Edexcel IGCSE Chemistry Covalent Bonding Notes PDF

Edexcel​ ​IGCSE​ ​Chemistry Topic​ ​1:​ ​Principles​ ​of​ ​chemistry Covalent​ ​bonding Notes www.pmt.education 1.44​ ​know​ ​that​ ​a​ ​covalent​ ​bond​ ​is​ ​formed​ ​between​ ​atoms​ ​by​ ​the​ ​sharing​ ​of a​ ​pair​ ​of​ ​electrons...

Edexcel​ ​IGCSE​ ​Chemistry Topic​ ​1:​ ​Principles​ ​of​ ​chemistry Covalent​ ​bonding Notes www.pmt.education 1.44​ ​know​ ​that​ ​a​ ​covalent​ ​bond​ ​is​ ​formed​ ​between​ ​atoms​ ​by​ ​the​ ​sharing​ ​of a​ ​pair​ ​of​ ​electrons Covalent​ ​bonding​ ​occurs​ ​in​ ​most​ ​non-metallic​ ​elements​ ​and​ ​in​ ​compounds​ ​of nonmetals When​ ​atoms​ ​share​ ​pairs​ ​of​ ​electrons,​ ​they​ ​form​ ​covalent​ ​bonds.​ ​These​ ​bonds between​ ​atoms​ ​are​ ​strong. 1.45​ ​understand​ ​covalent​ ​bonds​ ​in​ ​terms​ ​of​ ​electrostatic​ ​attractions Strong​ ​bonds​ ​between​ ​atoms​ ​that​ ​are​ ​covalently​ ​bonded​ ​are​ ​the​ ​result​ ​of electrostatic​ ​attraction​ ​between​ ​the​ ​positive​ ​nuclei​ ​of​ ​the​ ​atoms​ ​and​ ​the​ ​pairs​ ​of negative​ ​electrons​ ​that​ ​are​ ​shared​ ​between​ ​them 1.46​ ​understand​ ​how​ ​to​ ​use​ ​dot-and-cross​ ​diagrams​ ​to​ ​represent​ ​covalent bonds​ ​in:​ ​diatomic​ ​molecules,​ ​including​ ​hydrogen,​ ​oxygen,​ ​nitrogen, halogens​ ​and​ ​hydrogen​ ​halides,​ ​inorganic​ ​molecules​ ​including​ ​water, ammonia​ ​and​ ​carbon​ ​dioxide,​ ​organic​ ​molecules​ ​containing​ ​up​ ​to​ ​two carbon​ ​atoms,​ ​including​ ​methane,​ ​ethane,​ ​ethene​ ​and​ ​those​ ​containing halogen​ ​atoms some​ ​from​ ​the​ ​above​ ​list: hydrogen​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​hydrogen​ ​chloride ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​water​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​methane www.pmt.education ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​oxygen​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​carbon​ ​dioxide 1.47​ ​explain​ ​why​ ​substances​ ​with​ ​a​ ​simple​ ​molecular​ ​structures​ ​are​ ​gases​ ​or liquids,​ ​or​ ​solids​ ​with​ ​low​ ​melting​ ​and​ ​boiling​ ​points;​ ​the​ ​term intermolecular​ ​forces​ ​of​ ​attraction​ ​can​ ​be​ ​used​ ​to​ ​represent​ ​all​ ​forces between​ ​molecules Substances​ ​that​ ​consist​ ​of​ ​small​ ​molecules​ ​are​ ​usually​ ​gases​ ​or​ ​liquids​ ​that​ ​have low​ ​boiling​ ​and​ ​melting​ ​points. Substances​ ​that​ ​consist​ ​of​ ​small​ ​molecules​ ​have​ ​weak​ ​intermolecular​ ​forces between​ ​the​ ​molecules.​ ​These​ ​are​ ​broken​ ​in​ ​boiling​ ​or​ ​melting,​ ​not​ ​the​ ​covalent bonds. Substances​ ​that​ ​consist​ ​of​ ​small​ ​molecules​ ​don’t​ ​conduct​ ​electricity,​ ​because small​ ​molecules​ ​do​ ​not​ ​have​ ​an​ ​overall​ ​electric​ ​charge. 