1.8 & 1.9 : Covelant Bonding Flashcards by Zohaib Hussain

What 5 factors favour covelant bonding?

High ionization energies
Equal electron affinities
Equal/similar electronegativity
High nuclear charge
Small atomic size

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Define “lone pair of electrons”

A pair of electrons in the valence shell of the atom
that are not involved in bonding

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What is a dative (co-ordinate) covelant bond?

Bond where both shared electrons come from one atom/ion.

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What are the conditions for dative covelat bond formation?

Donating atom must have a lone pair of
electrons
Accepting atom should have a vacant
orbital to accept the electron pair donated by the donor

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Learn slide 19

Dative bonding in biology

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The unction of some drugs depends on their ability to:

*act as donors in dative covalent bonds – chelation therapy
* act as acceptors for biological donors

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Learn Slide 20 examples

Drugs

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Which Theory is used to predict the structure of simple covelantly bonded molecules and ions?

Valence Shell Electron Pair Repulsion theory
(VSEPR)

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What is the characteristic of the 3D shape of a simple molecule/ ion?

Keep repulsive forces to a minimum - electron pairs stay as far apart as possible

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What do we use to predict the shape of a molecule?

Number of electron pairs

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Describe a molecule with 2 bond pairs

• Linear shaped
• 180° bond angles

Example: BeCl2

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Describe a molecule with 3 bond pairs

• Trigonal planar shape
• 120° bond angles

Examples: AlCl3

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Describe a molecule with 4 bond pairs

• Tetrahedral shaped
• 109.5° bond angles

Example: CH4

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Describe a molecule with 5 bond pairs

• Trigonal Bipyramidal shape
• 90° AND 120° bond angles

Example: PCl5

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Describe a molecule with 6 bond pairs

• Octahedral shape
• 90° bond angles

Example: SF6

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Describe molecule with:
2 bond pairs
1 lone pair

• 3 electron domains
• Domain geometry = trigonal planar
• Molecule geometry = Bent linear

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Describe molecule with:
1 bond pair
2 lone pairs

• 3 electron domains
• Domain geometry: Trigonal planar
• Molecule geometry: Linear

Describe molecule with:
3 bond pairs
1 lone pair

• 4 electron domains
• Domain geometry: Tetrahedral
• Molecular geometry: Pyramidal

Describe molecule with:
2 bond pairs
2 lone pairs

4 electron domains
Domain geometry: Tetrahedral
Molecular geometry: Bent linear

Describe molecule with:
1 bond pair
3 lone pairs

4 electron domains
Domain geometry: Tetrahedral
Molecular geometry: Linear

How many degrees does each lone pair decrease bond angles?

2 degrees

Describe molecule with:
4 bond pairs
1 lone pair

5 electron domains
Domain geometry: Trigonal bipyramid
Molecular geometry: Seesaw

Describe molecule with:
3 bond pairs
2 lone pairs

5 electron domains
Domain geometry: Trigonal bipyramid
Molecular geometry: T-shaped

Describe molecule with:
2 bond pairs
3 lone pairs

5 electron domains
Domain geometry: Trigonal bipyramid
Molecular geometry: Linear

Describe molecule with: 5 bond pairs 1 lone pairs

* 6 electron domains * Domain geometry: Octahedral * Molecular geometry: Square pyramidal

Describe molecule with: 4 bond pairs 2 lone pairs

* 6 electron domains * Domain geometry: Octahedral * Molecular geometry: Square planar

Describe molecule with: 3 bond pairs 3 lone pairs

* 6 electron domains * Domain geometry: Octahedral * Molecular geometry: T-shaped (theoretical)

Describe molecule with: 2 bond pairs 4 lone pairs

* 6 electron domains * Domain geometry: Octahedral * Molecular geometry: linear

What bond angle do linear molecules still have?

180 degrees

What does no difference in electronegativity between two atoms lead to? Example?

Pure non-polar covelant bonds Cl-Cl

What does a small difference in electronegativity between two atoms lead to? Example?

Polar covelant bonds C-Cl

What do polar bonds affect?

Reactivity of the bond and types of intramolecular forces between molecules

What does a large difference in electronegativity between two atoms lead to? Example?

Ionic bonds NaCl

How can one determine if a molecule not polar?

The bonds wont be polar

What happens to opposing dipoles? What is the overall polarity of the molecule?

Opposing dipoles cancel No net dipole movement - not polar

What are the properties of Giant Covelant Structure?

- Contain many atoms - Can be similar to an ionic lattice - Properties depend on structure

Give 4 examples of giant ionic structures

1. Diamond 2. Silicon Dioxide 3. Graphite 4. Carbon nanotube

Compare state in covelant and ionic compounds

Covelant - Solid, liquids and gases Ionic - Crystalline solids (Note: There are many counterexamples but most compounds obey these rules)

Compare melting and boiling points of covelant and ionic compound

Covelant - Depends on size and intermolecular bonding Ionic - High (Note: There are many counterexamples but most compounds obey these rules)

Compare conductivity of covelant and ionic compounds

Covelant - Often poor. Depends on size and delocalisation of electrons Ionic - Good when molten (Note: There are many counterexamples but most compounds obey these rules)

Compare solubility of covelant and ionic compounds

Covelant - Depends on intermolecular bonding Ionic - Many soluble in water but not in non-polar solvents (Note: There are many counterexamples but most compounds obey these rules)