3.1.3 Bonding

Question 1

What does ionic bonding involve?

Answer 1

• Strong electrostatic attraction/forces.
• Between oppositely charged ions.
• In a giant ionic lattice.

Question 2

What are the formulas of the following compound ions?
Sulfate, hydroxide, nitrate, carbonate and ammonium.

Answer 2

SO4^2-
OH^-
NO3^-
CO3^2-
NH4^+

Question 3

What is a covalent bond?

Answer 3

Contains a shared pair of electrons.
(Represented by a line)

Question 4

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

Answer 4

Contains a shared pair of electrons with both electrons supplied by one atom.
(Represented by an arrow)

Question 5

What does metallic bonding involve?

Answer 5

• Strong electrostatic attraction/forces.
• Between sea of delocalised electrons and positive metal ions.
• In a giant metallic lattice.

Question 6

Draw the ionic crystal structure of sodium chloride (8 particles).

Answer 6

Physical Flashcards

Question 7

Draw the metallic crystal structure of magnesium.

Answer 7

Physical Flashcards

Question 8

Draw the molecular crystal structure of iodine.

Answer 8

Physical Flashcards

Question 9

Draw the molecular crystal structure of ice.

Answer 9

Physical Flashcards

Question 10

Draw the macromolecular crystal structure of diamond.

Answer 10

Physical Flashcards

Question 11

Draw the macromolecular crystal structure of graphite.

Answer 11

Physical Flashcards

Question 12

What are the properties of ionic compounds?

Answer 12

Mp/bp: High
- Giant ionic lattice
- Strong electrostatic forces of attraction between oppositely charged ions
- Require lots of energy to overcome

Solubility in water: Generally good

Conductivity:
Poor when solid - ions fixed in lattice
Good when liquid - ions free to move and carry a charge through the structure

Question 13

What are the factors affecting strength of an ionic bond?

Answer 13

1. Size of ion
   - The smaller the ion, the stronger the bond
2. Charge of ion
   - The higher the charge, the stronger the bond

Question 14

What are the properties of metals?

Answer 14

Mp/bp: High
- Giant metallic lattice
- Strong electrostatic forces of attraction between positive metal ions and sea of delocalised electrons
- Require lots of energy to overcome

Solubility in water: Insoluble

Conductivity: Good
- Delocalised electrons free to move and carry a charge through the structure

Malleable
- Positive ions in lattice identical
- Planes of ions can slide easily over one another

Question 15

What are the factors affecting strength of a metallic bond?

Answer 15

1. Number of protons/strength of nuclear attraction
   - The more protons, the stronger the bond
2. Number of delocalised electrons per atom (the outer shell electrons are delocalised)
   - The more delocalised electrons, the stronger the bond
3. Size of ion
   - The smaller the ion, the stronger the bond

Question 16

What are the properties of macromolecular substances?

Answer 16

Mp/bp: High
- Many strong covalent bonds
- In giant molecular / macromolecular structure
- Require lots of energy to overcome

Solubility in water: Insoluble

Conductivity:
Diamond poor - electrons localised / can’t move
Graphite good - delocalised electrons between layers free to move and carry a charge through the structure

Question 17

What are the properties of molecular substances?

Answer 17

Mp/bp: Low
- Weak intermolecular forces between molecules (specify type)
- Don’t require a lot of energy to overcome

Solubility in water: Generally poor

Conductivity: Poor
- No ions or delocalised electrons free to move and carry a charge through the structure

Question 18

What is the shape and bond angle of a molecule with 2 BP and 0 LP?

Answer 18

Physical Flashcards

Question 19

What is the shape and bond angle of a molecule with 3 BP and 0 LP?

Answer 19

Physical Flashcards

Question 20

What is the shape and bond angle of a molecule with 4 BP and 0 LP?

Answer 20

Physical Flashcards

Question 21

What is the shape and bond angle of a molecule with 3 BP and 1 LP?

Answer 21

Physical Flashcards

Question 22

What is the shape and bond angle of a molecule with 2 BP and 2 LP?

Answer 22

Physical Flashcards

Question 23

What is the shape and bond angle of a molecule with 5 BP and 0 LP?

Answer 23

Physical Flashcards

Question 24

What is the shape and bond angle of a molecule with 6 BP and 0 LP?

Answer 24

Physical Flashcards

Question 25

What is the shape and bond angle of a molecule with 4 BP and 2 LP?

Answer 25

***Physical Flashcards***

Question 26

How do you explain the shape of a molecule?

Answer 26

1. State the shape and bond angle 2. State that electron pairs arrange themselves as far apart as possible to minimise repulsion. 3. If no lone pairs present state that the electron pairs repel equally. 4. If lone pairs present, identify which pair repulsion is occurring and state that lp-lp repulsion is greater than lp-bp repulsion, which is greater than bp-bp repulsion.

Question 27

What is electronegativity?

Answer 27

The power of an atom to attract the pair of electrons in a covalent bond to itself.

Question 28

What is a polar covalent bond?

Answer 28

- In a covalent bond between elements with different electronegativities - The more electronegative element will become δ- and the other element will become δ+ - The electron distribution / electron density will be unsymmetrical / uneven

Question 29

Where are van der waals intermolecular forces found?

Answer 29

Between all molecules.

Question 30

Where are permanent dipole-dipole intermolecular forces found?

Answer 30

Between polar molecules.

Question 31

Why do some molecules with polar bonds not form permanent dipole-dipole intermolecular forces?

Answer 31

- The molecule is symmetrical / planar - Indivdual bond dipoles cancel out - So the molecule is net non-polar

Question 32

Where are hydrogen bond intermolecular forces found?

Answer 32

Between polar molecules with bond between H and lone pair on O/N/F.

Question 33

How do van der waals forces arise between molecules?

Answer 33

- (Random) movement of electrons forms a temporary dipole (in one molecule) / an imbalance in electron density - Induces a dipole in another molecule - (These temporary) dipoles in different molecules attract / attraction between δ+ and δ- in different molecules

Question 34

What is the order of strength of intermolecular forces?

Answer 34

1. Hydrogen bonding 2. Permanent dipole-dipole forces 3. Van der waals forces

Question 35

Explain why tetrachloromethane has a higher boiling point than dichloromethane.

Answer 35

- Van der Waals' forces between molecules in CCl4 stronger than (combined van der Waals' and) dipole-dipole forces between molecules in CH2Cl2 - As CCI4 has (many) more electrons than CH2Cl2