Chemistry A level note full

Chemistry​ ​Summary(Definitions)

Mole​ ​Concept​ ​and​ ​Stoichiometry

1. Isotopes​​ ​are​ ​atoms​ ​of​ ​the​ ​same​ ​element​ ​with​ ​same​ ​number​ ​of​ ​protons​ ​but
different​ ​number​ ​of​ ​neutrons.
2. Ions​​ ​are​ ​particles​ ​that​ ​have​ ​unequal​ ​number​ ​of​ ​protons​ ​and​ ​electrons.
3. A​ ​molecule​​ ​is​ ​a​ ​group​ ​of​ ​atoms​ ​covalently​ ​bonded​ ​together​ ​in​ ​an​ ​element​ ​or
a​ ​compound.
4. Element​​ ​is​ ​the​ ​smallest​ ​particle​ ​of​ ​substance​ ​that​ ​can​ ​exist​ ​alone​ ​under
ordinary​ ​conditions.
5. Relative​ ​molecular/isotopic/atomic/formula​ ​mass​​ ​is​ ​the​ ​average​ ​mass​ ​of
one​ ​molecule/isotope/atom/formula​ ​unit​ ​with​ ​respect​ ​to​ ​1/12​ ​of​ ​the​ ​mass​ ​of​ ​a
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C​ ​atom.
6. A​ ​mole​​ ​is​ ​the​ ​amount​ ​of​ ​substance​ ​that​ ​contains​ ​6.02​ ​x​ ​10​23​​ ​particles.
7. Molar​ ​mass​​ ​of​ ​a​ ​substance​ ​is​ ​the​ ​mass​ ​of​ ​one​ ​mole​ ​of​ ​that​ ​substance.
8. Molecular​ ​formula​​ ​of​ ​a​ ​chemical​ ​compound​ ​shows​ ​the​ ​actual​ ​number​ ​of
atoms​ ​of​ ​the​ ​different​ ​elements​ ​in​ ​one​ ​molecule​ ​of​ ​the​ ​compound.
9. Empirical​ ​formula​​ ​of​ ​a​ ​chemical​ ​compound​ ​shows​ ​the​ ​simplest​ ​whole
number​ ​ratio​ ​for​ ​the​ ​atoms​ ​of​ ​different​ ​elements​ ​present​ ​in​ ​the​ ​compound.
10. Concentration​​ ​is​ ​the​ ​amount​ ​of​ ​solute​ ​per​ ​unit​ ​volume​ ​of​ ​solution.
11. Dilution​​ ​is​ ​the​ ​process​ ​of​ ​adding​ ​solvent​ ​to​ ​a​ ​solution​ ​to​ ​lower​ ​the
concentration.
12. Dilution​ ​factor​​ ​is​ ​a​ ​measure​ ​of​ ​how​ ​much​ ​the​ ​solution​ ​is​ ​diluted.



Redox​ ​reaction

1. Oxidation​​ ​is​ ​a​ ​process​ ​where​ ​a​ ​chemical​ ​species​ ​loses​ ​electrons.
2. Reduction​​ ​is​ ​a​ ​process​ ​where​ ​a​ ​chemical​ ​species​ ​gains​ ​electrons.
3. Redox​ ​reaction​​ ​refers​ ​to​ ​a​ ​reaction​ ​in​ ​which​ ​one​ ​reactant​ ​species​ ​undergo
oxidation​ ​and​ ​another​ ​reactant​ ​species​ ​undergo​ ​reduction​ ​simultaneously.
4. An​ ​oxidising​ ​agent​​ ​is​ ​a​ ​chemical​ ​species​ ​that​ ​cause​ ​the​ ​other​ ​reactant​ ​in​ ​a
redox​ ​reaction​ ​to​ ​be​ ​oxidised​ ​and​ ​itself​ ​reduced.
5. A​ ​reducing​ ​agent​​ ​is​ ​a​ ​chemical​ ​species​ ​that​ ​cause​ ​the​ ​other​ ​reactant​ ​in​ ​a
redox​ ​reaction​ ​to​ ​be​ ​reduced​ ​and​ ​itself​ ​oxidised.
6. Oxidation​ ​state​​ ​is​ ​the​ ​hypothetical​ ​charge​ ​it​ ​would​ ​have​ ​if​ ​the​ ​shared
electrons​ ​in​ ​covalent​ ​bonds​ ​were​ ​assigned​ ​to​ ​the​ ​more​ ​electronegative​ ​atom.
7. A​​ ​disproportionation​ ​reaction​​ ​is​ ​a​ ​redox​ ​reaction​ ​in​ ​which​ ​one​ ​species​ ​is
simultaneously​ ​oxidised​ ​and​ ​reduced.



