Covalent bonds in simple molecules, ions & ionic bonding

Question 1

What is valency?

Answer 1

Equal to the number of atoms of H that the atom/group could combine with/displace in forming compounds.

Question 2

What are valence electrons?

Answer 2

Electrons in the outermost shell.

Question 3

What is the Octect Rule?

Answer 3

In stable molecules, atoms share valence electrons in the numbers required to achieve filled out shells.

Question 4

List the important anions

Answer 4

OH- (hydroxide)
CO3 2- (carbonate)
COO- (carboxylate)
NO3 - (nitrate)
NO2 - (nitrite)
PO4 3- (phosphate)
SO4 2- (sulfate)

Question 5

List the important cations

Answer 5

Na+
K+
Ca+
NH4 +
OH3 + (hydronium)

Question 6

What is a Lewis structure?

Answer 6

H
|
H - C - H
|
H

Question 7

What are resonance hybrids?

Answer 7

2 or more possible Lewis structures of a molecule with the same atom positions but differing locations of some electron pairs.

Question 8

What is bond length?

Answer 8

The distance between the nuclei of two covalently bonded atoms.

Question 9

What is bond dissociation energy?

Answer 9

The energy required to break the given bond.

Question 10

How is bond length associated with bond dissociation energy?

Answer 10

In a covalent bond, the 2 atoms are held together as both nuclei are attracted to the same pair of electrons.

Inversely proportional
- longer bond, lower energy as attraction is weaker between nuclei due to distance

Question 11

What are the properties of ionic bonds?

Answer 11

Conductors
High melting point

Question 12

What are non-polar covalent bonds?

Answer 12

Electrons shared equally.
No charges on atoms

Question 13

What are polar covalent bonds?

Answer 13

Electrons shared unequally
(due to electronegativity, so electrons pulled closer to an atom).
Partial charges on atoms

Question 14

What is an example of a polar molecule?

Answer 14

Water - O more electronegative than H so electrons pulled closer to O.
Resulting in partial - charge.

Question 15

What is the difference between intermolecular and intramolecular?

Answer 15

Inter - forces that exist between molecules.
Intra - forces holding atoms within a molecule together.

Question 16

What types of intermolecular forces are there?

Answer 16

Dispersion forces
Dipole-dipole interactions
Steric repulsion
Hydrogen bonds
Hydrophobic forces

Question 17

What types of intramolecular forces are there?

Answer 17

Ionic interactions

Question 18

What are dipole-dipole interactions?

Answer 18

Interactions between the - pole of polar molecule and + pole of another molecule.
Permanent, temporary or induced.

Question 19

What are dispersion forces?

Answer 19

Temp dipoles caused by movement of electrons in a molecule.

• Directly proportional
• More electrons, larger dipole + stronger force

Question 20

What are hydrogen bonds?

Answer 20

WEAK interaction
H atom covalently bonded to electronegative atom.

H atom can only form a H bond with a lone pair on another electronegative atom.

Question 21

What is a intermolecular hydrogen bond?

Answer 21

H bond formed between two molucles.

Question 22

What is a intramolecular hydrogen bond?

Answer 22

H bond formed between two different atoms in same molecule.

Question 23

What are ionic interactions?

Answer 23

NOT same as ionic bond.

Attractive forces that exist between ionic species.

Question 24

What is steric repulsion?

Answer 24

Arrangement of atoms in a molecule.

Affects rates + activation energies of most chemical reactions.

Question 25

What is Van Der Waals?

Answer 25

WEAK interaction

Overall interaction between two molecular species once the dispersion forces + dipolar interactions and steic repulsion force are taken into accout.