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A-Level Chemistry > Structure and Bonding > Flashcards

Structure and Bonding Flashcards

1
Q

Ionic Bonding

A
  • An electrostatic attraction between 2 oppositely charged ions
  • Happens between metals and non-metals
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2
Q

Properties of Ionic Compounds

A
  • Always solid at room temperature
  • Conduct electricity when molten or dissolved as ions are free to move and carry charge
  • High melting and pointing points as lots of energy is needed to break strong electrostatic forces of attraction between the ions
  • Brittle and shatter easily when the layers of alternating charge are distorted in a lattice. The charges repel causing the lattice to fragment
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3
Q

Covalent Bonding

A
  • Electrostatic attraction between the nucleus of an atom and a shared pair of electrons
  • Happens between non-metals
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4
Q

Double Bond

A
  • When the atoms each share 2 electrons with each other
  • E.g. Carbon Dioxide
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5
Q

Triple Bond

A
  • When the atoms each share 3 electrons with each other
  • E.g. Carbon Monoxide
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6
Q

Properties of Simple Molecular Compounds

A
  • Low melting and boiling points due to weak Van Der Waals forces
  • Don’t conduct electricity because there are no particles that can carry charge
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7
Q

Dative Covalent Bond/Coordinate Bond

A
  • A bond where both electrons in the shared paired are supplied by the same atom
  • Represented using an arrow
  • Once a dative bond has formed, it is treated as a standard covalent bond as it reacts in the same way as one
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8
Q

Examples of Dative Covalent Bonds

A
  • NH3 and H+ become NH4+
  • A double bond between carbon and oxygen becomes a triple bond (oxygen shares an extra lone pair so carbon also has a full outer shell)
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9
Q

Metallic Bonding

A
  • A lattice of positively charged ions surrounded by a sea of delocalised electrons
  • Strong electrostatic forces of attraction between the oppositely charged ions
  • Occurs between metals
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10
Q

Properties of Metallic Structures

A
  • Good conductors of electricity/heat
  • Malleable
  • Ductile
  • High melting and boiling points
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11
Q

Explanation of Metallic Structure Properties

A
  • Good conductors of electricity/heat as they have delocalised electrons that can carry charge through the structure
  • Malleable and ductile as the layers of positive ions are able to slide over one another
  • High melting/boiling points due to strong electrostatic forces of attraction which require lots of energy to break
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12
Q

Electronegativity

A
  • The tendency of an atom to attract a bonding pair of electrons in a covalent bond
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13
Q

Factors impacting Electronegativity

A
  • Atomic Radius
  • Distance from nucleus
  • Nuclear Charge
  • Electron Shielding
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14
Q

How does Atomic Radius impact Electronegativity?

A

A smaller atom has a higher electronegativity as the pair of electrons is closer do the nucleus so there is less shielding

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15
Q

How does Nuclear Charge impact Electronegativity?

A

Increased nuclear charge increases electronegativity as the more protons there are, the stronger the attraction to the shared pair of electrons

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16
Q

What is the trend in electronegativity along a period and why?

A
  • Electronegativity increases because the nuclear charge increases but the shielding stays the same
  • There is a greater attraction to the shared pair of electrons so there is a higher electronegativity
17
Q

What is the trend in electronegativity down a group and why?

A
  • Electronegativity decreases but shielding increases
  • Shared pairs of electrons are less attracted to the nucleus so electronegativity decreases
18
Q

How does a bond become polar?

A

When there is a clear difference in electronegativity of the atoms involved in a covalent bond

19
Q

What 2 things does a molecule need to be a polar molecule

A
  • Contain polar bonds
  • Not be symmetrical in terms of polar bonds
20
Q

What causes symmetry in molecules?

A
  • When the bonds are all the same (e.g. AlCl3)
  • In symmetrical molecules, the polar bonds cancel each other out
21
Q

What type of molecule has intermolecular forces?

A

Covalent compounds with a single molecular structure

22
Q

Types of Intermolecular Forces

A
  • Permanent dipole forces
  • Hydrogen Bonding
  • Induced dipole-dipole forces (AKA Van Der Waals forces)
  • Ion induced dipole forces
23
Q

Van Der Waals Forces

A
  • Weakest type of intermolecular force
  • All simple covalent molecules have Van Der Waals forces
  • All atoms and molecules have positive and negative charges even though they are neutral overall
  • These charges produce very weak electrostatic forces of attraction between all atoms and molecules
24
Q

Permanent Dipole Forces

A
  • Occurs between polar molecules when there is a difference in electronegativity between atoms
  • The more electronegative atom will attract the bonding pair of electrons and this creates an electronegative region and an electropositive region
  • The electronegative region of one atom will be attracted to the electropositive region of another atom
  • This creates a lattice structure as many molecules are held together
25
Q

Linear

A
  • 2 bonding pairs
  • 0 lone pairs
  • Bond angle: 180 degrees
26
Q

Trigonal Planar

A
  • 3 bonding pairs
  • 0 lone pairs
  • Bond Angle: 120
27
Q

Tetrahedral

A
  • 4 bonding pairs
  • 0 lone pairs
  • Bond Angle: 109.5
28
Q

Trigonal Pyramidal

A
  • 4 bonding pairs
  • 1 lone pair
  • Bond Angle: 107
29
Q

Bent

A
  • 4 bonding pairs
  • 2 lone pairs
  • Bond Angle: 104.5
30
Q

Trigonal Bipyramidal

A
  • 5 bonding pairs
  • 0 lone pairs
  • Bond Angles: 120 and 90
31
Q

Seesaw

A
  • 5 bonding pairs
  • 1 lone pair
  • Bond Angles: 102 and 86.5
32
Q

T-Shape

A
  • 5 bonding pairs
  • 2 lone pairs
  • Bond Angle: 87.5
33
Q

Linear (5 pairs)

A
  • 5 bonding

A-Level Chemistry (12 decks)

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