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CHEMISTRY UNIT 2 NOTES




Chemistry

Element: A substance made up of one type of atom
Compound: Tow or more different elements chemically bonded together
Mixture: A substance that has two or more different elements which are mixed together
NOT chemically bonded

IONIC BONDING

Ionic Bonding ­ gaining or losing electrons…

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CHEMISTRY UNIT 2 NOTES




Covalent Bonding ­ sharing electrons (between non-metals)
Electrons are shared in a covalent bond
Compounds produced by covalent bonding form molecules
Molecules are individual particles
Group 7 in the Periodic table (Halogens) are diatomic and come in PAIRS as such as
Hydrogen - H, but Hydrogen…

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CHEMISTRY UNIT 2 NOTES




DIAMOND

Diamond is a rare form of carbon ­ each carbon atom is covalently bonded to four other
carbon atoms
This pattern arrangement is repeated millions of times so is a giant lattice
Very hard ­ the hardest substance on earth
Needs a lot of energy…

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CHEMISTRY UNIT 2 NOTES




Metals form giant structures most have high boiling and melting points, are hard and
strong
In a metal the atoms are held together by strong bonds in a regular structure
In a metal there are free electrons from the outer shells of the metal atoms which…

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CHEMISTRY UNIT 2 NOTES




THERMOSETTING POLYMERS

Once moulded, do not soften when heated ­ cannot be reshaped
Polymer chains ­ cross-linkedcannot slide past each other easily
Not broken by heat
Decomposes & chars when heated too far
Cannot be recycled
Much more rigid structure ­ chains are fixed in place…

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CHEMISTRY UNIT 2 NOTES




Elements are made up of one type of atom
Isotopes = Atoms of the same element having the same amount of protons but have
different numbers of neutrons
Isotopes =
o Atoms of the same element
o Different mass no.
o Different neutron no.
The physical…

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CHEMISTRY UNIT 2 NOTES




(16×2)
= 64 ×100 = 50% of oxygen

EMPIRICAL FORMULA OF A COMPOUND

The Empirical formula gives the simplest ratio of elements present in a substance
This is steps in how to calculate it
o Step 1: Find the masses/percentage of the elements
o Step 2:…

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CHEMISTRY UNIT 2 NOTES




4Al + 3O2 2Al2O3

CALCULATING THE MASS OF A PRODUCT

When calculating it only calculate the part of the question it wants you to
First calculate the R.F.M of the parts that it wants you to calculate

E.G. What mass of calcium oxide is produced when…

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CHEMISTRY UNIT 2 NOTES




GC-MS are instrumental methods
Instrumental methods ­ fast, accurate & sensitive (helps detect very small amounts of a
substance)
GC-MS ­ separating a mixture of compounds
Two phases = mobile phase & stationary phase
Mobile phase = Carrier gas carries sample through the column ­ different…

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CHEMISTRY UNIT 2 NOTES




OR




At the start 100% reactant, 0% product
At the end 0% reactant, 100% product
The amount of reactant may be less because some could be lost through a gas




From the x axis draw up o hit the line and go across to get your…

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