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A Level - Chemistry > 3.1.3 Bonding > Flashcards

3.1.3 Bonding Flashcards

1
Q

Ionic Bonding: definition

A

strong electrostatic forces of attraction between oppositely charged ions formed by electron transfer in all directions

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2
Q

Ionic Bonding: structure?

A

giant ionic lattice

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3
Q

Ionic Bonding: mp/bp?

A

HIGH:
lots of energy required to overcome strong electrostatic forces of attraction between oppositely charged ions in giant lattice structure
-> influenced by charge density

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4
Q

how does charge density affect the mp/bp of ionic bonds?

A

-charge of the ion:
higher the charge, higher mp/bp

-ionic radius:
smaller the radius, higher mp/bp

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5
Q

Ionic Bonding: conductivity

A

-conducts as liquid or aqueous solutions as ions are free to move and carry a charge through the structure
-doesn’t conduct when solid

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6
Q

Simple Molecular Covalent Bonding: definition

A

a shared pair of electrons between atoms

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7
Q

Simple Molecular Covalent Bonding: structure?

A

simple molecular

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8
Q

Simple Molecular Covalent Bonding: mp/bp?

A

LOW:
little energy needed to overcome weak (van der waals) forces of attraction between molecules

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9
Q

difference between the van der waals forces and the covalent bonds in simple molecular covalent bonding?

A

-strong covalent bonds between atoms

-weak van der waals forces of attraction between molecules

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10
Q

are there any lone electrons in simple covalent bonding?

A

No ❤️

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11
Q

Simple Molecular Covalent Bonding: conductivity?

A

-not conductive as no mobile charged particles to carry a charge through the structure

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12
Q

do covalent bonds break during state change?

A

No ❤️

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13
Q

Macromolecular Covalent Bonding: definition?

A

lattice of many atoms held together by strong covalent bonds

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14
Q

Macromolecular Covalent Bonding: structure?

A

giant covalent lattice

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15
Q

Macromolecular Covalent Bonding: mp/bp?

A

HIGH:
requires lots of energy to overcome many strong covalent bonds

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16
Q

Macromolecular Covalent Bonding: conductivity?

A

diamond & sand: POOR - electrons can’t move

graphite: GOOD - free delocalised electrons between layers

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17
Q

Graphite: structure?

A

giant covalent lattice

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18
Q

Graphite: definition?

A

-layers of carbon atoms (each C atom bonded to 3 others)
-held together by weak van der waals forces of attraction
-which allows them to slide over eachother

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19
Q

Graphite: conductivity?

A

YES:
one electron from each carbon is delocalised and can carry a charge through the structure

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20
Q

Graphite: mp/bp?

A

HIGH:
strong covalent bonds which require lots of energy to overcome

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21
Q

Graphite: properties?

A

-soft & slippery
-good for pencils, lubricants & electrodes

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22
Q

Diamond: structure?

A

giant covalent lattice

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23
Q

Diamond: definition?

A

-3d network of strong covalent bonds (each C atom bonded to 4 others)
-NOT HELD together by weak van der waals forces of attraction
-therefore they CANT slide over eachother

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24
Q

Diamond: conductivity?

