Period 3 Yay Flashcards
Heat Na in dry Cl2 (g)
Reaction: vigorous? Flame? Eqn?
VERY vigorous burns with bright orange 🍊🍊🍊 flame 🔥🔥🔥
2Na (s) + Cl2 (g) -> 2NaCl(s)
Heat Mg with dry O2 (g)
Reaction: vigorous? Flame?
Very vigorous, white flame
Heating Na in dry O2(g)
Reaction - vigorous? Flame? Products?
Very vigorous
Burns with orange flame
4Na(s) + O2 (g) -> 2Na2O (s)
Sodium peroxide also produced: 2Na (s) + O2(g) -> Na2O2 (s)
Heat Mg with dry Cl2 (g) what do u get?
Vigorous reaction, burns with an intense white flame 💿💿💿💿
Mg (s) + Cl2 (g) -> MgCl(s)
Heat Al with dry O2 (g) ?
Very vigorous reaction at first, forming an inert Al2O3 (s) layer on the metal surface which prevents further reaction
4Al(s)+ 3O2 (g) -> 2Al2O3 (s)
Heat Al with dry Cl2 (g)
Vigorous reaction
2Al (s) + 3Cl2 (g) -> 2AlCl3 (s)
Si heat with dry O2 (g)
Slow reaction; needs to be strongly heated to about 400 degrees to form SiO2.
Si (s) + O2 (g) -> SiO2 (s)
Si heat with dry Cl2 (g)
Slow reaction
Si (s) + 2Cl2 (g) -> SiCl4 (l)
P4 (s) heat with dry o2 (g)
Vigorous? Flame?
In limited and in excess?
Vigorous reaction burns with white flame
In limited O2: P4 (s) + 3O2 (g) -> P4O6 (s)
In excess O2: P4 (s) + 5O2 (g) -> P4O10 (s)
P4 (s) heat with Cl2 (g)
Speed?
Excess and limited Cl2(g)?
Slow reaction
Limited Cl2: P4 (s) + 6Cl2 (g) -> 4PCl3 (l)
Excess Cl2: P4 (s) + 10Cl2 (g) -> 4PCl5 (s)
Heat S with dry O2 (g)
Vigorous reaction burns with pale blue flame
S (s) + O2 (g) -> SO2 (g)
SO2 reacts further with O2 to form SO3
2SO2 (g) + O2 (g) 2SO3 (g)
What is the trend in chlorides across period 3 in terms of structure?
Nacl and mgcl2 are solids, giant ionic high mp large amount of energy required to overcome strong electrostatic attraction between metal cations and chloride ions
Alcl3 (s) Sicl4 (l) Pcl5(s) Pcl3 (l)
Are simple covalents small amount of energy required to overcome the weak VDW forces between the discrete molecules
Trend of chlorides pH across period 3?
Na Mg Al Si P
7 6.5 3 2 2
Why oxidation numbers of Period 3 elements in chlorides always positive?
Chlorine more electronegative than the rest of the period 3 elements.
S does not form SCl6 even though it has energetically accessible vacant 3d orbitals. Why?
Steric hindrance - repulsion between electron clouds of the Cl atoms about the Central S atom as well as repulsion between bonding electrons.
However SF6 exists due to smaller size of F atom compared to the Cl atom.
Reaction of chlorides with water
NaCl (s) dissolves _________ in water to form ______ solution (pH = _)
Only _________ of ions (through ion-dipole interactions) takes place and __________ of Na+ does not occur as Na+ has low charge density, low polarising power
Readily Neutral 7 Hydration Hydrolysis
NaCl (s) -> Na+ (aq) + Cl- (aq)
Reaction of chlorides with water
MgCl2 dissolves _________ in water to form a w______ a_____ solution (pH = 6.5)
BOTH h________ of ions AND partial ___________ of Mg2+ (aq) occurs. Hydrolysis occurs due to polarisation of water molecules by the Mg2+ ion.
Readily
Weakly acidic
Hydration
Partial hydrolysis
- extent of hydrolysis less than that of Al3+ as Mg2+ has lower charge density than Al3+
2 eqns
Reaction of chlorides with water
AlCl3 (s) dissolves ________ in water to form an a______ solution (pH = 3) both hydration of ions and S___________ HYDROLYSIS of Al3+ (aq) occurs.
Due to high c______ d________, Al3+ is highly p________ and weakens the O-H bonds in complexing water molecules causing O-H bonds to break and release hydrogen ions
Readily Acidic solution SUBSTANTIAL HYDROLYSIS High charge density Highly polarising
2 eqns im lazy type
Reaction of chlorides with water
SiCl4 (l) dissolves in water to form s_______ acidic solution (pH=?) and a w_____ c__________ solid SiO2.
SiCl4 undergoes h_________ in water. This is because Si atom in SiCl4 has e____________ a____________ vacant 3d orbital for d______ bonding with water molecules.
Strongly acidic!!! pH =2
White crystalline
Hydrolysis
Energetically accessible vacant 3d orbital
Dative bonding
SiCl4 (l) + 2H2O (l) -> SiO2 (s) + 4HCl (aq)
PCl5 (s) and PCl3 (l) undergo h________ in water to give strongly a_______ solutions (pH=2).
P atom able to use its e________ accessible vacant 3d orbitals for d_______ bonding with water molecules.
Hydrolysis
Acidic
Energetically accessible
Dative
Trend across period 3 elements for OXIDES?