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, Atomic​ ​structure

1. Orbitals​​ ​is​ ​defined​ ​as​ ​a​ ​region​ ​of​ ​three-dimensional​ ​space​ ​around​ ​the
nucleus,​ ​whereby​ ​there​ ​is​ ​a​ ​95%​ ​chance​ ​of​ ​locating​ ​a​ ​particular​ ​electron.



Chemical​ ​Bonding

1. Metallic​ ​bond​ ​refers​ ​to​ ​the​ ​electrostatic​ ​forces​ ​of​ ​attraction​ ​between​ ​a​ ​lattice
of​ ​positive​ ​ions​ ​and​ ​the​ ​‘sea’​ ​of​ ​delocalised​ ​electrons.
2. Ionic​ ​bond​​ ​is​ ​the​ ​electrostatic​ ​attraction​ ​between​ ​oppositely​ ​charged​ ​ions​ ​in
an​ ​ionic​ ​compound.
3. Covalent​ ​bond​​ ​is​ ​the​ ​electrostatic​ ​attraction​ ​between​ ​shared​ ​pair​ ​of​ ​electrons
and​ ​the​ ​positively​ ​charged​ ​nuclei.
4. Bond​ ​length​​ ​is​ ​the​ ​distance​ ​between​ ​the​ ​nuclei​ ​of​ ​the​ ​two​ ​atoms.
5. A​ ​σ​ ​bond​​ ​is​ ​the​ ​single​ ​region​ ​of​ ​overlap​ ​that​ ​is​ ​formed​ ​by​ ​the​ ​head-on​ ​overlap
of​ ​orbitals.
6. A​ ​𝜋​ ​bond​​ ​is​ ​two​ ​separate​ ​region​ ​overlap​ ​that​ ​is​ ​formed​ ​by​ ​the​ ​sideway
overlap​ ​of​ ​two​ ​orbitals.
7. Electronegativity​​ ​is​ ​the​ ​ability​ ​of​ ​an​ ​atom​ ​in​ ​a​ ​covalent​ ​bond​ ​to​ ​attract
electrons​ ​to​ ​it.
8. VSEPR​ ​postulates:
● Electron​ ​pairs​ ​in​ ​the​ ​valence​ ​shell​ ​around​ ​a​ ​central​ ​atom​ ​repel​ ​each​ ​other​ ​and
orientate​ ​themselves​ ​in​ ​space​ ​as​ ​far​ ​as​ ​possible​ ​to​ ​minimise​ ​repulsion
between​ ​them.
● Repulsion​ ​between​ ​lone​ ​pair-lone​ ​pair​ ​of​ ​electrons​ ​is​ ​greater​ ​than​ ​lone
pair-bond​ ​pair​ ​of​ ​electrons​ ​is​ ​greater​ ​than​ ​lone​ ​pair-bond​ ​pair​ ​of​ ​electrons,
which​ ​is​ ​in​ ​turn​ ​greater​ ​than​ ​bond​ ​pair-bond​ ​pair​ ​of​ ​electrons.
● Repulsion​ ​between​ ​bond​ ​pair​ ​of​ ​electrons​ ​increase​ ​in​ ​the​ ​electronegativity​ ​of
the​ ​central​ ​atom.




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