A

NO:
no free electrons / ions

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25
**Diamond**: mp/bp?
strong covalent bonds which require lots of energy to overcome
26
**Diamond**: properties?
-extremely hard - due to strong covalent bonds -used in cutting tools / jewellery due to strength & brilliance
27
**Metallic Bonding**: definition?
electrostatic force of attraction between the metal positive ions and the delocalised electrons
28
**Metallic Bonding**: structure?
giant metallic lattice
29
**Metallic Bonding**: mp/bp?
**HIGH**: strong electrostatic forces between positive ions and sea of delocalised electrons
30
**Metallic Bonding**: conductivity
**YES**: delocalised electrons can move through structure and carry a charge
31
**Metallic Bonding**: properties?
-malleable as positive ions in the lattice are all identical so ions can slide over eachother -attractive forces in the lattice are the same whichever ions are adjacent
32
how does the strength of **Metallic Bonds** change across the periodic table?
**INCREASES**: -higher melting & boiling points, stronger higher charge on metal ions -more delocalised electrons per ion -stronger force of attraction between them
33
**Electronegativity**: definition?
the power of an atom to attract the electron density in a covalent bond towards itself
34
what 3 factors affect **Electronegativity**?
-**Shielding** -**Nuclear Charge** -**Atomic Radius**
35
how does *shielding* affect **electronegativity**?
-as shielding **increases**, electronegativity **decreases** -more energy levels = more repulsion -weaker attraction between nucleus + bonding electrons
36
how does *nuclear charge* affect **electronegativity**?
-as nuclear charge **increases**, electronegativity **increases** -more protons = larger nuclear charge -stronger attraction between nucleus and bonding electrons
37
how does *atomic radius* affect **electronegativity**?
-as atomic radius **increases**, electronegativity **decreases** -bonding electron further from nucleus -weaker attraction between bonding electrons + nucleus
38
what is the most electronegative element?
fluorine - largest nuclear charge for its electron shielding, small atomic radius -> **Pauling Scale**: 4.0
39
**Electronegativity**: across a period?
electronegativity **increases** ->increased nuclear charge ->decreased atomic radius
40
**Electronegativity**: down a group?
-electronegativity **decreases** ->increased atomic radius ->increased shielding NOTE: although there is also an increase in nuclear charge, which should in theory increase electronegativity, this is offset by the increased atomic radius & shielding
41
**Polarity**: definition?
the unequal sharing of electrons in a covalent bond (different electronegativities)
42
**Non-Polarity**: definition?
equal sharing of electrons in a covalent bond (same electronegativities)
43
why is C-H an exception?
although carbon (2.5) and hydrogen (2.1) have different electronegativities it isn’t a large enough difference so is still considered **non-polar**
44
(lower electronegativity) partially positive symbol?
𝛿+
45
(higher electronegativity) partially negative symbol?
𝛿−
46
common **Polar Bonds**?
C—Cl C—O O—H N—H F—H Cl—H C==O or if it includes: Cl, O, N or F
47
why can molecules still be **non-polar** overall even if they have **polar** bonds?
-they are linear -the molecule is symmetrical and the electron density is being pulled in equal + opposite directions e.g O𝛿− ==C𝛿+ == O𝛿−
48
what is the rule of thumb when it comes to determining whether **polar** or **non-polar**?
-**Lone Pair**: if there is a lone pair it is most likely to be polar -> distorts other bonds -**Different Elements**: if there are different elements bonded to the central atom it is most likely polar
49
exceptions to the lone pair rule of thumb?
XeF4 CF4 SF6 Cl2Cl4 NF3 PF3 BF3 SeF6 CCl4
50
what are the 3 types of **Intermolecular Forces**?
1. **Van der Waals** 2. **Dipole - Dipole** 3. **Hydrogen Bonding**
51
**Van der Waals**: other names?
-London Forces -Tempory Dipole Induced Dipole
52
**Van der Waals**: definition?
-at any given time, the electrons could be distributed in an uneven way (electron density can fluctuate) and form a temporary dipole -these temporary dipoles can cause other temporary dipoles to form in neighbouring molecules forming induced dipoles -these are always the opposite sign to the original one
53
what do van der waals forces occur between?
-all **molecular** substances & noble gases -NOT **ionic** substances -if it has **electrons** is has van der waals
54
are van der waals forces stronger in smaller or larger molecules?
**Larger** - more electrons
55
what is the weakest type of inter-molecular force?
Van Der Waals forces
56
**Dipole - Dipole**: definition?
-permanent dipole-dipole forces have permanently dipole -only occurs between polar molecules -asymmetrical and have a bond where there is a significant difference in electronegativity between the atoms
57
**Hydrogen Bonding**: definition?
-like dipole-dipole on steroids -when a hydrogen atom is bonded to one of the 3 most electronegative atoms of: ->**nitrogen** ->**oxygen** ->**fluorine** -which must have an available lone pair of electrons
58
what is the strongest type of inter-molecular force?
hydrogen bonding
59
in hydrogen bonding which partial charges do the O/F/N w lone pairs and H atoms have?
lone pairs: 𝛿− H atoms: 𝛿+
60
how to determine **Molecular Shape**?
1. **work out total electron pairs**: group no. of central atom + no. if other atoms / 2 = total electron pairs 2. **bond pairs** = total no. of atoms surrounding central 3. **lone pairs** = total electron pairs - bond pairs
61
how to determine **Molecular Ion** shape?
in step 1 of previous calculation: -> if ion is **+** subtract **1** electron -> if ion is **-** add **1** electron (done to numerator)
62
**Dative/Co-ordinate Covalent Bond**: definition?
formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion with a lone lake of electrons
63
**Valence Shell Electron Pair Repulsion**: definition?
in a molecule, electrons will position themselves as far apart from eachother as possible, to minimise repulsion -> lone pairs repel more than bond pairs
64
molecules rule of thumb?
-group 3 central atoms usually have incomplete outer shells -group 4 central atoms tend not to form co-ordinate bonds -group 5,6,7 have 1,2,3 lone pairs respectively so can be lone pair donars
65
how do **lone pairs** repel more than **bond pairs**?
-a molecule w one or more lone pairs will push bonding pairs closer together -more lone pairs, the closer these bonding pairs are pushed together
66
**Dative/Co-ordinate Covalent Bond**: criteria?
**1st atom**: a lone pair **2nd atom**: any particle (atom or ion) with an incomplete shell of electrons
67
**Strength of Intermolecular Forces**: Van der Vaals
-larger molecules (mr) have greater VdW forces -because they have more electrons, so will form larger dipoles (with greater 𝛿− and 𝛿+)
68
**Strength of Intermolecular Forces**: Dipole-Dipole
-dipole-dipole forces in molecules that are of similar sizes have stronger intermolecular forces and higher melting / boiling points
69
**Strength of Intermolecular Forces**: Hydrogen Bonds
-strongest IMF, so will lead to the highest melting/boiling point

A Level - Chemistry (7 decks)

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