Bonding: extended

Question 1

Lone pair?

Answer 1

Two unbonded electrons in the same orbital of an atom in a molecule.

Question 2

Vacant orbital?

Answer 2

An orbital containing no electrons.

Question 3

Dative Covalent (co-ordinate) bond?

Answer 3

A bond in which the electrons in the shared pair (lone pair) between 2 atoms comes from the same atom. Ammonium is an example.

Question 4

What does VSEPR Theory stand for and define it?

Answer 4

Valence Shell Electron Pair Repulsion Theory. The theory is used to find the shapes and bond angles of covalently bonded molecules and ions.

Question 5

List the properties of a linear shaped molecule.

Answer 5

Such a molecule has 2 electron regions, bond angles of 180 degrees and has a 2D diagram.

Question 6

List the properties of a trigonal planar shaped molecule. What is the lone pair case called?

Answer 6

Such a molecules has 3 electron regions, bond angles of 120 degrees and has a 2D diagram. There exists a case where a lone pair exists and this shape is known as bent with bond angles less than 120 degrees.

Question 7

List the properties of a tetrahedral shaped molecule. What are the lone pair cases called?

Answer 7

Such a molecule has 4 electron regions, bond angles of 109.5 degrees and has a 3D diagram. There exists two cases: pyramidal that has one lone pair with bond angles of less than 109.5 degrees and bent that has two lone pairs with bond angles also less than 109.5 degrees.

Question 8

List the properties of a trigonal bipyramidal shaped molecule.

Answer 8

Such a molecule has 5 electron regions, bond angles of 3 with 120 degrees and 2 with 90 degrees and has a 3D diagram.

Question 9

List the properties of a octahedral shaped molecule.

Answer 9

Such a molecule has 6 electron regions, bond angles of 90 degrees and has a 3D diagram.

Question 10

Non-polar bond?

Answer 10

A covalent bond in which there is no separation of charge.

Question 11

Polar bond?

Answer 11

A covalent bond in which there is a separation of charge.

Question 12

What are the electronegativity ranges for non-polar covalent, covalent and ionic bonding?

Answer 12

Non-polar covalent: ΔEN of 0
Polar covalent: ΔEN of 0.1 - 2.0
Ionic: ΔEN of 2.1 and higher.

Question 13

Hydrogen bonds?

Answer 13

The IMFs formed between molecules of compounds containing H covalently bonded to N, O or F. Hydrogen atoms are very small and are able to partially share the lone pairs on N, O and F. Hydrogen bonds are the strongest of all IMFs.

Question 14

Dipole-Dipole forces?

Answer 14

Bonds that exist between permanent dipoles, only occurring in polar substances.

Question 15

Induced Dipole - Induced Dipole forces?

Answer 15

Bonds that exist between all substances, polar and non-polar. They are generally weak but can be strong between large molecules. Also known as London forces or momentary dipoles.

Question 16

What are the known IMFs in order of strongest to weakest.

Answer 16

Ion-Dipole forces, Hydrogen Bonds, Dipole-Dipole forces, Ion-Induced dipole forces, Dipole-Induced dipole forces and London Forces.

Question 17

What are the unique properties of water?

Answer 17

Ice is less dense than liquid water.
Water has a high melting and boiling point.
Water has a high specific heat capacity, high latent heat of fusion and high latent heat of vaporization.

Question 18

Specific Heat Capacity? What is the value for water?

Answer 18

The energy required to increase the temperature of 1 gram of water by 1 Kelvin. Strong hydrogen bonds give water a larger specific heat capacity than expected. The SHC of water is: 4.18 J.g-¹.K-¹

Question 19

Latent Heat of Fusion? What is the value for water?

Answer 19

The energy absorbed when 1 gram of ice melts (equal to the energy released when 1 gram of water freezes). For water it is: 334 J.g-¹.K-¹

Question 20

Latent Heat of Vaporization? What is the value for water?

Answer 20

The energy absorbed when 1 gram of water evaporates (equal to the energy released when 1 gram of water condenses). For water it is: 2257 J.g-¹.K-¹

Question 21

Bond Length?

Answer 21

Known as the average distance between the nuclei of bonded atoms. A longer bond is a weaker bond, ex: I-I bond is longer and thus weaker than a F-F bond.

Question 22

Bond Order?

Answer 22

Relates to the number of shared pairs in a bond. A higher bond gives a stronger bond order, ex: N☰N is stronger than N-N.

Question 23

What are the types of vibrations for covalently bonded atoms in a molecule? Describe them.

Answer 23

Stretch and compress: Atoms move along a 1D plane and this applies to molecules with 2 or more atoms.
Bending: Atoms move in the 2D plane of the molecule and this applies to molecules with 3 or more atoms.
Wagging: Atoms move in the 3D plane and this applies to molecules with 3 or more atoms.