GCSE AQA Chemistry: C3: Periodic Table/Group 1/Group 7/Transition Metals

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Preview of GCSE AQA Chemistry: C3: Periodic Table/Group 1/Group 7/Transition Metals

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C3 (1): Development Of The Periodic Table
The Early Periodic Table
During the 19th century scientists tried to find ways to classify
elements based on their properties and atomic weight.
In 1863 Newlands (some guy that I don't know the first name of)
came up with the law of octaves (similar properties were repeated
after each eighth element). He put the known elements into groups
depending on their atomic weight, but the group properties didn't
match with his law so no one really paid much attention to him.
In 1869 Mendeleev (another guy without a first name...) made a
better table because he left gaps for all of the undiscovered
elements. Which was really very clever.
When they found some more elements they had the properties
that Mendeleev had predicted and he fitted into his table, so
people began to believe him. The modern periodic table is based
upon Mendeleev's.
The Modern Periodic Table
When scientists discovered protons and electrons they rearranged
the periodic table from atomic weight to atomic number.
The groups have similar properties because their atoms have the
same number of electrons in their outer shell.
Within a group, the reactivity of an element depends on the total
number of electrons. As you go down a group there are more shells
surrounding the atom and the atoms get larger, because the outer
shell is then further away from the atom the forces of attraction
are weaker which makes the element less reactive.
When metals they react they lose electrons. So the reactivity of
metals in a group increases as you go down.
When non-metals react they gain electrons. So the reactivity of
non-metals in a group decreases as you go down.

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Group 1: The Alkali Metals
Some basic stuff about alkali metals:
They are very reactive metals
More reactive as you go down the group
Soft solids at room temperature
Low melting / boiling temperature (this decreases as you go down
the group)
Low density, some float on water (lithium, sodium, potassium)
They react readily with air and water.
Alkali metal + water metal hydroxide + hydrogen
All have one electron in their outer shell.…read more

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All have seven electrons in their outer shell.
They form ionic compounds with metals in which their ions have a
-1 charge.
They bond covalently with non-metals to form molecules.
Reactivity decreases as you go down the group
A more reactive halogen can displace a less reactive halogen from
its compounds in solution (i.e. chlorine + potassium bromide
potassium chloride + bromine)
The Transition Elements
Found in between groups 2 and 3.
They are all metals.…read more

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Many transition elements (and compounds containing transition
elements) are used as catalysts.…read more


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