Period 3 Yay Flashcards by Alexea Ong

Heat Na in dry Cl2 (g)

Reaction: vigorous? Flame? Eqn?

VERY vigorous burns with bright orange 🍊🍊🍊 flame 🔥🔥🔥

2Na (s) + Cl2 (g) -> 2NaCl(s)

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Heat Mg with dry O2 (g)

Reaction: vigorous? Flame?

Very vigorous, white flame

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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)

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Heat Mg with dry Cl2 (g) what do u get?

Vigorous reaction, burns with an intense white flame 💿💿💿💿

Mg (s) + Cl2 (g) -> MgCl(s)

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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)

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Heat Al with dry Cl2 (g)

Vigorous reaction

2Al (s) + 3Cl2 (g) -> 2AlCl3 (s)

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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)

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Si heat with dry Cl2 (g)

Slow reaction

Si (s) + 2Cl2 (g) -> SiCl4 (l)

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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)

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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)

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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)

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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

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Trend of chlorides pH across period 3?

Na Mg Al Si P

7 6.5 3 2 2

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Why oxidation numbers of Period 3 elements in chlorides always positive?

Chlorine more electronegative than the rest of the period 3 elements.

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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.

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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)

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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

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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

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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.

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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.

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Hydrolysis
Acidic
Energetically accessible
Dative

Trend across period 3 elements for OXIDES?

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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?

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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?

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Na2O

MgO

Which oxide is amphoteric?

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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)

Period 3 Yay Flashcards

(43 cards)