Ionic bonds and Ionic solids

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Why do ionic solids form lattices?
Due to the electrostatic attraction between the ions(elements with very different electron affinities); there is a large reduction in E_p as the ions are brought into close proximity.So a lattice is more stable than the the separate ions
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Give one definition of lattice energy (+ve)
The energy required to break a part an ionic solid and convert its component atoms into gaseous ions.
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Give another definition of lattice energy (-ve)
The energy released when gaseous ions bond to form an ionic solid.
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What is the lattice energy used for?
It is used to measure the stability of ionic solids (however it cannot be measured directly)
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What are the two ways of evaluating lattice energy?
1) the electrostatic attractive force between ions of charge Z_1 and Z_2 (Coulomb's law); 2)The repulsion between the negatively charged electron clouds as ions are brought together (B/r^n)
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Give the equation for the total energy involved with ionic bonds
U_total = (Z_1*Z_2*e^2)/(4*pi*epsilon_0*r) +B/r^n (where B and n are constants)
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What is the Born-Lande equation?
U_lattice =(N_A*M*Z_1*Z_2*e^2)/(4*pi*epsilon_0*r_0)*(1-1/n)--> r_0: equilibrium separation;Z:numeric charge;n:Born exponent;M:Madelung constant[dependent on crystal structure]
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Describe the relationship between Lattice energy and ionic radius
The greater the ionic radius the lower the lattice energy.(assuming that ions are point charges; r_0 is larger)
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Describe the relationship between Lattice energy and ionic charge
The greater the ionic charge the higher the lattice energy (stronger attraction between ions)
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Define Hess's law
ΔH∘f for a specific reaction is equal to the sum of the heats of reaction for any set of reactions which in sum are equivalent to the overall reaction.
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Describe the relationship between Lattice energy and melting temperature
They are proportional; the greater the lattice energy the greater the melting point
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Describe the relationship between Lattice energy and solubility
The greater the lattice energy the smaller/lower the solubility (in water)
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Describe the relationship between Lattice energy and hardness
The higher the lattice energy the greater the hardness. As hardness is the resistance to indentation (plastic deformation) it is directly related to how tightly the ions are held together.
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Card 2

Front

Give one definition of lattice energy (+ve)

Back

The energy required to break a part an ionic solid and convert its component atoms into gaseous ions.

Card 3

Front

Give another definition of lattice energy (-ve)

Back

Preview of the front of card 3

Card 4

Front

What is the lattice energy used for?

Back

Preview of the front of card 4

Card 5

Front

What are the two ways of evaluating lattice energy?

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