Chemical Bonding Flashcards

1
Q

Valency and ionisation energy rule

A

In order to remove electrons that are closer to the nucleus than the valence electrons, a lot more energy is needed, so if there is a big jump in IE in between the 3rd and 4th for example, it means the element has 3 valence electrons and is in group 3

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2
Q

Types of chemical bonding (3)

A

Ionic
Metallic
Covalent (pure and polar)

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3
Q

Electronegativity

A

The power of an atom to attract electrons to itself

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4
Q

Pure covalent bond electronegativity value

A

0 - 0.4

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5
Q

Polar covalent bond electronegativity value

A

0.5-1.9

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6
Q

Ionic bond electronegativity value

A

> 1.9

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7
Q

Factors that affect electronegativity (2)

A

Across the period
Down the group

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8
Q

How moving across the group affects electronegativity

A

As you move across the period, there in an increase in the number of protons which results in a greater nuclear charge and a larger electronegativity value

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9
Q

How moving down the group affects electronegativity

A

As we move down the group, the atomic radius increases along with the shielding effect resulting in a lower electronegativity value

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10
Q

Ionic bonding

A

The electrostatic attraction between oppositely charges ions (positively charged cations and negatively charged anions

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11
Q

Ionic bond properties (4)

A

High MP+BP - strong electrostatic forces between oppositely charged ions
Conducts if molten/aqueous - If solid the ions are in a fixed crystal lattice = can’t carry charge
Brittle
Soluble in polar solvents

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12
Q

Metallic bonding

A

Electrostatic attraction between positive cations and delocalised electrons

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13
Q

Properties of metallic bonds (3)

A

Malleable and ductile (due to non-directional bonds)
High conductivity (due to delocalised electrons)
High melting and boiling point(strong electrostatic force between cations and anions(the high the P number the more))

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14
Q

Covalent bonding

A

The electrostatic attraction between the nuclei of 2 atoms and shared pair of electrons

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15
Q

Polar covalent

A

When there is an unequal distribution of charge

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16
Q

Single bond (3)

A

(Single sigma (σ) bond)
Overlap of s-orbitals
Overlap of s and p-orbitals
Head to toe overlap of p-orbitals

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17
Q

Pi bond

A

Forms from the sideways overlap of p-orbitals

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18
Q

Double bond

A

1 σ (sigma) bond and 1 π (pi) bond
CAN ONLY FORM IF YOU HAVE A P VALENCE ELECTRON

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19
Q

Dative covalent bond

A

(Coordinate bond)
When a substance shares its lone pair of electrons with another substance, only occurs when an atom has an incomplete octet

20
Q

Molecular shapes

A

Based on valence shell electron pair repulsion theory (VSEPR), electrons pairs need to be as far from each other as possible
Based on :
-no. of areas of negative charge
-lone pairs

21
Q

Ions rule

A

Gained/lost by the central atom only

22
Q

Pure covalent bond

A

No unequal distribution of charge

23
Q

Dipole moment

A

Unequal distribution of charge

24
Q

What determines if a molecule is polar (2)

A

Whether bond is polar or not
Molecule shape (symmetrical :i ndividual dipoles cancel each other out)

25
Q

Polar and non-polar solubility rule

A

Like dissolves like

26
Q

IMF vs bonds

A

IMF is between molecules, bonds is within molecules

27
Q

Van Der Waals forces (3)

A

Hydrogen bonding
Pd-pd
Id -id

28
Q

Hydrogen bonding

A

Strongest VDW force, when H is directly bonded to N O F

Hydrogen bonding is a special case of permanent dipole - permanent dipole force between molecules where hydrogen is bonded to a highly electronegative atom

29
Q

Pd-pd

A

Permanent dipole-permanent dipole
2nd strongest VDW that occurs between polar molecules
Carbon to N, O, halogens,
Hydrogen to Cl and Br

30
Q

Id-id

A

Instantaneous dipole - induced dipole/ London dispersion
Non-polar molecules
Weakest VDW, thenmore electrons the stronger

31
Q

Anomalous properties of water (3)

A

Due to high no of hydrogen bonds:
-relatively high MP+BP
-relatively high surface tension
Low density of the solid ice compared with water

32
Q

Surface tension

A

The tendency of molecules of a liquid to be attracted more towards one another at the surface of the liquid than to the air above it

33
Q

Buckminsterfullerene

A

C60, buckyballs
Carbon molecule made up of 60 atoms arranged like the faces of a soccer ball (pentagon and hexagons). Simplest of a family of similar nanoparticles known as fullerenes

34
Q

Covalent radius of a carbon atom

A

0,077 nm

35
Q

Nanoparticles

A

Usually have sizes in the range of 1-100nm (1nm is 10-9 metres)

36
Q

Properties/characteristics of buckminsterfullerene (4)

A

Due to van der Waals dispersion IMF forces, it has a lower Mp than diamond/graphite
Sublimes at 800k (527*C) vs Diamond and graphite at 4000K
Insoluble in water but slightly soluble in organic solvents (benzene/methylbenzene)
More slippery than Teflon (PTFE -poly(tetrafluoroethene))

37
Q

Solubility of C60

A

(Buckminsterfullerene)
Insoluble in water since it can’t for hydrogen bonds with it
Slightly soluble in organic solvents eg. Benzene since it forms van der Waals attractions with them

38
Q

Carbon nanotube

A

Single sheet of carbon atoms which make up graphite (graphene) rolled up

39
Q

Characteristics of nanotubes (5)

A

-Have a diameter of about 1nm, can be very long. Individual tubes are very strong and stiff due to strong covalent bonds between atoms making up the tubes
-Van Der Waals forces between individual tubes is weak so bulk material isn’t so strong
-May be open ended or capped one side/both by half a Bucky ball
-Delocalised electron suggests they should be good conductors of electricity (can achieve by changing the way they are made)
-Delocalised electrons also shows that they are good conductors of heat (transferred via electron movement. Conductivity is good along the tube, not across.

40
Q

Structure of graphene

A

Single sheet from a graphite structure, 2D
Extends indefinitely in both dimensions
Stacking them would give you graphite

41
Q

Giant metallic bond properties(3)

A

Malleable/ductile due to non-directional bonds
High MP+BP due to strong electrostatic forces
Good conductor of electricity due to delocalised electrons

42
Q

Giant ionic bonds

A
43
Q

Giant ionic bond properties (3)

A

Brittle
Conducts electricity when molten/aqueous
High MP+BP due to strong electrostatic forces

44
Q

Giant covalent bond properties (

A
45
Q

Giant covalent bond properties (

A