period 3 Flashcards
type of structure Na Mg Al
giant lattice
type of structure Si
macromolecular
type of structure P4 S8 Cl2
simple covalent molecules
type of structure Ar
mono atomic
type of bonding Na Mg Al
metallic
type of bonding Si P4 S8 Cl2
covalent
type of forces Na Mg Al
metallic bonds- attraction between positively charged metal ions and delocalised electrons in a lattice
type of forces Si
covalent- shared pair of electrons
type of forces P4 S8 Cl2
VDWs- temporary induced intermolecular forces
type of forces Ar
VDWs
bp and mp Na Mg Al Si
increasingly high
bp and mp P4 S8 Cl2 Ar
low- weak forces
trend across period in atomic radius
decreases
why does atomic radius decrease across period
- more protons
- electrons added to same shell so shielding is same
- attraction between nucleus and outer electrons increases
trend cross period first IE
increases
why does first IE increase across period
- -more protons
- electrons added to same shell so shielding is same
- attraction between nucleus and outer electrons increases
trend in electronegativity across period
increases
observations of sodium with water
fizzes and floats on surface
Na dissolves
sodium and water equation
Na+H2O > NaOH + 1/2H2
observations of magnesium with cold water
- v slow reaction
- occasional bubble
equation magnesium and cold water
Mg + H2O> Mg(OH)2 + H2
observation magnesium with steam
- white flame
- white solid
equation magnesium with steam
Mg + H2O > MgO + H2
why is aluminium unreactive with water
-resistant to further oxidation because of Al2O3 coating
do silicon, phosphorus and sulphur react with water
no
observations chlorine and water
(with universal indicator paper)
red then bleaches white
equation chlorine and water
Cl2 + H2O >< HClO + HCl
what is the reaction of water and chlorine an example of
disproportionation- chlorine simultaneously oxidised and reduced
does argon react with water
no
what do the period 3 elements react with oxygen to form
they react exothermically to form oxides, with the exception of chlorine and argon
observation sodium and oxygen
- orange/yellow flame
- white solid
equation sodium and oxygen
4Na + O2 > 2Na2O
observation magnesium and oxygen
- white flame
- white solid
equation magnesium and oxygen
Mg + 1/2O2 > MgO
observation aluminium and oxygen
- unreactive due to Al2O3 coating
- fine powder- white sparkles/white solid
equation aluminium and oxygen
4Al + 3O2 > 2Al2O3
what kind of compounds are the metal oxides
basic
observations silicon with oxygen
v slow
equation silicon with oxygen
Si+ O2 > SiO2
observations phosphorus and oxygen
white flames and fumes
equation phosphorus and oxygen
4P + 5O2 > P4O10
observations sulphur and oxygen
blue flame
choking gas
equation sulphur and oxygen
S + O2 > SO2
what kind of compounds are non metal oxides
acidic compounds
what can sulphur (IV) oxide (SO2) react with oxygen to form
sulphur (VI) oxide (SO3)
sulphur 4 oxide and oxygen
SO2 + 1/2O2> SO3
contact process
SO3 + H2O > H2SO4
why do NA20, MGO AND AL203 have high melting points
ionic- strong electrostatic attractions between oppositely charged ions require a lot of energy to break
why does SiO2 have a higher melting point than P4O10
SiO2 macromolecular and P4O10 is simple molecular
strong covalent bonds in SiO2 require more energy to break than weak VDW forces between P4O10 molecules
why does P4O10 have a higher melting point that SO3
- P4O10 larger molecules-more electrons than SO3
- p4o10 stronger VDW forces between molecules- more energy to break
in general, what do metal oxides from period 3 elements react with water to form
solutions containing hydroxide ions
sodium oxide and water equation
Na2O + H2O > 2NaOH
pH of resulting solution Na2O and H2O
Na2O is soluble and resulting solution has pH 11-14
magnesium oxide and water equation
MgO + H2O > Mg(OH)2
pH of resulting solution MgO and H2O
sparingly soluble- pH 8-10
is Al2O3 soluble in water
no- pH remains 7
what do non metal oxides of period 3 elements react with water to form
solutions containing H+ ions
SiO2 and water solubility?
