Chemistry C3 Revision notes

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Chemistry revision notes
Chemistry revision notes
In the 19th century, chemists were finding new elements almost every year
John Dalton from Manchester arranged the elements in order of their mass; he
published a book about this.
In 1863 John Newlands built on Dalton's ideas with his law of octaves. He saw that
the property of every eighth element was similar, he produced a table of his octaves
but was so determined to make it work that he made several vital mistakes: He
assumed that all elements had been found; he filled his octaves regardless of the fact
that some weren't similar and also put some in the same spot. His ideas weren't
One year earlier a French chemis called Alexandre-Emile Beguyer de Chancourtois had
already got a better idea of it, however when his work was published the diagram was
left out which meant the explanation made no sense.
In 1869 Dmitri Mendeleev cracked the problem, at this time 50 elements had been
identified. He placed them in the order of their atomic masses. He arranged them so
that their physical and chemical properties could be seen. He was very smart because
he left gaps for elements which had not yet been discovered but he predicted their
properties from the table. A few years later his theory was proven. He was the father
of the periodic table.
The modern periodic table is ordered by the mass of the atoms and grouped in
groups which behave in a similar way.
We now arrange elements by their atomic number (Proton) this puts them all in the
right place in the periodic table.
Group 1: The reactivity INCREASES going down the group as the atoms get bigger
the single electron in the outer shell energy level is attracted less strongly to the
positive nucleus. This is because it is further away from the nuclease and the inner
shells of the electrons screen it from the positive charge of the nucleus. The outer
electron is easier to lose, so elements lower down the group are MORE Reactive.
Group 7: The reactivity DECREASES going down the group as the atoms get bigger
and electron added to the outer energy is attracted less strongly to the positive
nucleus. This is because it is further away from the nucleus, and the inner shells of
the electrons screen it from the positive charge on the nucleus. An extra electron is
less easily attracted to the outer shell, so elements lower down the group are LESS
Alkali metals tend to lose electrons when they for form chemical bonds.
Reactive metals ­ These metals react vigorously with other elements like oxygen or
chlorine and with water. They are all soft. Some can even be cut with a knife.
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Chemistry revision notes
Transition metals ­ This group contains the elements that most people think of
when the word metal is mentioned. Like iron copper silver and gold. These metals are
not usually very reactive; some like silver and gold are so unreactive that they're
called noble metals.…read more

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Chemistry revision notes
The halogens are a group of poisonous non metals which all have coloured vapours.
The halogens all look different. They all have covalent bonds.
Fluorine is a very reactive poisonous, pale yellow gas
Chlorine is a reactive, poisonous dense green gas which can be identified using damp
litmus paper by its bleaching
Bromine is a dense poisonous dark orange-brown liquid which vaporises easily (More
Iodine is a poisonous dark grey crystalline solid which produces violet coloured
vapour when heated.…read more

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Chemistry revision notes
Brass is a combination of copper and zinc and cupro-nickel is a very hard alloy of
copper and nickel which is used to make the coins for our currency.
Many of the transition metals to form coloured compounds. We use coloured ions
of the transition elements in different ways. Pottery glazes contain transition metal
ions to give bright colours. Copper carbonate is pretty green and generally called
`Verdigris' it is why copper is used for many statues.…read more

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Chemistry revision notes
alkali have reacted completely is called the end point of the reaction. We show this
by using a chemical indicator.
The pH of a solution where it is neither alkali nor acid is 7. If the acid in a titration
reaction reacts completely with a weak alkali then an acid is produced. On the other
hand if an alkali reacts completely with a weak acid then the alkali solution is
produced.…read more

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Chemistry revision notes
This is measured in grams of solute per 100 grams of solver at a particular
temperature. Solubility often increases as temperature increases.
A saturated solution is one in which as much solute possible has been dissolved until
the solution becomes saturated again, as a hot saturated solution cools. Some of
the solute will come out of the solutions. This is called crystallising.
The amount of a substance that will dissolve in a solvent affected by the
temperature of the solvent.…read more

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Chemistry revision notes
Soft water does not contain dissolved substances that produce scum or scale.
Softening hard water is often useful in industry as it can save a lot of money.
A method used to soften water is using washing soda which adds CO32- to produced
CaCO3. This reaction is similar to the production of lime scale however it happens
quickly and it happens where we want it to happen so it can be removed easier.
The second method is called the ion exchange Colum.…read more

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Because energy has to be supplied to break chemical bonds, breaking bonds in an
endothermic reaction and energy is taken from the surroundings
But when new bonds are formed then energy is released, this is exothermic.
Energy level diagrams show us the relative amounts of energy contained in the
reactants and the products formed.…read more

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Chemistry revision notes
Some metal ions form coloured precipitates with Sodium hydroxide
Copper produces blue precipitates
Iron (II) produces dirty green precipitates
Iron (III) produces reddish brown precipitates
Sodium hydroxide has also been known to test for ammonium ions in an unknown
substance because it usually reacts to form ammonia and water.
A substance with ammonia can be heated up to give ammonia off as a gas which can
be detected with red litmus paper.
Testing for negative ions can be done in various ways.…read more

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Chemistry revision notes
Find the empirical formula by finding the ratio.
Instruments are used in various industries to identify, measure and mix different
Analysis is and identification is important for healthcare for example, dialysis
machines can produce high amounts of aluminium which can be very dangerous so
the water must be regularly tested
The development of modern instrumental methods has been aided by the rapid
progress made in technologies such as electronics and computing.…read more


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