The Periodic Table

The Periodic table is a method of classifying elements.
They are arranged in order of increasing atomic number.
Made up of rows called periods and columns called groups
Metals are to the left and non-metals are to the right.
Elements in the same group have similar properties.
Group number tells us the number of valency electrons and the period number tells us about the number of electron shells

Periodic Trends

Non-metals are on the right side of the periodic table, and metals are on the left.
Down a period of metals they become more reactive
With non-metals, going down a period, the non-metal becomes less reactive

Alkali Metals

Lithium, sodium and potassium

Chemical Properties	Physical Properties
Form ionic compounds	Good conductors of heat and electricity.
React violently with chlorine	Are soft, compared to other metals.
Burst into flames when heated with oxygen: (A red flame for lithium), (A yellow flame for sodium), (A lilac flame for potassium)	They have low densities for metals.
Produce soluble white compounds.	They have low melting and boiling points compared to most metals.
React with cold water.

Patterns

Reactivity, density & softness increases down the group
Melting and boiling points decreases down the group.
Reactivity increases as more electron shells means there is weaker attraction between nucleus & valency electron so is lost more easily.

Halogens

Properties	Patterns
Form colored gases, at RTP: (Fluorine is a yellow gas), (Chlorine is a green gas), (Bromine is a red liquid), (Iodine is a black solid)	Down the group; size, mass and density increase
Are poisonous	Down the group, color darkens
Brittle and crumbly when solid	Reactivity decreases down the group, because it has to gain an electron, so the closer the electron is to the positive nucleus the more easily it will be gained, so atoms with fewer shells will react more easily.
Do not conduct electricity
Form diatomic molecules

Transition Metals

High melting points (except mercury)
Malleable and ductile
Good conductors of heat & electricity (silver is the best)
High density
Have no trend in reactivity
Can be used as catalysts
Form colored compounds
Can form complex ions as they have variable valences

Noble Gases

Properties	Uses
Density increases down the group	Helium- filling balloons and aircrafts because it is lighter than air and will not catch fire.
M.p. and b.p. increases down the group	Argon -- filling (tungsten) light bulbs to stop the filament reacting with oxygen.
Don't conduct electricity	Neon -- is used in advertising signs because it glows red.
Don't take part in chemical reactions