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A Level Chemistry > Module 2 (chapter 5 and 6) - bonding and intermolecular forces > Flashcards

Module 2 (chapter 5 and 6) - bonding and intermolecular forces Flashcards

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1
Q

What is the general electron configuration

A

2.8.18.32

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2
Q

What does the number in front of sub shells mean?

A

The principle quantum level (shells)

This can be found from the row of that element on the periodic table

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3
Q

What are the rules when filling electron orbitals?

A
  • fill form bottom up with arrows going up then down
  • when there is move than one box fill along before pairing up as like charges repel
  • fill up 4d before 3P as they have very similar energy levels but loose from 4D before 3P
  • Group principle quantum levels together
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4
Q

How do you use Nobel gas configurations when filling shells?

A

Choose the previous novel gas and pit it in square brackets

-list the remaining sub shells until all electrons in the element are used

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5
Q

How is the periodic table classed into S,D,P and F blocks?

A

Based off their highest energy electrons

E.g. first two columns have their highest energy electrons in an S sub shell so they are in the S block

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6
Q

What is the general order of sub shells?

A

1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s2

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7
Q

What is an ion?

A

Positively or negatively charged atoms (covalently bonded) or groups of atoms (a molecule ion)
-they have an imbalance of protons and electrons leading to an overall charge on the particle
(E.g. atomic ions like Li+ and covalently bonded ions like Co3 2-]

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8
Q

What is relative isotopic mass?

A

(RIM) The mass of an atom of an isotope compared with 1/12 of the mass of carbon-12

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9
Q

What is relative atomic mass?

A

The weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12

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10
Q

What is the relative molecular mass?

A

The weighted mean mass of a molecule compared with 1/12 of the mass of an atom of c-12
Only applies to simple covenant molecules

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11
Q

What is relative formula mass?

A

The weighed mean mass of a formula unit compared to 1/12 of the mass of an atom of carbon-12
-can apply to iconic substances as these occur as giant lattices

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12
Q

What does a full stop in an equation mean?

A

Hydrated

-makes up structure but isn’t chemically bonded

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13
Q

Atomic number

A

Number of protons in the nucleus of the atom

Z

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14
Q

Mass number

A

The number of particles (protons and neutrons) un the nucleus of an atom
(A)

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15
Q

Isotopes

A

Atoms of the same element with the same number of protons but different number of neutrons

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16
Q

What are properties of isotopes?

A
  • sometimes extra neutrons make the nucleus unstable so it’s radioactive
  • different isotopes of the same element can have different physical properties
  • always have the same chemical properties as reactions depend on the electron structure
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17
Q

In mass spectrometry why can’t you join the peaks?

A

As there are no isotopes in between

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18
Q

In mass spectrometry why are there two clusters of peaks?

A

As some elements have more than one atom per molecule

  • when passed through an electron is knocked of the molecule giving a molecular iron
  • these can be unstable and fall apart leading to fragmentation so the two sets account for both fragmented and un-fragmented ions
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19
Q

What value to you approximate the tallest peak

A

100

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20
Q

Why can’t you predict the relative heights f the two clusters only approximate?

A

Because it is dependent on what proportion of molecular ions break up into fragments

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21
Q

In mass spectrometry what do the different lines mean?

A

They are different isotopes in proportion of their varying charges and masses

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22
Q

What the calculation to work out atomic contribution and RAM from mass spectrometry?

A

Amount/total amount x mass

Add all of these together from different isotopes for RAM

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23
Q

ionic bond

A

an electrostatic force of attraction between oppositely
charged ions. they are non directional in three dimensions
-there is a transfer of electrons

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24
Q

ion

A

an electrically charged particle formed by the loss or gain of one or more electrons from one atom or group of atoms

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25
Q

element

A

substance made of one type of atom

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26
Q

compound

A

substance made of two or more types of atoms chemically bonded together

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27
Q

molecule

A

particles made from two or more atoms chemically bonded together using covenant bonds

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28
Q

giant ionic lattice

A

structure resulting from oppositely charged ions strongly attracted in all directions

29
Q

melting and boiling point of ionic compound

A

-high melting and boiling point due to strong electrostatic forces of attraction between oppositely charged ions which means a lot of energy needed to overcome these