Na2O (s) MgO (s) Al2O3 (s)
Ionic 📷📷📷📷 ionic with covalent character
Giant ionic lattice
SiO2 (s) giant covalent
P4O10 (s) P4O6 (s) simple covalent
Trend of acid/base behaviour of period 3 oxides across period?
Basic to acidic
Basic = Na2O (s) and MgO (s)
Amphoteric = Al2O3 (s)
Acidic = SiO2 (s), P4O10 (s) P4O6 (s) SO3 (l) SO2 (g)
which oxides are basic?
Na2O
MgO
Which oxide is amphoteric?
al2O3 (s)
Which oxides are acidic?
SiO2 (s) p4O10 (s) P4O6 (s) so3 (l) So2 (g)
PH of oxides in solution across period?
12 8 7 7 2 2 2
Why are oxidation numbers of period 3 elements in their oxides always positive?
Oxygen more electronegative than their period 3 elements.
Acid / base behaviour of oxides 👛
Na2O (ionic) and BASIC, reacts v_________ with water to form ______(aq) which is strongly alkaline (pH = 12)
Na2O(s) + H2O (l) -> 2NaOH (aq)
Vigorously
NaOH
Acid / base behaviour of oxides 👛
Na2O (s) reacts with acid (because it is basic) to form s____ and ______.
Salt and water
Na2O (s) + 2H+ (aq) -> 2Na+ (aq) + H2O (l)
Acid / base behaviour of oxides 👛
MgO (s) reacts with water to form Mg(OH)2 (s) which d_________ sp________ in water to give a w_________ al_______ (pH =8) solution.
Dissolves sparingly
Weakly alkaline
MgO(s) + H2O (l) -> Mg(OH)2 (s)
Mg(OH)2 (s) Mg2+ (aq) + 2OH- (aq) (dissolves)
Acid / base behaviour of oxides 👛
MgO (s) reacts with acid (because it is BASIC) to form s____ and ______
Salt and water
MgO (s) + 2H+ (aq) -> Mg2+ (aq) + H2O (l)
Acid / base behaviour of oxides 👛
Al2O3 (ionic) (amphoteric) is _______ in water due to large ____________ of its lattice energy.
pH = 7
Insoluble
Magnitude
Energy released during hydration of ions through formation of ion-dipole interaction is insufficient to compensate for energy required to overcome strong electrostatic forces of attraction between Al3+ ions and O2- ions to break down giant ionic lattice. Since oxide does not dissolve in water it will not affect pH.
Acid / base behaviour of oxides 👛
Al2O3 (s) AMPHOTERIC, reacts with both acid and alkali to form ______ and ______.
With acid: Al2O3 (s) + _____ (aq) -> 2Al3+ (aq) + 3H2O (l)
With base: Al2O3 (s) + 2___- (aq) + 3H2O (l) -> 2[Al(OH)4]- (aq)
Salt and water.
H+
OH-
Acid / base behaviour of oxides 👛
SiO2 (covalent) (acidic)
_______ in water as large amount of energy required to break many _______ _________ bonds in the ______ covalent structure. Since oxide does not dissolve in water it will not affect pH (=7)
Insoluble
Strong covalent bonds
Giant covalent structure
Acid / base behaviour of oxides 👛
SiO2 (s) reacts with concentrated _______ to form salts and water
ALKALI!! Cause SiO2 is acidic.
SiO2 (s) + 2OH- (aq) -> SiO3^2- (aq) + H2O (l)
Acid / base behaviour of oxides 👛
P4O6 (s) and P4O10 (s) are covalent and acidic.
They react with water to give an a_____ solution. (Ph=?)
Acidic, 2.
P4O10 (s) + 6H2O (l) -> 4H3PO4 (aq)
P4O6 (s) + 6H2O (l) -> 4H3PO3 (aq)
Acid / base behaviour of oxides 👛
P4O6 (s) and P4O10 (s) are covalent and acidic.
They react with ALKALI to form salt and water.
P4O10 (s) + 12OH- (aq) -> 4PO4^3- (aq) + 6H2O (l)
P4O6 (s) + 8OH- (aq) -> 4HPO3^2- (aq) + 2H2O
Acid / base behaviour of oxides 👛
SO2 (g) and SO3 (s) are covalent and acidic.
They react with water to give acidic solutions (pH=2)
SO2 (g) + H2O (l) -> H2SO3 (aq)
SO3 (g) + H2O (l) -> H2SO4 (aq)
Acid / base behaviour of oxides 👛
SO2 (g) and SO3 (s) are covalent and acidic.
They react with ALKALI to form salt and water.
SO2 (g) + 2OH- (aq) -> SO3^2- (aq) + H2O (l)
SO3 (l) + 2OH- (aq) -> SO4^2- (aq) + H2O (l)
What is an amphoteric hydroxide?
Al(OH)3
Trend across period 3 of hydroxides in terms of bonding and acidity?
NaOH and Mg(OH)2 are ionic and basic
Al(OH)3 is ionic and AMPHOTERIC
Si(OH)4 = SiO2.2H2O is covalent and acidic
Generally, ionic oxides / hydroxides are ______; covalent oxides / hydroxides are ______.
________ and __________ are amphoteric.
BASIC; ACIDIC
Al2O3 and Al(OH)3
What are the two oxides that are insoluble in water?
Al2O3 (s) and SiO2 (s)
