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C4 Chemical Patterns
Elements are arranged in order of proton number (atomic number). This is the
number of positive protons in each atom.
In the Periodic Table each element is placed beneath those with similar properties. It
helps to predict how they will behave in different situations.
A group is a column in the table which contains elements with different properties.
Group 1 contains the elements lithium (Li) to francium (Fr), and Group 7 contains the
elements fluorine (F) to astatine (At).
Because there are patterns in the way the elements are arranged in the Periodic
Table, it can be used to predict their properties.
A period is a row in the periodic table. Across each row, the elements on the left are
metals, while those on the right are nonmetals.
In a row across the table, the elements get less metallic.
Each period starts with a very reactive metal in group 1 and ends with an unreactive
gas in group 8.
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Physical Properties of the Alkali Metals:
Reaction in air Lithium, sodium and potassium are all soft metals. The freshly
cut surface is a shiny, silver colour, but tarnishes quickly to a dull grey as the
metal reacts with oxygen and water in the air.
They are stored in oil to prevent these reactions.
Melting and Boiling Points The alkali metals have low melting and boiling
Density The alkali metals have low densities.…read more
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Lithium Lithium floats when added to water. It fizzes steadily and becomes smaller,
until it eventually disappears.
Sodium When sodium is added to water, the sodium melts to form a ball that
moves around on the surface. It fizzes rapidly, and the hydrogen produced may burn
with an orange flame before the sodium disappears.
Potassium When potassium is added to water, the metal melts and floats. It moves
around very quickly on the surface of the water. The hydrogen ignites instantly.…read more