30
Q

solubility of ionic compounds

A

some are soluble in water (polar solvents) if the ionic lattice breaks down and if water molecules attract and surround ions

  • this is because opposite charges of salt and water ion are attracted and as this happens atoms begin to separate was water molecules surround it dissolving it
  • therefore solubility depends on the relative strength of the attractions as this has a greater effect, and solubility decreases as ionic charge increases
31
Q

electrical conductivity of ionic compounds

A

conducts electricity when molten or dissolved

  • in a solid state the ions are in a fixed position in the giant ionic lattice so there are no mobile charge carriers
  • yet when the lattice is broken down ions are now free to move as mobile charge carriers
32
Q

what is a covenant bond?

A

a strong electrostatic force of attraction between a shared pair of electrons and the nuclei of the bonded atoms
occur in:
-nonmetallic elements
-compounds of non metallic elements
-polyatomic ions
it is an overlap of atomic orbitals each containing one electron
-the bonded atoms often have outer shells with the same electron structure as the nearest Nobel gas

33
Q

what is a dative/coordinate covalent bond?

A

when both electrons come from the same atom

-the shared electron pair was originally a lone pair of electrons on one of the bonded atoms

34
Q

what is the direction of the covalent bond?

A
  • the attraction is localised acting solely between the shared pair of electrons and the nuclei of the two bonded atoms
  • it is a directional force
35
Q

what are multiple covenant bonds?

A

they exist when two atoms share more than one pair of electrons
double/triple covenant bonds is when there are two/three shared pairs of electrons between the nuclei of the bonding atoms

36
Q

why do simple molecular have low melting and boiling points, whilst giant have high?

A
  • due to weak intermolecular forces between molecules which require little energy to break apart
  • yet in giant there are strong covalent bonds between atoms which require lots of energy to break apart
37
Q

why don’t covenant substances conduct electricity?

A
  • there are no free electrons to act as mobile charge carriers as they tend to be used in covalent bonds
  • even in cases where electrons may be delocalised within a molecule there isn’t sufficient contact between the molecules to allow electrons to move through the whole solid or liquid
38
Q

what is electron pair repulsion theory?

A
  • the shape of a molecule is determined by the number of electron pairs surrounding the central atom
  • as all electron pairs are negatively charged they repel one another until they’re as far apart as possible
  • this holds the bonds in a definite shape
39
Q

what did the different lines represent in terms of bonds?

A
  • a solid line is a bond in the plane of the paper
  • a solid wedge comes out of the plane of the paper
  • a dotted wedge goes into the plane of the paper
40
Q

what is significant about lone pairs in electron repulsion theory?

A

lone pairs sit slightly closer to the central atom and occupy more space than a bonded pair

  • this means they repel more strongly slightly narrowing the bond angle
  • for each lone pair the bond angle is reduced by 2.5 degrees
41
Q

what is the linear shape?

A

2 electron pairs

-180 degree bond angles

42
Q

what is the bent shape?

A

2 lone pairs and two bonding pairs

-bond angles of 104.5 degrees

43
Q

what is the tetrahedral shape?

A
  • 4 electron pairs

- 109.5 degree bond angles

44
Q

what is the pyramidal shape?

A
  • one lone pair and 3 bonding pairs

- bond angles of 107 degree

45
Q

what is the trigonal planar shape?

A
  • three bonded pairs

- 120 degree bond angles

46
Q

what is the trigonal bipyramidal shape?

A
  • 5 bonded pairs
  • 90 degree bond angles for two
  • 120 degree bond angles for three
47
Q

what is the octahedral shape?

A

6 bonded pairs of electrons

-90 degree bond angles

48
Q

what is the shape of the ammonium and sulphate ion?

A
  • ammonium 4 bonding pairs around the central atom creating a tetrahedral shape
  • sulphate has four regions of electron density
49
Q

what is the shape of the carbonate and nitrate ion?

A
  • they have three regions of electron density around the central atom
  • this forms a trigonal planar shape
50
Q

what is electronegativity?

A

the ability of an atom to attract the bonding electrons in a covenant bond

  • this is shown on the Pauling scale, the more electronegative the atom the higher the number
  • across the periodic table, the nuclear charge increases and the atomic radius decreases
51
Q

how can electronegativity affect polarity?

