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chemistry > S2.1 - ionic model > Flashcards

S2.1 - ionic model Flashcards

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1
Q

What are anions and cations?

A

Anions - negative ions that have gained electrons
Cations - positive ions that have lost electrons

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2
Q

What is an ion?

A

Ion - charged atoms that have gained or lost electrons.

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3
Q

Why do metal atoms experience a smaller ENC?

A

Metals experience a smaller ENC due to increased atomic size due to the large number of shells and shielding so there is a weaker attraction.

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4
Q

Why do metal ions form positive ions?

A

Metal atoms form positive ions as they have low ionization energies.

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5
Q

How is sodium chloride formed?

A

One electron is transferred from sodium to chloride.

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6
Q

How does attraction between water ions increase?

A

Attraction increases with ionic charge but removing multiple electrons has an energy cost.

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7
Q

What ions can Na form?

A

Na+ and Na3+ readily but not Na2+ and Na4+

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8
Q

Why are anions more attractive with increased charge?

A

Anions are more attractive with increased charge as they readily accept an electron ti their outer energy level.

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9
Q

Why is addition of electrons harder with increased charge?

A

There is increasing negative charge of the ion due to increased electron-electron repulsion.

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10
Q

Why are nobles gases unreactive?

A

Noble gases are unreactive due to their high ionization energies and complete energy levels, so adding an electron would need to add an extra shell which would be lost.

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11
Q

What are properties of transition metals?

A

Transition metals have a wide range of oxidation states that is related to successive ionization energy patterns.

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12
Q

What happens when ions have a charge greater than +3?

A

Ions with a charge greater than +3 show a covalent character as they have a large charge density as they polarize negative ions and increase the covalent character of the compound.

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13
Q

Why is the formation of Ca3+ unfavourable?

A

3rd ionization energy prohibits further electron loss.

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14
Q

How can you determine maximum oxidation states?

A

The maximum oxidation state is reached when the linear pattern ends.

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15
Q

What is a polyatomic ion?

A

Ions made up of more than 1 atom that have lost or gained electrons.

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16
Q

What type of bonding is present in polyatomic ions?

A

Ionic bonding

17
Q

What is an ionic bond?

A

Ionic bond - attraction between positive metal ion and negative electron.

18
Q

What is the structure for ionic compounds?

A

Giant ionic lattic

19
Q

What is the structure of NaCl?

A

Cl- = has a smaller radius due to larger ENC
Na+ = has a larger radius due to smaller ENC

20
Q

What is a co-ordination number?

A

Number of atoms that surround individual atoms in a lattice.

21
Q

What is lattice enthalpy?

A

Lattice enthalpy - energy needed to break or make the ionic bond in a lattice.
- Measure of the strength of a bond.

22
Q

How can you increase lattice enthalpy?

A
  • Increase in ionic charge
  • Decrease in ionic radii
  • Change in charge density
23
Q

Why do ionic compounds have high melting and boiling points?

A

Ionic compounds have high melting and boiling points as they have a strong electrostatic attraction between electrons and positive ions.

24
Q

How does charge affect melting and boiling points?

A

Larger charge = Higher melting and boiling point as there is a higher electrostatic attraction and therefore a stronger bond.

25
Q

Why are ionic compounds non-volatile?

A

Ionic compounds are non-volatile as they are held in a lattice, meaning that there are no free molecules to move away and break from the structure, which would require high amounts of energy.

26
Q

When are ionic compounds soluble?

A

Ionic compounds are soluble in polar solvents such as water since like substances dissolve.

27
Q

How can you tell if a substance has dissolved or not?

A

Dissolved - if the electrostatic attraction between ions is weaker than water’s attraction to them.
Not dissolved - if the electrostatic attraction between ions is stronger than water’s attraction to them.

28
Q

What does hydrated mean?

A

Hydrated - when ions are surrounded by water molecules.

29
Q

What does solvated mean?

A

Solvated - when ions are surrounded by other solvent molecules.

30
Q

Why do ionic compounds conduct electricity?

A

Ionic compounds can conduct electricity as they have delocalised electrons which can move around the structure and carry charge.

31
Q

Why are ionic compounds brittle?

A

Ionic compounds are brittle as crystals break when a force is applied since the pressure forces like charges together so that they repel each other to the point of breaking.

32
Q

When is something ionic, covalent or polar covalent?

A

Ionic - difference in electronegativity > 1.8
Covalent - difference in electronegativity < 0.4
Polar covalent - difference in electronegativity is between 0.4 and 1.8.

33
Q

Why are period 3 oxides less ionic across?

A

It is shown by a decrease in melting points and a decrease in the ability to conduct electricity in the molten state.

34
Q

How do you work out % ionic character?

A

% ionic character = (difference in electronegativity / 3.2) x 100

35
Q

How do you calculate lattice enthalpy for 1 mole of ion pairs?

A

Lattice enthalpy for 1 mole = (Knm / Rm+ + Rx-)
K - constant for a structure that takes into account one of the many ion interactions and depends on the geometry of the lattice.
n and m - magnitude of the charge of the ions
Rm+ and Rx- - ionic radii

36
Q

What is the relationship between energy needed to separate 2 ions and ionic charge?

A

An increase in ionic charge increases the ionic attraction between ions and increases lattice enthalpy.

37
Q

What is the relationship between energy needed to separate 2 ions and ionic radius?

A

An increase in ionic radius of one of the ions decreases the attraction between the ions and decreases the lattice enthalpy.

38
Q

What is the relationship between energy needed to separate 2 ions and charge density?

A

The lattice enthalpy is greater for ions with a larger charge density as they have a small radius and are highly charged.

chemistry (22 decks)

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