Chemistry - Periodic Table

Properties of the table

• group = down

• period = across

Across a Period

• no. of electron shells = period number

• metals on the left, non-metal on the right

Down a Group

• elements in the same group = same no. of valence electrons

• grp 1 and 2 have the same no. of electrons as grp number

Group 1 - alkali metals

• alkali metals

• soft, easily cut

• low m.p/b.p

• low densities

• very reactive, stored in water

• alkali metal + water → soluble base (alkali)

grp 1 metal + h2o → grp 1 hydroxide + h2

→ strong alkali, pH 13-14, purple

Group 1 Trends

going down

• m.p/b.p decreases

• density increases

• reactivity increases

Group 17 - halogens

• non-metals

• diatomic

• low m.p/b.p

• coloured

Group 17 Trends

going down

• m.p/b.p increases

• colour intensity increases

• reactivity decreases

Colours and state of grp 17 element

fluorine = pale yellow (gas)

chlorine = greenish yellow (gas)

bromine = reddish brown (liquid)

iodine = purplish black (solid)

Answer format for displacement reactions

• element X is more reactive than Y. Hence it displaces Y ions from Y compound to form X compound and element Y.

• X is less reactive than Y. Hence it is unable to displace Y ions from Y compound and no displacement occurs.

Group 18 - noble gases/insert gases

• monatomic non-metals

• colourless gases

• low m.p/b.p

• insoluble in water

• unreactive

• fully filled valence electron shell