Giant structures
Introduced| English | Meaning |
|---|---|
| crystalline/ˈkrɪstəlaɪn/ | crystalline |
| simple molecular/ˈsɪmpl məˈlekjʊlə/ | Describing a structure of separate molecules held together by intermolecular forces. |
| giant molecular/ˈdʒaɪənt məˈlekjʊlə/ | A covalent network extending through the whole crystal, as in diamond and silicon(IV) oxide. |
| graphite/ˈɡræfaɪt/ | A form of carbon with layers of bonded atoms, used in pencils and able to conduct electricity through delocalised electrons. |
| diamond/ˈdaɪəmənd/ | A form of carbon in which each atom bonds to four others in a three-dimensional giant covalent structure. |
| delocalised/dɪˈlɒkəlaɪzd/ | Describing electrons that are spread over several atoms rather than confined to one bond or atom. |
Networks without end
- How a substance behaves depends on how its particles are joined.
- There are four main structures of a crystalline 晶体 solid.
- Each one is built from a different kind of bonding.
Giant structure lab
Compare giant structures by particles and bonding.
Diamond and graphite are examples of giant ______ structures.
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Networks of covalently bonded atoms.
Ionic and simple molecular 分子晶体
- Giant ionic: a huge lattice of positive and negative ions, held by strong attraction in every direction (e.g. NaCl, MgO).
- Simple molecular: small molecules — strong bonds inside each, but weak forces between them (e.g. iodine $\text{I}_2$, fullerene $\text{C}_{60}$, ice).
The four crystalline structures: giant ionic, simple molecular, giant covalent and giant metallic
A simple molecular solid (like iodine) has:
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Simple molecular substances are small molecules: strong covalent bonds inside, weak intermolecular forces between.
Giant molecular 原子晶体 and giant metallic
- Giant molecular (giant covalent): a network of atoms joined by strong covalent bonds (e.g. silicon(IV) oxide, graphite 石墨, diamond 金刚石).
- diamond is a rigid 3-D network → very hard; graphite has sliding layers and spare delocalised 离域 electrons → it conducts.
- Giant metallic: metal ions in a sea of delocalised electrons (e.g. copper).
Diamond is a rigid 3D covalent network; graphite has sliding layers and conducts
A giant molecular (giant covalent) structure is:
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Diamond, graphite and silicon(IV) oxide are giant covalent networks of atoms.
Graphite conducts electricity but diamond does not, because graphite:
Difficulty 1/5 · 100 coins + a small bonus on first completion today
Graphite has some delocalised electrons that can move; diamond uses all its electrons in fixed bonds.
Match each structure to an example.
Difficulty 2/5 · 140 coins + a small bonus on first completion today
Giant ionic = NaCl; simple molecular = I₂; giant metallic = copper; giant covalent = diamond/graphite.
Giant vs simple
- Giant structures (covalent, ionic, metallic) have very high melting points.
- Simple molecular substances melt easily — only weak intermolecular forces break.
You've got it
- four structures: giant ionic, simple molecular, giant molecular (covalent), giant metallic
- simple molecular = small molecules, weak forces between (I₂, ice)
- giant molecular = covalent network; diamond (hard 3-D) vs graphite (sliding layers, conducts)
- giant metallic = ions in an electron sea