A
  • if the molecule is symmetrical the atoms will have the same electronegativity so electrons will be evenly spaced
  • yet if the atoms have different electronegativities it means the electrons won’t be shared evenly forming a polar bond
52
Q

how can polar bonds form non-polar molecules?

A

polar bonds occur when bonded atoms have different electronegativity values meaning electrons are unevenly distributed
-yet if the molecule is symmetrical they cancel forming a non polar molecule

53
Q

what are inter and intra molecular forces?

A
  • inter is between molecules

- intra is within molecules

54
Q

what is the scale in strength of intermolecular forces?

A

hydrogen bonding is strongest then permanent then induced

50-10-1 times the strength

55
Q

how do induced dipole dipole interactions work?

A
  • movement of mobile electrons produces a changing dipole in a molecule
  • at any instant, an instantaneous dipole will exist but its position is constantly shifting
  • the instantaneous dipole induces a dipole on a neighbouring molecule
  • the induced dipole induces further dipoles on neighbouring molecules which then attract one another
  • these are only temporary and can disappear quickly
56
Q

what are London dispersion forces?

A

weak intermolecular forces that exist between all molecules whether polar or non-polar
-they act between induced dipoles in different molecules

57
Q

why can induced dipole dipole interactions work?

A
  • in symmetrical molecules electrons aren’t static meaning they can be nearer one atom rather than another at anytime
  • these oscillations create the instantaneous dipoles
58
Q

what are permanent dipole-dipole interactions?

A
  • weak attractive force that acts between the permanent dipoles in different polar molecules
  • polar molecules have permeant dipoles
59
Q

what is hydrogen bonding?

A

a type of intermolecular force which arises when:

  • an electronegative element is attached to a hydrogen atom (H,N,F)
  • the hydrogen forms an interaction with a lone pair of electrons on an electronegative atom
60
Q

based off hydrogen bonding why is ice less dense than water?

A
  • two lone pairs on the oxygen atom and two hydrogen atoms, each water molecule can form four hydrogen bonds
  • these extend outwards holding water molecules slightly apart and forming an open tetrahedral lattice full of holes (bond angles around each hydrogen atom is close to 180)
  • when it melts the structure collapses removing these holes meaning molecules move closer together forming a denser liquid
61
Q

based off hydrogen bonding, why does water have a relatively high melting and boiling point?

A

as with all molecules water has London forces between molecules

  • therefore hydrogen bonds are extra forces over and above the London forces
  • a large amount of energy is needed to overcome these forces
62
Q

based off hydrogen boning, why does water have high surface tension and viscosity?

A

hydrogen bonds means water molecules are relatively strongly attached to each other so water flows less easily than expected increasing viscosity
-strong properties can allow small objects/ insects to walk on surface

63
Q

what determines the strength of induced dipole-dipole interactions?

A
  • the more electrons in each molecule, the larger the instantaneous dipole, so the greater the induced dipole-dipole interactions increasing the attractive forces
  • also the more electronegative element the greater the induced dipole
64
Q

how do you predict the solubility of non polar substances ?

A

when a simple molecular compound is added to a non polar solvent intermolecular forces form between them

  • these interactions weaken the intermolecular forces in the lattice allowing the compound to dissolve
  • therefore non polar simple molecular substances tend to be soluble in non-polar solvents
  • when a simple molecular compound is added to a polar solvent there is little interaction between molecules so the intermolecular bonding is often too strong to break so they tend to be insoluble in polar solvents
  • some contain both polar and non polar parts of their structure so can dissolve in both polar and non-polar solvents
65
Q

why is chlorine a gas but iodine a solid?

A

more electrons in iodine molecules

-this creates stronger dipoles in the molecule and therefore stronger induced dipole dipole interactions

66
Q

orbital

A

a region within an atom that can hold up to two electrons (with opposite spin)

67
Q

what causes stronger ionic bonds?

A
  • compounds with a greater ionic charge as there is greater attraction between ions
  • more energy required to break these bonds
68
Q

isoelectronic

A

having the same number of electrons/ electronic structure

69
Q

how do ionic compounds dissolve

A
  • delta positive hydrogen attracts negative ions in ionic compound
  • delta negative oxygen attracts positive ions in ionic compound
  • pulls compound apart and it dissociates

A Level Chemistry (21 decks)

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