periodic table

period number

number of shells

group number

The number of electrons in the outer shell

How did Mendeleev organise his periodic table?

-in order of increasing atomic mass. but not strict

-left gaps for undiscovered elements

-gaps later filled in once discovered

-isotopes proved he was correct for not ordering only on mass but considering physical properties

metals

-form positive ions

-bottom and left of table

non-metals

-form negative ions or react by sharing electrons

-right and top of table

properties of metals

Hard but malleable

High melting and boiling points.

Good conductors of heat and electricity.

properties of non metals

Not malleable or ductile

not shiny

poor conductors of heat and electricity, brittle

Bonding in ionic compounds

- strong electrostatic forces of attracted between +ve and -ve ions

-lattice shape

Group 1: Alkali Metals

1 valence electron, very reactive

As you go down group 1

reactivity increases

Softness increases

density increases

melting point decreases

react group 1 with water

the more vigorous reaction (i.e more bubbles) means more reactive

metal + water

metal hydroxide + hydrogen gas

metal+chlorine

Metal chloride

metal+oxygen

metal oxide

Group 7: Halogens

Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At)

as you go down Group 7

Reactivity decreases

density increases

boiling point increases

atomic mass increases

Fluorine

Pale yellow gas

Chlorine

Pale green gas

Bromine

Organgey -brown liquid

Iodine

Grey solid or purple vapour

what happens when halogens react with metals?

-They form ionic compounds

-halides(F-,Cl-,Br-,I-)

Displacement of halogens

A more reactive halogen can displace a less reactive halogen from an aqueous solution of its salt

test for chlorine, bromine iodine ions

-add dilute nitric acid and silver nitrate solution

test for chlorine ion

forms white precipitate forms.

test for bromine ion

forms cream precipitate

test for iodine ion

forms a yellow precipitate