The periodic table

1. Periodic trends The Periodic Table is an arrangement of the elements in an order of increasing proton

number Elements in the same period have the same number of electron shells

o The period number shows the number of electron shellso As we move left to right, there is a decrease in metallic properties

Elements in the same group have the same number of valence electronso The group number shows the number of electronso The elements have similar chemical properties due to the same valence

electronso As we go down a group,

Proton number increases Atoms get bigger The elements have more metallic properties, as it is easier to lose

electrons The group number of an element shows the number of valence electrons it has.

Group number 1 2 3 4 5 6 7 0Ionic charge +1 +2 +3 tend to from covalent

compounds-2 -1 Do not from

compounds

2. Group properties Alkali metals

o They are Group 1 metals.o They are soft, have low melting and boiling points and low densitieso As we go down the group, the melting and boiling point decreases, while density

generally increases, and reactivity increases o They are very reactive, due to the ease of losing one valence electron to attain

noble gas configuration. They are powerful reducing agents

o They can react with cold water, giving a metal hydroxide and hydrogen Intensity of the reaction increases as we use more reactive metals Sodium gives a yellow flame, potassium, a lilac flame

Halogenso They are Group 7 metals, being non-metals and existing as diatomic moleculeso They have low melting and boiling points, and are colouredo As we go down the group, melting and boiling points increase, the colour of

halogens becomes darker, and reactivity decreases

Nickolas Teo

o They are very reactive, due to the ease of gaining one electron to achieve noble gas configuration.

They are powerful oxidising agentso The more reactive halogens can displace less reactive halogens from their halide

solutions Noble gases

o They are Group 0o They are monatomic elements, colourless, are insoluble in water, are unreactive

and have low melting and boiling points that increases down the groupo Their valence shell is full, giving them stability, thus they do not lose, gain or

share electrons, causing them to be unreactive. They can provide an inert atmosphere (Argon and neon in light bulbs)

Nickolas Teo