Structure and bonding of carbon

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교육자를 위해: Structure and bonding of carbon(Science, Chemistry)을(를) 위한 바로 쓸 수 있는 수업 슬라이드, 복습 노트 — 수업에 사용하거나, 학습자들이 실시간 게임으로 즐기는 인터랙티브 클래스 활동으로 진행하세요.

수업 노트

Diamond: Structure and Bonding

  • Diamond and graphite are allotropes of carbon: both contain only carbon atoms but have different bonding arrangements, making them physically completely different.
  • In diamond, each carbon atom forms four covalent bonds with four other carbon atoms, creating a giant covalent tetrahedral structure.
  • All the covalent bonds in diamond are identical, very strong, and there are no intermolecular forces between separate molecules.
  • All outer shell electrons of each carbon atom are held in the four covalent bonds, so there are no freely moving particles to carry charge.
  • Diamond has a very high melting point because its giant covalent structure has strong covalent bonds that need lots of energy to break.
  • Diamond is extremely hard and dense due to its strong covalent bonds and each carbon atom being bonded to four others.
  • Diamond's hardness makes it useful in cutting tools like drills; it is the hardest naturally occurring mineral but is brittle and can be smashed with a hammer.

Diamond's giant covalent network

Diamond's giant covalent network

Graphite: Structure and Bonding

  • In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings.
  • One electron per carbon atom is delocalised (free to move) and exists between the layers, allowing graphite to conduct electricity.
  • The covalent bonds within the layers are very strong, but the layers are held together by weak intermolecular forces, so they can slide over each other.
  • Graphite is soft and slippery because its layers can slide over each other, making it useful as a lubricant and in pencils.
  • Graphite has a high melting point because it has a giant covalent structure with strong covalent bonds needing lots of energy to break.
  • Graphite can be used to make inert electrodes for electrolysis, important in the extraction of metals such as aluminium.
  • Graphite is similar to metals in that it has delocalised electrons; it does not conduct because of free ions.

Graphite layers and delocalised electrons

Graphite layers and delocalised electrons

Graphene: Structure and Properties

  • Graphene is a single layer of graphite, just one atom thick, consisting of a sheet of carbon atoms covalently bonded in a continuous hexagonal layer.
  • It is essentially a 2D molecule and has very unusual properties that make it useful in composites and electronics.
  • Graphene is extremely strong due to its unbroken pattern and strong covalent bonds between carbon atoms; even stitched patches remain the strongest material.
  • It is also amazingly light, transparent (absorbs 2.3% of visible light), and flexible—it can be twisted, pulled and curved without breaking.
  • Graphene conducts heat and electricity because it has delocalised electrons that can move along its surface; it moves electrons 200 times faster than silicon.
  • Its transparency gives it potential for making computer screens of the future.

Graphene: one carbon layer

Graphene: one carbon layer

Fullerenes: Structure and Uses

  • Fullerenes are carbon allotropes consisting of molecules with hollow tubes or spheres.
  • Their structures are based on interlocking hexagonal rings, but may also contain rings of five or seven carbon atoms.
  • Fullerenes can trap other molecules by forming around them, making them useful for targeted drug delivery systems.
  • They have a huge surface area, useful for trapping catalyst molecules so catalysis can take place.
  • Some fullerenes are excellent lubricants and are used in industrial processes.
  • The first fullerene discovered was Buckminsterfullerene (C60), a hollow sphere of 60 carbon atoms forming 20 hexagons and 12 pentagons, shaped like a football.
  • Buckminsterfullerene was discovered as a component of soot and its discovery won the 1996 Nobel Prize in Chemistry.

Buckminsterfullerene C60

Buckminsterfullerene C60

Carbon Nanotubes

  • Carbon nanotubes are cylindrical fullerenes made by rolling a sheet of graphene into a cylinder.
  • They have very high length to diameter ratios and high tensile strength, resisting breaking or stretching.
  • Like graphene, nanotubes can conduct electricity, making them useful in composites, specialised materials, electronics and nanotechnology.
  • Their properties make them useful for nanotechnology, electronics and materials.

Carbon nanotubes

Carbon nanotubes

Comparing Diamond, Graphite and Graphene

  • Diamond is hard and does not conduct; graphite is soft, slippery and conducts; graphene is a single layer of graphite that is strong, flexible and conducts.
  • Diamond has a giant covalent structure with each carbon bonded to four others; graphite has layers with each carbon bonded to three others.
  • Graphite conducts because of delocalised electrons between layers; diamond does not because all outer electrons are held in covalent bonds.
  • Graphite is soft because its layers slide over each other (weak intermolecular forces); diamond is hard because its rigid covalent network prevents movement.
  • Graphene is similar to graphite in that it is a layer of hexagonal carbon rings, but different because it is only one atom thick.
  • Both diamond and graphite have high melting points due to strong covalent bonds needing lots of energy to break.

Carbon allotropes: diamond and graphite

Carbon allotropes: diamond and graphite

Common Misconceptions to Avoid

  • Graphite does not conduct because of free ions; it conducts because of delocalised electrons.
  • Each carbon atom in graphite forms three bonds, not four.
  • Graphene is a single layer of graphite, not the same as bulk graphite.
  • Diamond does not conduct electricity even though it is a giant structure.
  • The layers in graphite are not held together by covalent bonds; they are held by weak intermolecular forces.

Carbon allotropes: common misconceptions

Carbon allotropes: common misconceptions

슬라이드

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연습 문제

무료 미리 보기 — 63개 중 8개 문제. 가입하면 전부 볼 수 있어요.
  1. 1.Which bonding is found in diamond, graphite and fullerenes?

    Easy
    • AIonic
    • BCovalent
    • CMetallic
    • DCoordinate
  2. 2.Which substance cannot conduct electricity?

    Easy
    • ADiamond
    • BBuckminsterfullerene
    • CGraphite
    • DNanotubes
  3. 3.In graphite, each carbon atom is bonded to how many other carbon atoms?

    Medium
    • ATwo
    • BThree
    • CFour
    • DFive
  4. 4.Why can graphite conduct electricity?

    Medium
    • AGraphite has delocalised electrons
    • BGraphite has layers of atoms that can slide over each other
    • CGraphite has a giant structure
    • DGraphite has strong covalent bonds
  5. 5.Which statement about diamond is correct?

    Medium
    • AIt is a hard substance with a low melting point
    • BEach carbon atom is bonded to three others with strong covalent bonds
    • CIt has a giant structure and conducts electricity
    • DIt has a high melting point with each carbon bonded to four others
  6. 6.Which of the following is not a property of carbon nanotubes?

    Medium
    • AHigh tensile strength
    • BHigh melting point
    • CPoor conductor of electricity
    • DStrong covalent bonds
  7. 7.Which of the following are properties of Buckminsterfullerene? (select all that apply)

    Medium
    • AStrong metallic bonds
    • BA hollow shape
    • CEach carbon is bonded to four other carbon atoms
    • DHigh melting point
    • EStrong covalent bonds
    • FPoor conductor of electricity
  8. 8.Graphite is slippery because it has weak covalent bonds between its layers.

    Easy

    True or false?

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