Chemical Bonding Flashcards

1
Q

What is an ionic bond?

A

Electrostatic forces of attraction between oppositely-charged ions

Ionic bonds are non-directional.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a covalent bond?

A

Electrostatic forces of attraction between a shared pair of electrons and positively charged nuclei.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a metallic bond?

A

Electrostatic forces of attraction between a lattice of positive ions and a sea of delocalised electrons.

Metallic bonds are non-directional.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What determines the strength of an ionic bond?

A

Charge density, which affects Lattice energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What determines the strength of a metallic bond?

A

Charge density of cations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What determines the strength of a covalent bond?

4 factors

A

1) Effectiveness of atomic orbital overlap (how diffuse orbital is)
2) Number of bonds
3) Polarity
4) Presence of neighbouring lone pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a coordinate/dative bond? What are the requirements for one to form?

A

A bond where the shared pair of electrons is only provided by one of the bonding atoms.

The donating atom must have a lone pair of electrons, and the receiving atom must have a vacant, low-lying orbital to accept the electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Determine and explain the shape of SF4

State its bond angle.

A

Since SF4 has four bond pairs of ELECTRONS and one lone pair OF ELECTRONS, it has
Trigonal bipyrimidal
See-saw, since it has one lone pair.
107 degrees.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Determine and explain the shape of PCl5

State its bond angle.

A

Trigonal bipyrimidal, since it has five regions of electron density and no lone pairs.
120 degrees on equatorial plane, 90 degrees from axial to equatorial.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Determine and explain the shape of SF6

State its bond angle.

A

Octahedral, since it has six regions of electron density and no lone pairs.
90 degrees.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Bond angle of tetrahedral

A

109.5 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Draw IF2-

A

Linear with two lone pairs and a -1 charge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Bond angle of trigonal planar

A

120 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Determine and explain the shape of H2O

State its bond angle.

A

Tetrahedral, four regions of electron density.
Bent, two lone pairs.
105 degrees.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Draw SO3

A

Trigonal planar shape with every bond being S=O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Draw BH4

A

Tetrahedral, all B-H bonds.

17
Q

VSEPR is used to predict the molecular geometry of a species where electron pairs around the central atom of a molecule are arranged as far apart as possible in space so as to minimise their repulsion.

A

just know that ig

18
Q

Why does PCl5 exist and not NCl5?

A

P is an element in Period 3 with vacant, low-lying 3d orbitals that can accept more electrons and expand octet, while N in Period 2 has no such available orbitals and can only accommodate a maximum of 8 valence electrons.

19
Q

Compare bond angles of tetrahedral, trigonal pyrimidal and bent

A

In tetrahedral the bond angle is the greatest at 109.5 degrees because it has 4 bond pairs and exhibits only bond pair-bond pair repulsion.

In trigonal pyrimidal it has 3 bond pairs and 1 lone pair. Lone pair-bond pair repulsion is greater than bond pair-bond pair repulsion, so the bond angle decreases to 107 degrees.

In bent, it has 2 bond pairs and 2 lone pairs. Lone pair-lone pair repulsion is greater than lone pair-bond pair and bond pair-bond pair repulsion, so the 2 lone pairs repel the bond pairs even more to 105 degrees.

20
Q

A molecule is said to be polar when…

A

A molecule is polar when its overall net dipole is zero.

21
Q

Why is there an unpaired electron in NO and NO2?

A

They are radicals

22
Q

Name and rank the three types of intermolecular forces by strength.

A

Instantaneous dipole-induced dipole (weakest)
Permanent dipole-permanent dipole
Hydrogen bonding (actually a stronger form of pdpd)

23
Q

How do idid interactions arise?

A

Idid interactions are caused by momentary movements of electron charge in atoms. They are present between all particles, including non-polar molecules.

24
Q

Factors affecting strength of idid interactions

A

1) Electron cloud size (Polarisability)

2) Surface of area for molecular interaction

25
Q

How do pdpd interactions arise?

A

Electrostatic attraction between the partial positive dipoles of molecules and partial negative dipoles

26
Q

Factors affecting strength of pdpd interactions

A

Polarity (difference in electronegativity)

27
Q

How do hydrogen bonds arise?

A

When a H atom is covalently bonded to highly electronegative F, O or N and there is a lone pair of electrons on a neighbouring F, O or N that can attract the partial positive charge on H

28
Q

Factors affecting strength of hydrogen bonds

A

1) Extensiveness of hydrogen bonding
2) Strength of hydrogen bonds

3) Overall electron cloud size

29
Q

Why is ice less dense than water?

A

In ice, each oxygen atom is tetrahedrally bonded to 4 hydrogen atoms, 2 by covalent bonds and 2 by hydrogen bonds. This forms a highly-ordered 3D structure that is rigid and open, causing it to be less dense than water.

30
Q

Why does 2-nitrophenol have a lower boiling point and solubility in water than 4-nitrophenol?

A

2-nitrophenol has lower boiling point and solubility due to intramolecular hydrogen bonding.
Less sites available for intermolecular hydrogen bonding

31
Q

What are the conditions for a solute to be able to dissolve in a solvent?

A

Solute-solvent interactions must be stronger than or similar to that of solute-solute interactions and solvent-solvent interactions.

Energy released by forming solute-solvent interactions must be enough to compensate for energy absorbed in breaking sol-sol and solv-solv interactions.

32
Q

Why do ionic solids dissolve in water?

A

Ionic solids dissolve because a large amount of energy is released from ions forming strong ion-dipole interactions which compensate for energy required to overcome strong ionic bonds in solid.

33
Q

What is bond energy?

A

Amount of energy required to break 1 mole of covalent bond between two atoms in the gaseous state,

34
Q

What is bond length?

A

Distance between the nuclei of two covalently bonded atoms