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AS Chemistry - Physical > 3.1.3 - Bonding > Flashcards

3.1.3 - Bonding Flashcards

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1
Q

Define ‘ionic bonding’

A

Ionic bonding: electrostatic attraction between oppositely charged ions in a lattice.

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2
Q

Describe the physical features of ionic substances x3

A

Ionic substances are always solid at room temperature, brittle and shatter easily.

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3
Q

How do you strengthen ionic bonding?

A
  • Greater charge on the ions.
  • Smaller ions.
  • > Higher charge density
  • > Stronger ionic bonding
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4
Q

Ionic compounds involve a metal and metal. True/false?

A

False: Ionic compounds involve a metal and non-metal.

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5
Q

When can ionic compounds conduct electricity and why?

A

Ionic compounds cannot conduct electricity when solid, but can when molten/dissolved in water, as ions can move to carry a charge.

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6
Q

Do ionic substances have low or high mpts/bpts? Why?

A

Because ionic compounds are in a giant ionic lattice, there are strong electrostatic forces of attraction between oppositely charged ions acting in all directions, thus they have high mpts/bpts.

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7
Q

When is an ionic subtance purely ionic in bonding?

A

With the Pauling’s Scale, a difference of 1.7 or over between the elements means that the bond is purely ionic.

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8
Q

Define ‘covalent bond’

A

A chemical bond formed by the sharing of pairs of electrons between atoms.

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9
Q

‘A single covalent bond contains a ______ ______ of electrons. Multiple bonds contain ________ pairs of electrons.’


A

‘A single covalent bond contains a shared pair of electrons. Multiple bonds contain multiple pairs of electrons.’


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10
Q

What is it called when one atom donates both electrons in the shared electron pair of a covalent bond? Example?

A

‘A co-ordinate (dative covalent) bond contains a shared pair of electrons with both electrons supplied by one atom.’ E.g. NH4+

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11
Q

Covalent bonding occurs…?

A

Between non-metals.

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12
Q

Simple molecular substances have a ______ structure

A

Molecular (non-lattice) structure.

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13
Q

Do simple molecular substances have low or high mpts/bpts? Why?

A

Low, because only weak IMFs exist between molecules, which require little energy to overcome and break.

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14
Q

Can simple molecular substances conduct electricity and why?

A

No - no delocalised electrons or ions to move and carry the charge.

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15
Q

What is a dimer? Example?

A

A ‘dimer’ is 2 of the same molecule bonded together in order to satisfy the electron arrangements of each atom, e.g. AlCl3

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16
Q

How are atoms in a simple molecular substance held together?

A

Covalent bonds: atoms are held together by each nucleus pulling on the electrons.

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17
Q

Which are stronger, covalent bonds or dative covalent/coordinate bonds?

A

In dative covalent bonds, the 2 electrons still come under equal influence of the forces of attraction to the nuclei, thus dative covalent bonds are of the same strength as covalent bonds.

18
Q

Define ‘metallic bonding’.

A

‘Metallic bonding involves attraction between delocalised electrons and positive ions arranged in a lattice.’

19
Q

Do metals have high/low bpt/mpts and why?

A

HIGH - Metallic bonds are strong and a lot of energy is needed to break them. This is why metals have high melting points and boiling points. The bonds are strong attraction between closely packed positive metal ions and a ‘sea’ of delocalised electrons.

20
Q

When do metals conduct electricity and why?

A

Both when solid and dissolved/molten, as delocalised electrons can move through the structure and carry a charge.’When a potential difference is applied, they will move together, allowing an electric current to flow through the metal.’

21
Q

How do we get stronger metallic bonding and why?

A
  • Smaller the metal ions
  • Greater the charge on the ions (more delocalised outer shell electrons)
  • > Stronger attraction between the ions and electrons (usually). = This is due to a greater charge density within the structure.
22
Q

Solubility of metals in water?

A

Insoluble.

23
Q

Solubility of macromolecules in water?

A

Insoluble.

24
Q

Mpts/bpts of macromolecules and why?

A

High - strong covalent bonds in a giant structure.

25
Q

Conductivity of electricity in macromolecules when solid?

A

Diamond - X
Graphite - YES, due to one delocalised electron per carbon that can move along the planes of carbon atoms, between the layers.

26
Q

Conductivity of electricity in macromolecules when molten?

A

Poor.

27
Q

What physical state do most simple molecular substances take at room temp?

A

Liquid/gas.

28
Q

Physical properties of metals? x3

A
  • Shiny.
  • Crystalline solids (at room temp).
  • Malleable (as the positive ions in the lattice are all identical, so the planes of ions can easily slide over one another).
29
Q

A change of state directly from solid to gas is called…?

A

A change of state directly from solid to gas is called ‘sublimation’.

30
Q

Define ‘enthalpy’.

A

Enthalpy is the amount of heat content used or released in a system at constant pressure.

31
Q

Solid -> liquid: latent heat of ________

A

Latent heat of fusion

32
Q

Liquid -> gas: latent heat of ________

A

Latent heat of vaporisation

33
Q

Lone pair–lone pair repulsion is ________ than lone pair–bond pair repulsion, which is ________ than bond pair–bond pair repulsion:
lp-lp __ lp-bp __ bp-bp.

A

Lone pair–lone pair repulsion is greater than lone pair–bond pair repulsion, which is greater than bond pair–bond pair repulsion:
lp-lp> lp-bp > bp-bp.

34
Q

Define ‘electronegativity’.

A

Electronegativity is the power of an atom to attract the pair of electrons in a covalent bond.

35
Q

The electron distribution in a covalent bond between elements with different electronegativities will be _________.

A

The electron distribution in a covalent bond between elements with different electronegativities will be unsymmetrical.

36
Q

Order the strength of all IMFs

A

Strength: H-bonds > permanent dp-dp > vdWs’

37
Q

Which IMF is present between ALL molecules?

A

van der Waals’ forces

38
Q

Synonyms for van der Waals’ forces?

A

van der Waals’ forces/Dispersion forces/London forces

39
Q

How do you draw/display the different IMFs?

A

All dashed lines!

40
Q

What happens to the IMFs between H2O molecules when ice is formed, and at what temperature?

A

Below 4degrees C, molecules of H2O orientate themselves to form as many hydrogen bonds as possible. This causes ice to have a regular lattice structure with gaps between water molecules, meaning ice has a lower density than liquid water.

41
Q

Why does hydrogen bonding occur? x4

A
  • Hydrogen is covalently bonded to a very electronegative element: oxygen/fluorine/nitrogen.
  • This atom pulls the covalently bonded electron pair closer to its nucleus, and away from the hydrogen atom.
  • The hydrogen atom is then left with a bare nucleus, a partial positive charge and a very high charge density (due to its very small size).
  • This results in a hydrogen bond between the hydrogen and a lone pair on a neighbouring oxygen/fluorine/nitrogen atom.

AS Chemistry - Physical (8 decks)

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