13.1 - Trends Across Period 3

13.1 - Trends Across Period 3 13.1.1 - Explain the physical states (under standards conditions) and electrical conductivity (in the molten state) of the chlorides and oxides of the elements in period 3 in terms of their bonding and structure Sodium Chloride

Sodium Oxide

Physical State

Physical State



Ionic Bonding



Ionic Bonding



High melting and Boiling Point



High melting and Boiling Point



Solid under standard conditions



Solid under standard conditions



Conduct electricity in liquid state



Conduct electricity in liquid state

Electrical Conductivity

Electrical Conductivity



Conducts electricity in liquid state



Conducts electricity in liquid state



Electrolyte - decomposes into



Electrolyte - decomposes into

constituent elements

constituent elements

Magnesium Chloride

Magnesium Oxide

Physical State

Physical State



Ionic Bonding



Ionic Bonding



High melting and Boiling Point



High melting and Boiling Point



Solid under standard conditions



Solid under standard conditions



Conduct electricity in liquid state



Conduct electricity in liquid state

Electrical Conductivity

Electrical Conductivity



Conducts electricity in liquid state



Conducts electricity in liquid state



Electrolyte - decomposes into



Electrolyte - decomposes into

constituent elements

constituent elements

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Aluminium Chloride

Aluminium Oxide

Physical State

Physical State



Ionic layer lattice



Sublimes at 178oC



Under reduced pressure will melt at 192.5oC

Electrical Conductivity 



Very high melting point because ionic

Electrical Conductivity 

Conducts electricity well



Can be electrolysed to produce

Becomes a covalently bonded

aluminium metal

molecule 

Forms dimers



Will not melt under standard conditions



At reduced pressure, will melt, having high conductivity just before the melting point



Does not conduct electricity when molten because of covalent structure

Silicon Chloride

Silicon Dioxide

Physical State

Physical State



Discrete Covalent Molecules



Covalent network lattice



Weak Van der Waals forces



Single covalent bonds

between molecules



High melting and boiling points

Liquid under standard conditions



Solid under standard conditions



Electrical Conductivity 

Non-polar



Does not conduct electricity as a liquid

Electrical Conductivity 

Poor conductor of electricity as a liquid



Natural coating on surface is a valuable electrical insulator

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Phosphorous Chloride

Phosphorous Oxide

Physical State

Physical State



Covalent



Weak Van der Waals forces



PCl5 is non-polar and has stronger



P4O10 has stronger bonds because it

Van der Waals forces, increasing

is larger 

melting and boiling points 



PCl3 is slightly polar and liquid under standard conditions

Covalent



Do not conduct electricity

P4O6 has weaker bonds because it is smaller 

Electrical Conductivity 

Powdery

Waxy

Electrical Conductivity 

Covalently bonded



Do not conduct electricity in the liquid state

Sulfur Dichloride

Sulfur Oxides

Physical State

Physical State



Liquid under standard conditions

Electrical Conductivity 



SO2 gas under standard conditions



SO3 liquid under standard

Does not conduct electricity

conditions Electrical Conductivity 

Do not conduct electricity

Chlorine Gas

Chlorine Oxide

Physical State





Non-polar molecules



Very weak Van der Waals forces



Boiling point -34oC

Physical State 

 

Does not conduct electricity



Gas

Cl2O7 is unstable liquid 

Electrical Conductivity 

Cl2O is easily ignited

Weak Van der Waals forces

Electrical Conductivity 

Do not conduct electricity

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Summary of Chlorides NaCl

MgCl2

AlCl3

SiCl4

PCl5

SCl2

Cl2

Ionic 714

Ionic 178

Covalent -70

Covalent 179

Covalent -121

Covalent -101

Solid

Solid

Liquid

Solid

Liquid

Gas

MgO

Al2O3

SiO2

P5O10/ P4O6

SO3/ SO2

Cl2O7/ Cl2O

Bonding Ionic

Ionic

Ionic

Covalent

Covalent

Covalent

Melting Point State

1275

2852

2054

Covalent network lattice 1610

24

17

-92

Solid

Solid

Solid

Solid

Solid/ Liquid

Liquid/ Gas

Liquid/ Gas

Bonding Ionic Melting 801 Point State Solid Summary of Oxides Na2O

13.1.2 - Describe the reactions of chlorine and the chlorides referred to in 13.1.1 with water

NaCl dissolves in water to form a neutral solution. The ions dissociate and assimilate into the solution. There is ion dipole bonding to attract water.

MgCl forms a slightly acidic solution.

The magnesium may also form dative bonds with the water, making the solution slightly acidic.

AlCl3 forms a highly acidic solution. The reaction with water causes spitting and acid fumes

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This is a very acidic solution, with dative bonds between the aluminium and the water molecules.

The aluminium ion acts as a Bronsted-Lowry acid

This forms a highly acidic solution

The HCl dissolves to form a highly acidic solution

Forms a highly acidic solution

Reacts to form chlorine water

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