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Higher Chemistry > UNIT 1 > Flashcards

UNIT 1 Flashcards

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1
Q

What does a higher density mean?

A

The more closely packed the particles are

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2
Q

Why do gaseous elements have lower densities?

A

Because their particles are packed far apart

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3
Q

Why do solid elements have higher densities?

A

Because their particles are packed closely together

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4
Q

What does it mean for the bonds if the particles are packed together?

A

The bonds between the particles are likely to be stronger

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5
Q

What happens to the density of metals going across a period?

A

The density increases

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6
Q

What happens to the density of metals going down a group?

A

The density increases

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7
Q

What happens to the density of non metals going across a period?

A

There is no real pattern

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8
Q

What happens to the density of non metals going down a group?

A

The density increases

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9
Q

What is metallic bonding?

A

Metallic bonding is the strong electrostatic force of attraction between the positive charged ions

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10
Q

What are intramolecular forces?

A

The forces that hold atoms together within a molecule

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11
Q

What are intermolecular forces?

A

The forces that exist between molecules

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12
Q

What is covalent radius?

A

A measure of the size of the atom

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13
Q

What happens to covalent radius going across a period?

A

The covalent radius decreases

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14
Q

Why does covalent radius decrease going across a period?

A

As you from from left to right, you add a proton to the nucleus and an electron to the outermost energy level

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15
Q

What happens to covalent radius going down a group?

A

The covalent radius increases

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16
Q

Why does covalent radius increase going down a group?

A

An extra outer electron shell is added every time making it further away from the nucleus

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17
Q

What happens to atomic size across a period?

A

The atomic size decreases

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18
Q

Why does atomic size decrease going across a period?

A

A proton is added each time, increasing the nuclear charge

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19
Q

What happens to atomic size going down a group?

A

The atomic size increases

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20
Q

Why does atomic size increase going down a group?

A

This is due to an outer shell of electrons being added each time

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21
Q

What is ionisation energy?

A

The energy required to remove one mole of electrons from one mole of atoms in the gaseous state

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22
Q

What happens to ionisation energy going across a period?

A

The ionisation energy increases

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23
Q

Why does ionisation energy increase across a period?

A

Due to increasing nuclear charge

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24
Q

What happens to ionisation energy going down a group?

A

The ionisation energy decreases

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25
Q

Why does ionisation energy decrease going down a group?

A

Due to the electrons being further away from the nucleus and the shielding effect from inner electrons

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26
Q

What happens in the second ionisation energy?

A

Negative electrons are being removed from positive ions rather than neutral atoms

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27
Q

What is electronegativity?

A

A measure of the attraction an atom has for the electrons involved in a bond

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28
Q

What happens to electronegativity going across a period

A

The electronegativity increases

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29
Q

Why does the electronegativity increase going across a period?

A

Because the charge in the nucleus increases across a period

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30
Q

What happens to the electronegativity going down a group?

A

The electronegativity decreases

31
Q

Why does electronegativity decrease going down a group?

A

Because the atoms have a bigger radius

32
Q

What is the electronegativity difference for pure covalent?

A

< 0.4

33
Q

What is the electronegativity difference for polar covalent?

A

Between 0.4 and 1.8

34
Q

What is the electronegativity difference for ionic?

A

> 1.8

35
Q

When does polar covalent arise?

A

When there is a difference in electronegativity between atoms in a bond

36
Q

How is a negative dipole formed?

A

The atom with the higher electronegativity will pull the bonding electrons closer to itself

37
Q

Where does hydrogen bonding occur?

A

Between molecules of compounds that are highly electronegative like N, O or F

38
Q

Why do boiling points increase when molecular size increases?

A

Because of Van der Waal’s forces

39
Q

What does hydrogen bonding in solid water give rise to?

A

An open structure

40
Q

Why is ice less dense than liquid water and float to the top?

A

Because it has an open structure

41
Q

When does a permanent dipole exist?

A

If the molecule has a permanent uneven distribution of charge

42
Q

How is solubility of a substance determined?

A

By it’s bonding

43
Q

What can polar substances dissolve in?

A

Other polar substances

44
Q

What can non-polar substances dissolve in?

A

Other non-polar substances

45
Q

What does diatomic molecule bonding exist in?

A

Diatomic molecules

46
Q

What are the forces like in diatomic molecules?

A

Forces within the molecules are strong covalent bonds whereas forces between the molecules are weak Van der Waal’s

47
Q

What are melting and boiling points like in diatomic molecules?

A

Melting and boiling points are low

48
Q

What are examples of elements that contain diatomic molecules?

A
  • Hydrogen
  • Nitrogen
  • Fluorine
  • Oxygen
  • Chlorine
49
Q

What holds the atoms together in covalent network bonding?

A

Strong covalent bonds

50
Q

What are melting and boiling points like in covalent network?

A

Very high melting and boiling points

51
Q

What are examples of elements that have covalent network?

A
  • Boron
  • Carbon
  • Silicon
52
Q

What are examples of elements with covalent molecular?

A
  • Phosphorus
  • Sulfur
53
Q

What do covalent molecular molecules produce?

A

Larger Van der Waal’s forces than diatomic molecules because they have many electrons

54
Q

What does the stonger temporary dipoles do to the melting and boiling points in covalent molecular substances?

A

Raises melting and boiling points making them solids at room temperature

55
Q

What does delocalised electrons do to metallic bonding elements?

A

Makes them good conductors

56
Q

What are examples of metallic bonding elements?

A
  • Lithium
  • Sodium
  • Magnesium
  • Potassium
  • Calcium
57
Q

What exists between the atoms in monatomic elements?

A

Weak Van der Waal’s forces

58
Q

What type of melting and boiling points are in monatomic elements?

A

Very low melting and boiling points

59
Q

What are examples of monatomic elements?

A
  • Helium
  • Neon
  • Argon
60
Q

How are London Dispersion Forces caused?

A

By the uneven distribution of the constantly moving electrons around the nuclei of the atoms. This then causes the formation of temporary dipoles on the atoms. The atoms then attract each other

61
Q

Why do London Dispersion Forces increase?

A

Because as you go down the group, the number of electrons increases

62
Q

What is oxidation?

A

Loss of electrons

63
Q

What is reduction?

A

Gain of electrons

64
Q

What is an oxidising agent?

A

A chemical species that brings about an oxidation in something else but is itself reduced

65
Q

What do oxidising elements have and why?

A

Elements that are good oxidising agents generally have high electronegativity as they need to be good at accepting electrons from other substances

66
Q

What is a reducing agent?

A

A chemical species that brings about a reduction in something else but is itself oxidised

67
Q

What do reducing elements usually have and why?

A

Elements that are good reducing agents generally have low ionisation energies as they need to be good at donating electrons to other substances

68
Q

What is chromatography?

A

A useful technique to separate molecules in a mixture

69
Q

What is chromatography used for?

A

Fingerprinting, defecting bombs in airports, identify drugs and alcohol

70
Q

How do you work out Rf value?

A

Rf = distance from the bass line to the spot / distance from the bass line to the solvent front

71
Q

What is the stationary phase?

A

Chromatography paper

72
Q

What is the mobile phase?

A

Suitable solvent (Water, Ethanol, Organic Solvent)

73
Q

What is the separation method?

A

As the solvent moves up the paper, it dissolves the sample. The more soluble the sample, the further up the paper it will travel

Higher Chemistry (3 decks)

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