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Work of Hamza (Mathemagician) Unit 1.1




Unit 1.2: Formulae, equations and moles

Learning bit:

Avogadros constant is the number of carbon atoms in exactly 12g of the carbon12
isotope. It is equal to 6.02x 10^23 mol^1.

One mole of a substance is the amount of that substance that contains 6.02x…

Page 2

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Work of Hamza (Mathemagician) Unit 1.1




Moles

There are 3 ways of calculating the amount of substance (in moles):

1. For pure substance (X)
Amount of X (in moles) = mass of X (in grams)/its molar mass

2. For solutions:
The amount of solute = concentration (in mol dm^3) x…

Page 3

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Work of Hamza (Mathemagician) Unit 1.1




Learny bits:

1. Chemical bonds:
1. Ionic ­ between separate ions
2. Covalent: divided into 2 types
o polar covalent where the bonding pair of electrons is nearer to one atom
o Pure covalent where the bonding pair of electrons is shared equally
o…

Page 4

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Work of Hamza (Mathemagician) Unit 1.1




= (Pi) p bond.










o A dative covalent bond is a covalent bond formed when one of the
overlapping orbitals contained 2 electrons, and the other none.
o A metallic bond results from the delocalisation of the outer electrons
amongst all the atoms. It…

Page 5

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Work of Hamza (Mathemagician) Unit 1.1




o Covalent bonding

These are either:
Giant atomic, such as diamond, graphite and quartz
Simple molecular, such as iodine and many organic molecules
Hydrogenbonded molecular, such as ice and ethanol
Noncrystalline such as polymers

o Effect of heat (melting)

**** It is quite possible…

Page 6

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Work of Hamza (Mathemagician) Unit 1.1










If the number of electrons in 2 different substances is about equal and neither
has hydrogen bonds, then dipole/dipole forces cause a difference in boiling
temperature. This is the case between butane (34 electrons, nonpolar, boiling
temp = 0.5 deg Celsius) and propanone (32…

Page 7

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Work of Hamza (Mathemagician) Unit 1.1





Melting and boiling temps. Of the period 3 elements (Na to Ar)

The melting temperature depends upon the strength of the forces between
particles that separate during melting (or boiling).
These particles may be:
Metal ions in a sea of electrons in metals
Covalently…

Page 8

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Work of Hamza (Mathemagician) Unit 1.1




A reducing agent is a substance that reduces another substance and so is itself
oxidised. The half equation involving a reducing agent has electrons on the
righthand side, i.e it gives electrons to the substance being reduced.
*** remember OIL RIG (Oxidation Is Loss,…

Page 9

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Work of Hamza (Mathemagician) Unit 1.1




e.g. For the overall equation for oxidation of Fe2+ ions by MnO4 ions:

add MnO4 + 8H+ + 5e Mn2+ + 4H2O
to 5 x Fe2+ Fe3+ + e

MnO4 + 8H+ + 5Fe2+ Mn2+ + 4H2O + 5Fe3+



Mathemagician
Topic 1.6: Group 1…

Page 10

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Work of Hamza (Mathemagician) Unit 1.1




Ionisation energies
The value of the 1st ionisation energy for Group 1 and of the 1st and 2nd
ionisation energies for Group 2 decreases down the group. This is
because as the atoms gets larger, the outer electrons are further from
the nucleus and…

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