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CHEMISTRY…read more

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The early periodic table:
· John Dalton arranged the elements in order of mass, in 1808 he published a table of elements
in his book.
· In 1863 john Newlands build on Dalton's ideas with his law of octaves, he produced the table of
his octaves, but was determined to make it work and made some vital mistakes as he assumed
that all the elements had been found so scientist ridiculed his idea.
· In 1868 the Russian scientist Dmitri Mendeleev cracked the problem, at this time 50 elements
had been found, he placed then in a table by their atomic masses.
· He left gaps in the table for other elements when they were found.
The modern periodic table:
· The group that an element is in is determined by its atomic number.
· The number of electrons in the highest energy level of an atom determines its chemical
· We can explain rends in reactivity as we down a group in terms of the number of energy levels
in the atom.…read more

Slide 3

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Properties of the alkali metals:
· They are all very reactive, they have to be stored in oil to stop them reacting with
oxygen in the air
· Their reactivity increases as you go down the group. They also boil and melt at
relatively low temperatures and as you go down the group the temperatures et
lower and lower.
· the alkali metals have one electron on their outer layers, this gives them similar
· They react with non-metals, losing their single electron and forming a metal
carrying a 1+ charge. They're always an ionic compound.
Reaction with water:
· When adding lithium, sodium or potassium to water the metal moves around on
top and fizzes, the fizzing happens because of the reaction with the water an forms
a hydrogen gas.
· Potassium reacts with water so vigorously that the hydrogen gas produced catches
fire and burns with a lilac flame.
· The reaction between an alkali metal and water also produces a metal hydroxide,
they are soluble in water, producing a colourless solution with a high pH (alkaline
Sodium + water -> sodium hydroxide + hydrogen
Other reactions:
· They also react vigorously with other non-metal such as chlorine and produce
metal chlorides which are white solids and dissolve in water to make a colourless
solution. The reaction gets more and more vigorous as you go down the group,
because the 1+ charge gets easier to lose.…read more

Slide 4

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Properties of the halogens:
· They have very low melting points and boiling points.
· They're poor conductors of heat and electricity.
· Halogens all look different:
· At room temperature Fluorine is a very reactive, poisonous, pale yellow gas.
· Chlorine is a very reactive poisonous, dense green gas.
· Bromine is dense, poisonous dark orange-brown liquid, which vaporises easily and is
· Iodine is a poisonous dark grey crystalline solid which produces a violet vapour when
· Halogens as elements all exist as pairs of atoms joined together by covalent bonds.
Reactions of the halogens:
· They have the highest energy level containing seven electrons, and need just one more to
make them stable.
· They take part in both ionic and covalent bonding, which explains why they are less
reactive as the go down the group because the outer electron is further away and more
shielded from the nucleus.
· Halogens react with metals and gain a single electron forming a 1- charge e.g. Cl-, Br-, I-
· In these reaction ionic salts which we call metal halides are formed e.g. Sodium chloride
and magnesium iodide.
· When halogens are reacted with non-metals, both sets of atoms share electrons to gain a
stable electronic structure, so they are covalent bonds, e.g. Hydrogen chloride.
Displacement reactions between halogens:
· More reactive halogens replace less reactive ones…read more

Slide 5

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Physical properties:
· Many of the transition metals have similar properties, but they also are different
from other elements in the periodic table, they have a typical metallic structure.
· The metal's atoms exist in a giant structure held together by metallic bonds, and
outer electrons of each atom can freely within the metal.
· They are good conductors of electricity and heat because of the delocalised
electrons, as they carry the electrical heat or current, they are hard, tough and
strong but can be bent by a hammer.
Chemical properties:
· Transition elements are much less reactive than the metals in group 1 as they don't
as easily with oxygen or water as the alkali metals, they corrode very slowly, this
means they are good as structural materials.
· They're particularly useful when mixed and made into ALLOYS, iron mixed with
carbon in steels is a well known one of these.
Transition metal compounds:
· Many form coloured compounds, the colours which are produced by the transition
elements are important in the world around us.…read more

Slide 6

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· A proton that is produced as we dissolve an acid in water becomes
surrounded by water molecule which keep it in solution and is the
· Acids in aqueous solutions produce H+ ions and alkalis in aqueous solution
produce H- ions.
Strong and weak acids:
· Strong and weak acids and alkalis are decided by the extent they ionise in
· A strong base is 100% ionised in water
· You can tell if an acid is strong or weak by the pH scale and also by
observing the rate of reaction when adding a reactive metal acid.
1 2 3 4 5 6 7 8 9 10 11 12 13 14…read more

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