Topic 4/14: Bonding Flashcards

1
Q

Define volatility.

A

The tendency of a substance to vaporize

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2
Q

Define ionic bond.

A
  • Electrostatic attraction between oppositely charged ions
  • Only occurs between metals (positive charge) and non-metals (negative charge)
  • Forms a neutral lattice
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3
Q

Outline physical properties of ionic compounds

A
  • Low volatility (low tendency to vaporize)
  • High melting temperatures
  • Conduct electricity in molten state (freely moving ions)
  • Soluble in polar substances
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4
Q

Define covalent bond.

A
  • Electrostatic attraction between a shared pair of electrons and the positively charged nucleus
  • Generally occur between non-metals
  • Atoms with similar EN are likely to form a covalent bond (same affinity for electrons, no tendency to donate electrons)
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5
Q

Outline the strengths of electron repulsion.

A

Lone pair - lone pair > lone pair - bonding pair > bonding pair - bonding pair

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6
Q

Describe properties of diamond.

A
  • Each carbon atom is joined to four other carbon atoms ➜ Giant covalent structure
  • Tetrahedral structure held by strong covalent bonds
  • High MP
  • No delocalized electrons ➜ Low conductivity
  • 109 angle
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7
Q

Describe properties of C60 fullerene.

A
  • Sphere made of atoms arranged in a hexagon
  • Covalent bonding and London dispersion forces
  • Each carbon atom attached to three others
  • Delocalized electrons ➜ Good conductivity
  • 109~120 angles
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8
Q

Define sigma bonds.

A

Formed by the head-on overlap of orbitals

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9
Q

Define pi bonds.

A

Formed by the sideway overlap of adjacent p-orbitals

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10
Q

Formal charge equation

A

FC = V - (1/2B + L)

  • V=Valence electron
  • B=bonding electrons
  • L=lone pair electrons
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11
Q

Define hybridization.

A
  • A hybrid orbital results because of the mixing of different types of atomic orbitals on the same atom
  • Four electron domains: sp3
  • Three electron domains: sp2
  • Two electron domains: sp
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12
Q

Outline characteristics of a polar molecule.

A
  • Asymmetrical
  • Polarities of polar bonds cannot cancel each other
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13
Q

Outline characteristics of non-polar molecules.

A
  • Symmetrical
  • Polarities of polar bonds can cancel each other
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14
Q

Define metallic bonding.

A

Electrostatic attraction between a lattice of positive ions and the delocalized sea of electrons

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15
Q

Outline the characteristics of metals.

A
  • Malleable (layers of metals can slide over each other without breaking bonds)
  • Ductile
  • Good conductors of heat and electricity (delocalized electrons)
  • Low EN values: lose electrons easily to form positive ions
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16
Q

Describe characteristics of alloys.

A
  • Contain more than one metal
  • Stronger due to disturbance of the regular network of positive ions
  • Atoms of different sizes ➜ Difficult for layers of positive ions to slide over each other
17
Q

Define cations.

A

Atoms that lose electrons and have a positive net charge (Positive ions)

18
Q

Define anions.

A

Atoms that gain electrons and therefore have a negative net charge (negative ions)

19
Q

Define bond length.

A
  • Distance between two bonded nuclei
  • Decreases as the number of electron pairs increases because there is a greater attractive force between the two nuclei
20
Q

Define bond strength.

A
  • The energy required to break the bond, described in terms of bond enthalpy
  • Increases as the number of electron pairs increases, as more energy is required to break them
21
Q

Define covalent compounds.

A

Formed when two or more non-metal atoms bond by sharing valence electrons

22
Q

Define octet rule.

A

The tendency of atoms to gain a valence shell with a total of 8 electrons

23
Q

Which atom is the central atom in a Lewis structure?

A

The atom with the lowest EN, furthest away from fluorine

24
Q

Which atoms are exceptions to the octet rule?

A
  • Boron
  • Beryllium
  • Elements in period 3 and below may expand octets by using d-orbitals in their valence shell
25
Q

Name molecules with 2 electron domains.

A

2 BP, 0 LP ➜ Linear, 180 angle

26
Q

Name molecules with 3 electron domains.

A
  • 3 BP, 0 LP ➜ Trigonal planar, 120 angle
  • 2 BP, 1 LP ➜ Bent, 117 angle
27
Q

Name molecules with 4 electron domains.

A
  • 4 BP, 0 LP ➜ Tetrahedral, 109.5 angle
  • 3 BP, 1 LP ➜ Trigonal pyramidal, 107 angle
  • 2 BP, 2 LP ➜ Bent, 104.5 angle
28
Q

Name molecules with 5 electron domains.

A
  • 5 BP, 0 LP ➜ Trigonal bipyramidal, 90 and 120 angles
  • 4 BP, 1 LP ➜ See-saw, 90 and 117 angles
  • 3 BP, 2 LP ➜ T-shaped, 90 angle
29
Q

Name molecules with 6 electron domains.

A
  • 6 BP, 0 LP ➜ Octahedral, 90 angle
  • 5 BP, 1 LP ➜ Square pyramidal, 90 angle
  • 4 BP, 2 LP ➜ Square planar, 90 angle
30
Q

Describe simple covalent structures.

A
  • A few atoms held by strong covalent bonds
  • Weak intermolecular forces ➜ Low BP, liquid or gaseous state
  • No free electrons/overall charge ➜ non-conductive
31
Q

Describe giant covalent structures.

A
  • Contain a lot of non-metal atoms joined by covalent bonds
  • Arranged into giant regular lattices
  • Involves many bonds ➜ Strong structures
  • Strong covalent bonds ➜ High MP
32
Q

Describe properties of graphite.

A
  • Hexagonal layer structure
  • Strong covalent bonds between carbon atoms in each layer
  • Weak Van Der Waals forces between the layers ➜ Layers slide over easily
  • Delocalized electrons between layers ➜ Good conductivity
  • 120 angle
33
Q

What is the difference between intermolecular forces and intramolecular forces?

A
  • Intermolecular: forces between molecules
  • Intramolecular: force between atoms (ionic and covalent)
34
Q

Describe the three intermolecular forces.

A

London Dispersion

  • Weakest
  • Temporary dipoles

Dipole-Dipole

  • Dipole: molecule with both positive and negative regions
  • Positive side of a polar molecule attracts negative side of another polar molecule
  • Strength depends on distance and orientation

Hydrogen bonds

  • Strongest
  • Attraction between partial positive hydrogen on one molecule and partial negative atom on another molecule
  • NOF: nitrogen, oxygen, fluorine
35
Q

Describe properties of metals.

A
  • Good conductors of heat and electricity
  • Highest conductivity when aqueous or melted
  • Malleable
  • Ductile
  • Low EN ➜ lose electrons easily to form positive ions