period 3 - inorganic chemistry

sodium and cold water

2Na(s) +2H2O(l) = 2NaOH(Aq) + H2(g)

• fizzing

• pH: 12-14

magnesium and cold water

Mg(s) + 2H2O(l) = Mg(OH)2(Aq) + H2(g)

• pH: 9-10, weakly alkaline because Mg(OH)2 is not very soluble in water

magnesium and steam

Mg(s) + H2O(g) = MgO(s) + H2(g)

why is sodium more reactive than magnesium?

sodium - Na+

Magnesium - Mg2+

Takes more energy to lose 2 electrons.

sodium + oxygen

2Na(s) + 1/2O2(g) = Na2O(s)

• sodium oxide

aluminium + oxygen

2Al(s) + 1.5 O2(g) = Al2O3(s)

• aluminium oxide

phosphorus and oxygen

P4(s) + 5O2(g) = P4O10(s)

• phosphorus (V) oxide

magnesium and oxygen

Mg(s) + 1/2O2(g) = MgO(s)

• magnesium oxide

silicion and oxygen

Si(s) + O2(g) = SiO2(s)

• silicon dioxide

sulfur + oxygen

S(g) + O2(g) =. SO2(g)

• sulfur dioxide

The trend in the melting point of the highest oxides of the elements Na–S

Na2O, MgO, Al2O3 - GIANT IONIC LATTICE

• MgO highest melting point - greater than Na2O bc it forms 2+ ions so bonds more strongly than 1+ ion from Na2O.

• Al2O3 is lower bc electronegativity between Al and O is weaker than Mg and O. Don’t attract electrons in metal-oxygen bond as strongly as in MgO, makes bonds in Al2O3 partially covalent.

P4O10 and SO2

low melting point, simple molecular structures

Held by weak intermolecular forces, takes minimal energy to break.

SiO2

Giant macromolecular structure ( giant ionic lattice).

In order to break strong covalent bonds need to be broken, requires a lot of energy.

Al2O3 - notes

insoluble in water

But react to with acids and bases to form salts - so acts as an acid and base… called AMPHOTERIC

Phosphorus oxide and water

P4O10(s) + 6H2O(l) = 4H3PO4(Aq)

Sulfur dioxide and water

SO2(g) + H2O(l) = H2SO3(Aq)

sulfur trioxide and water

SO3(l) + H2O(l) = H2SO4(Aq)

sodium and water

Na + H2O = 2NaOH

magensium and cold water

Mg(s) + 2H2O(l) = Mg(OH)2(Aq) + H2(g)

anion formed when phosphorus acid reacts with water

H3PO4(Aq) - 3H+(Aq) + PO3-4(Aq)

anion formed when sulfurous acid/sulfuric(IV) acid reacts with water

H2SO3(Aq) - 2H+(Aq) + SO2-3(Aq) + SO2-3(Aq)

anion formed when sulfuric acid reacts with water

H2SO4(Aq) - 2H+(Aq) + SO2-4(Aq)

acid + base equals…

salt + water

basic oxides…

neutralise acids

Na2O(s) + 2HCl(Aq) = 2NaCl(Aq) + H2O(l)

MgO(s) + H2SO4(Aq) = MgSO4(Aq) + H2O(l)

Acidic oxides…

neutralise bases

Si, P4O10, SO2, SO3

example:

P4O10(s) + 12NaOH(Aq) = 4Na3PO4(Aq) + 6H2O(l)

Amphoteric oxides…

neutralise acids and bases

example:

Al2O3 + 3H2OSO4 = Al(SO4)3(Aq) + 3H2O(l)

Al2O3 + 2NaOH + 3H2O = 2NaAl(OH)4

transition metal

metal that can form one or more stable ions with a partially filled d-subshell.

elements in d-block that aren’t transition metals

Sc forms one ion, (Sc3+) which has an empty d-subshell

Sc3+ -(Ar)

Zn forms one ion, (Zn2+) which has a full d-subshell

(Zn2+) - (Ar)3d104s2

physical properties of transition metals

• high density

• high melting point & boiling point

• more or less same ionic radii

chemical properties of transition metals

• form complex ions

• form coloured ions

• good catalysts

• variable oxidation states

MnO4(-)

purple

Cr2O7(2-)

orange

VO2(+)

yellow

VO(2+)

blue

V(3+)

green

Cr(3+)

violet/green

Fe(3+)

purple/yellow

V(2+)

violet

Mn(2+)

pale pink

Fe(2+)

pale green

CO(2+)

pink

Ni(2+)

green

Cu(2+)

blue

ligand

molecule or ion that donates a pair of electrons to central transition metal ion to form a covalent bond.

co-ordination n.o

n.o of co-ordinate bonds that are formed with a central metal atom or ion

complex ion

a central metal atom or ion surrounded by ligands.

why do tranisiton metals from complex ions

partially filled d subshell can accept lone pairs of electrons from ligands

monodentate

ligand that donates a one pair of electrons -forms one co-ordination bonds.

bidentate

ligand that donates two pairs of electrons - forms two co-ordination bonds.

stereoisomerism

compounds have same structural formula but different arrangement in space.