1.48​ ​explain​ ​why​ ​the​ ​melting​ ​and​ ​boiling​ ​points​ ​of​ ​substances​ ​with​ ​simple molecular​ ​structures​ ​increase,​ ​in​ ​general,​ ​with​ ​increasing​ ​relative​ ​molecular mass The​ ​intermolecular​ ​forces​ ​increase​ ​with​ ​the​ ​size​ ​of​ ​the​ ​molecules,​ ​so​ ​larger molecules​ ​(i.e.​ ​molecules​ ​with​ ​greater​ ​relative​ ​molecular​ ​masses)​ ​have​ ​higher melting​ ​and​ ​boiling​ ​points. 1.49​ ​explain​ ​why​ ​substances​ ​with​ ​giant​ ​covalent​ ​structures​ ​are​ ​solids​ ​with high​ ​melting​ ​and​ ​boiling​ ​points Substances​ ​that​ ​consist​ ​of​ ​giant​ ​covalent​ ​structures​ ​are​ ​solids​ ​with​ ​very​ ​high melting​ ​points. All​ ​of​ ​the​ ​atoms​ ​in​ ​these​ ​structures​ ​are​ ​linked​ ​to​ ​other​ ​atoms​ ​by​ ​strong​ ​covalent bonds. These​ ​bonds​ ​must​ ​be​ ​overcome​ ​to​ ​melt​ ​or​ ​boil​ ​these​ ​substances. www.pmt.education 1.50​ ​explain​ ​how​ ​the​ ​structures​ ​of​ ​diamond,​ ​graphite​ ​and​ ​C60​ ​fullerene influence​ ​their​ ​physical​ ​properties,​ ​including​ ​electrical​ ​conductivity​ ​and hardness Diamond In​ ​diamond​ ​(right),​ ​each​ ​carbon​ ​is​ ​joined​ ​to​ ​4​ ​other​ ​carbons covalently. o It’s​ ​very​ ​hard,​ ​has​ ​a​ ​very​ ​high​ ​melting​ ​point​ ​and​ ​does​ ​not conduct​ ​electricity. Graphite In​ ​graphite,​ ​each​ ​carbon​ ​is​ ​covalently​ ​bonded​ ​to​ ​3​ ​other​ ​carbons,​ ​forming​ ​layers of​ ​hexagonal​ ​rings,​ ​which​ ​have​ ​no​ ​covalent​ ​bonds​ ​between​ ​the​ ​layers. o The​ ​layers​ ​can​ ​slide​ ​over​ ​each​ ​other​ ​due​ ​to​ ​no​ ​covalent​ ​bonds​ ​between the​ ​layers,​ ​but​ ​weak​ ​intermolecular​ ​forces.​ ​Meaning​ ​that​ ​graphite​ ​is​ ​soft and​ ​slippery. One​ ​electron​ ​from​ ​each​ ​carbon​ ​atom​ ​is​ ​delocalised. o This​ ​makes​ ​graphite​ ​similar​ ​to​ ​metals,​ ​because​ ​of​ ​its​ ​delocalised electrons. o It​ ​can​ ​conduct​ ​electricity​ ​–​ ​unlike​ ​Diamond. Graphene Single​ ​layer​ ​of​ ​graphite Has​ ​properties​ ​that​ ​make​ ​it​ ​useful​ ​in​ ​electronics​ ​and​ ​composites Carbon​ ​can​ ​also​ ​form​ ​fullerenes​ ​with​ ​different​ ​numbers​ ​of​ ​carbon​ ​atoms​. Molecules​ ​of​ ​carbon​ ​atoms​ ​with​ ​hollow​ ​shapes They​ ​are​ ​based​ ​on​ ​hexagonal​ ​rings​ ​of​ ​carbon​ ​atoms,​ ​but​ ​they​ ​may​ ​also​ ​contain rings​ ​with​ ​five​ ​or​ ​seven​ ​carbon​ ​atoms The​ ​first​ ​fullerene​ ​to​ ​be​ ​discovered​ ​was​ ​Buckminsterfullerene​ ​(C60),​ ​which​ ​has​ ​a spherical​ ​shape Carbon​ ​nanotubes Cylindrical​ ​fullerenes​ ​with​ ​very​ ​high​ ​length​ ​to​ ​diameter​ ​ratios Their​ ​properties​ ​make​ ​them​ ​useful​ ​for​ ​nanotechnology,​ ​electronics​ ​and​ ​materials 1.51​ ​know​ ​that​ ​covalent​ ​compounds​ ​do​ ​not​ ​usually​ ​conduct​ ​electricity exceptions​ ​include:​ ​graphite​ ​and​ ​graphene www.pmt.education