insoluble- sand
P4O10 and water equation
P4O10 + 6H2O > 4H3PO4
pH of resulting solution P4O10 and WATER
1-2- STRONG ACID
SO2 and water equation
SO2 + H2O > H2SO3
pH of resulting solution SO2 and water
2-4- weak acid
equation SO3 and water
SO3 + H2O > H2SO4
pH of resulting solution SO3
0-2
examples of ionic oxides
Na2O and MgO
what do ionic oxides react with acids to form and why
salt and water
they are basic
equation sodium oxide and sulphuric acid
Na2O + H2SO4 > Na2SO4 + H2O
equation magnesium oxide and hydrochloric acid
MgO + 2HCl > MgCl2 + H2O
examples of covalent oxides
SiO2, P4O10, SO2, SO3
what do covalent oxides react with aqueous alkali to form and why
salt and water- theyre acidic
equation silicon oxide and sodium hydroxide
SiO2 + NaOH > Na2SiO3 + H2O
equation phosphorus (v) oxide and sodium hydroxide
P2O5 + 6NaOH > 2Na3PO4 + 3H2O
equation sulphur (IV) oxide and sodium hydroxide
SO2 + NaOH > Na2SO3 + H2O
equation sulphur (VI) oxide and sodium hydroxide
SO3 + NaOH > Na2SO4 + H2O
why does aluminium react with both acids and bases
its amphoteric
equation aluminium oxide and hydrochloric acid
Al2O3 + 6HCl > 2AlCl3 + 3H2O
equation aluminium oxide and nitric acid
Al2O3 + 6HNO3 > 2Al(NO3)3 + 3H2O
equation aluminium oxide and sodium hydroxide
Al2O3 + 2NaOH + 3H2O > 2NaAl(OH)4
what do aluminium salts form when dissolved in water
acidic solutions
why do aluminium salts form acidic solutions when dissolved in water
the ionic lattice breaks down and the Al3+ ions become surrounded by water forming a hexaaqua ion
hexaagua ion
[Al(H2O)6]3+
how many water molecules is the Al3+ ion surrounded by
6
how is each water molecule bonded to the aluminium ion
coordinate bond
what does the charge on the Al3+ ion cause the electron density in the water molecule to do
move closer to the metal ion- water molecule polarised
what does the Al3+ ion have enough polarising power to do
weaken the OH bonds in water- one of bonds breaks and a proton donated
equation for hexaagua ion losing proton
[Al(H2O)6]3+ > [Al(H2O)5(OH)]2+ + H+
what does adding a base to an aqueous solution of the hexaaqua aluminium ion produce
an insoluble precipitate of aluminium hydroxide
equation for hexaaqua ion and hydroxide ion
[Al(H2O6)]3+ + OH- > [Al(H2O)5(OH)]2+ + H2O
what happens to the equilibrium if you add more OH- ions to the hexaaqua aluminium ion
shifts to RHS to oppose change and reduce OH concentration and a new equilibrium is set up
what new equilibrium is set up when more OH- ions are added to alumium hexaaqua ions
[Al(H2O)5(OH)]2+ + OH- <> [Al(H2O4)(OH2)]+ + H2O
what final equilibrium is set up when even more OH- ions are added to aluminium hexaaqua ion
[Al(H2O)4(OH2)]+ + OH- <> [Al(H2O)3(OH)3] + H2O
why is the white precipitate formed from the final equilibrium of aluminium hexaaqua ion insoluble and why does it precipitate out
its neutral
overall equation for equilibrium of hexaagua ion
[Al(H2O)6]3+ +3OH- > [Al(H2O)3(OH3)] + 3H2O
amphoteric
species that can act as an acid or base
equation aluminium hydroxide reacting with acid
[Al(H2O)3(OH)3] + H+ > [Al(H2O)6]3+
simplified: Al(OH3) + H+ > Al3+ + 3H2O
what does the white precipitate of aluminium hydroxide dissolve to form
colourless solution
equation aluminium hydroxide reacting with base
[Al(H2O)3(OH)3] + OH- > [Al(H2O)2(OH)4]- + H2O
simplified: Al(OH)3 + OH- > Al(OH)4-
