similar to diamond. - **Very hard**, **high melting point**, **insoluble in water**, **does not conduct electricity**. - Occurs naturally as **sand** and **quartz**. - Used to make **sandpaper** and to **line furnaces** (cheap, heat-resistant). ## Metallic Bonding - Metals consist of a **giant lattice** of **positive metal ions** surrounded by a **‘sea of delocalised electrons’**. - The **metallic bond** is the electrostatic attraction between positive ions and delocalised electrons. - **High melting/boiling points** – strong metallic bonds require lots of energy to break. - **Good conductors of heat and electricity** – delocalised electrons move freely. - **Malleable** and **ductile** – layers of ions can slide over each other without breaking bonds. ## Think like a scientist - Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. - **Comparison:** the giant structure being compared. **Outcome:** hardness and electrical conductivity. - **Control:** compare samples at the same temperature. Explain why this makes the comparison fairer. - **Evidence:** Use a consistent method, repeated observations where appropriate and a table with labelled quantities and units. Keep unexpected results and investigate their cause. - **Safety:** Practical activities need teacher supervision and an appropriate risk assessment. Use the provided data or simulation where the investigation specifies it. - **Inquiry task:** State a testable question, predict the outcome using the science, then explain how your observations would support or challenge the prediction. ## Evaluate the science - Structure-property relationships guide choices for electrodes, cutting tools and electronic materials. - An idealised structure predicts trends, but defects, purity and manufacturing affect real material performance. - **Evaluation task:** Link your conclusion to evidence, identify a limitation and suggest a specific improvement. Distinguish a measured result from an explanation of its cause.

Structure of Silicon Dioxide: Describe the giant covalent structure of silicon(IV) oxide (SiO2) and compare it to diamond.
Structure of Diamond and Graphite: Describe the giant covalent structures of diamond and graphite, including bonding and arrangement of atoms.
Properties of Diamond and Graphite: Explain the physical properties (hardness, melting point, electrical conductivity, lubricating ability) of diamond and graphite in terms of their structures.
Metallic Bonding and Properties: Describe metallic bonding as the electrostatic attraction between positive metal ions and delocalised electrons, and explain properties of metals (high melting point, conductivity, malleability).
Designing scientific inquiries: Plan a fair comparison: Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica.
Evaluating evidence and impacts: Structure-property relationships guide choices for electrodes, cutting tools and electronic materials. An idealised structure predicts trends, but defects, purity and manufacturing affect real material performance.
Introduction to Giant Structures: **Giant covalent structures** contain billions of non-metal atoms joined by **strong covalent bonds** in a giant lattice.
Diamond – Structure & Properties: Each carbon atom bonds to **four others** in a **tetrahedral** arrangement.
Graphite – Structure & Properties: Each carbon atom bonds to **three others**, forming **layers of hexagons**.
Silicon(IV) Oxide (SiO₂): **Giant covalent structure** – each Si bonds to **4 O** atoms, each O bonds to **2 Si** atoms.
Metallic Bonding: Metals consist of a **giant lattice** of **positive metal ions** surrounded by a **‘sea of delocalised electrons’**.
Giant covalent structures: **Giant covalent structures** contain billions of non-metal atoms joined by **strong covalent bonds** in a giant lattice.
strong covalent bonds: **Giant covalent structures** contain billions of non-metal atoms joined by **strong covalent bonds** in a giant lattice.
allotropes of carbon: Diamond and graphite are **allotropes of carbon** – same element, different bonding arrangements.
four others: Each carbon atom bonds to **four others** in a **tetrahedral** arrangement.
tetrahedral: Forms a **tetrahedral** arrangement similar to diamond.

Cartes mémo

Which statement about carbon allotropes is correct?

Graphite is a good conductor of electricity because it contains delocalised electrons. In graphite, each carbon atom is bonded to three others, leaving one delocalised electron per carbon atom that can move and carry charge, making graphite a good conductor. Diamond bonds to four carbons and does not conduct.

Which row describes how graphite can be used in electrolysis?

Delocalised electrons – conducts electricity Graphite has delocalised electrons that can move and carry charge, allowing it to conduct electricity. It has a high melting point due to strong covalent bonds, not low.

Which statement correctly describes the bonding in metals?

A lattice of positive ions in a 'sea of electrons'. In metallic bonding, metal atoms lose outer electrons to become positive ions, and the delocalised electrons form a 'sea' around them, held by electrostatic attraction.

Which row provides a correct description of the properties of metals?

melting point high, boiling point high, conducts electricity yes Metals generally have high melting and boiling points due to strong metallic bonds, and they conduct electricity because delocalised electrons are free to move.

What other property does graphite have that makes it useful for electrodes?

Graphite is an unreactive substance and doesn’t react with the electrolyte. Graphite is chemically inert (unreactive) towards many electrolytes, making it suitable as an electrode material. It has a high melting point and is insoluble in water.

Which of the following statements about graphite and diamond are incorrect? 1 They are allotropes of carbon. 2 They both conduct electricity. 3 They form different numbers of bonds within their structures. 4 They have different uses.

2 only Statement 2 is incorrect because diamond does not conduct electricity (all electrons are in bonds), while graphite does. Statements 1, 3, and 4 are correct.

Which statement correctly describes the structure of macromolecules?

Giant molecular crystal which is held together by strong covalent bonds. Macromolecules (giant covalent structures) are held together by strong covalent bonds throughout the lattice, not by weak forces or ionic/metallic bonds.

Which statement about graphite and diamond is not correct?

Graphite has a low melting point due to the weak forces in between the layers. Graphite has a high melting point because it has strong covalent bonds within layers; only the layers slide easily due to weak forces, but the overall melting point is high.

The following statements describe the structure and properties of silicon(IV) oxide. 1. Giant covalent structure held together by many strong covalent bonds. 2. It is a very hard substance. Which of the following is correct for statements 1 and 2?

Both are correct and statement 1 explains statement 2. Silicon(IV) oxide has a giant covalent structure with strong covalent bonds, which makes it very hard. So both are correct, with 1 explaining 2.

Statements 1, 2 and 3 are about diamond and graphite. 1. They have atoms that form three equally strong bonds 2. They are both formed from the same element 3. They each conduct electricity Which statement(s) is / are correct?

2 only Both diamond and graphite are allotropes of carbon (same element). In graphite, each carbon forms three bonds; in diamond, each carbon forms four bonds, so statement 1 is false. Only graphite conducts electricity, so statement 3 is false.

Silicon(IV) oxide and phosphorus(V) oxide are oxides of elements in Period 3 of the Periodic Table. Which row describes the correct properties of these two oxides?

nature acidic, type of bonding covalent, melting point of SiO2 high, melting point of P4O10 low Silicon(IV) oxide is acidic, covalent, and has a high melting point (giant covalent). Phosphorus(V) oxide is also acidic and covalent but has a low melting point (simple molecular).

Which statement correctly describes the arrangement of atoms in silicon dioxide?

Each silicon atom is bonded to four oxygen atoms and each oxygen atom is bonded to two silicon atoms. In silicon dioxide (SiO2), each silicon forms four single bonds to oxygen atoms, and each oxygen forms two bonds (one to each of two silicon atoms), creating a giant covalent network.

Which of the following statements about silicon(IV) dioxide and diamond are correct? 1 Silicon(IV) dioxide forms a giant ionic lattice structure. 2 They are both compounds. 3 They both have very high melting points. 4 There are strong covalent bonds in silicon(IV) dioxide.

3 and 4 Silicon(IV) dioxide is a giant covalent structure, not ionic (1 false). Diamond is an element, not a compound (2 false). Both have high melting points (3 true) and strong covalent bonds (4 true).

Which row correctly describes the use of graphite and silicon(IV) dioxide?

graphite: electrodes, silicon(IV) dioxide: production of glass Graphite is used as electrodes (conducts electricity, unreactive). Silicon(IV) dioxide (sand) is used in glass production. It is not an electrolyte or used for plastics.

Which row provides a correct description of the structure and properties of silicon(IV) oxide? (✓ = yes, × = no)

forms an acidic oxide: ✓, has a giant structure: ✓, conducts electricity: × Silicon(IV) oxide is an acidic oxide (reacts with bases), has a giant covalent structure, and does not conduct electricity (no free electrons or ions).

Metallic bonds are very strong and give metals their properties. Which of the following definitions is correct for a metallic bond?

A metallic bond is formed by the electrostatic attraction between the positive ions and the delocalised electrons. Metallic bonding is the electrostatic attraction between positive metal ions and the 'sea' of delocalised electrons. It is not electron transfer (ionic) nor covalent sharing.

How would you design the inquiry for giant structures and material performance?

Compare teacher-provided hardness and conductivity measurements for diamond, graphite and silica. Compare the giant structure being compared; record hardness and electrical conductivity; compare samples at the same temperature.

What limitation matters when applying giant structures and material performance?

An idealised structure predicts trends, but defects, purity and manufacturing affect real material performance.

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