1.3- Bonding

Question 0

What makes ionic bonding stronger and melting points higher?

Answer 0

Smaller ions

Higher charges

Question 1

What is an ionic bond?

Answer 1

Electrostatic force of attraction between oppositely charged ions formed by electron transfer

Question 2

What is a covalent bond?

Answer 2

A shared pair of electrons

Question 3

What is a dative covalent bond?

Answer 3

When the shared pair of electrons in the covalent bond come from only one of the bonding atoms

Question 4

What is a metallic bond?

Answer 4

Electrostatic force of attraction between the positive metal ions and the delocalised electrons

Question 5

Three factors affecting the strength of a metallic bond?

Answer 5

Number of protons/strength of nuclear attraction

Number of delocalised electrons per atom

Size of ion

Question 6

What are the properties of ionic bonding?

Answer 6

High melting and boiling points because of giant lattice of ions with strong electrostatic forces between oppositely charged ions

Generally good solubility in water

Poor conductors when solid as ions can’t move/fixed in the lattice

Good conductors when molten as ions are free to move

Usually crystalline solids

Question 7

What are the properties of simple molecular substances?

Answer 7

Low melting and boiling points because of weak intermolecular forces between molecules (specify type of bonding)

Generally poor solubility in water

Poor conductors when solid as there are no ions to conduct and electrons are localised

Poor conductors when molten as there are no ions

They are mostly gases and liquids

Question 8

What are the properties of macromolecular substances?

Answer 8

High melting and boiling points because of many strong covalent bonds in the macromolecular structure. Take a lot of energy to break the many strong bonds

They are insoluble in water

Diamond and sand are poor conductors when solid because electrons are localised

Graphite is a good conductor when solid because there are delocalised electrons between layers

Poor conductors when molten

Generally solids

Question 9

What are the properties of metallic substances?

Answer 9

High melting and boiling points as strong electrostatic forces between positive ions and sea of delocalised electrons

Insoluble in water

Good conductors when solid as the delocalised electrons can move through the structure

Good conductors when molten

Malleable as the positive ions in the lattice are all identical so the planes of ions can slide easily over one another. Attractive forces in the lattice are the same whichever ions are adjacent

Generally shiny metals

Question 10

Linear shape?

Answer 10

2 bonding pairs, 0 lone pairs

180°

Question 11

Trigonal planar?

Answer 11

3 bonding pairs, 0 lone pairs

120°

Question 12

Tetrahedral shape?

Answer 12

4 bonding pairs, 0 lone pairs

109.5°

Question 13

Trigonal pyramidal?

Answer 13

3 bonding pairs, 1 lone pair

107°

Question 14

Bent/Angular?

Answer 14

2 bonding pairs, 2 lone pairs

104.5°

Question 15

Trigonal Bipyramidal?

Answer 15

5 bonding pairs, 0 lone pairs

120° and 90°

Question 16

Octahedral shape?

Answer 16

6 bonding pairs, 0 lone pairs

90°

Question 17

How to explain the shapes of molecules?

Answer 17

State the number of bonding and lone pairs of electrons

State that electron pairs repel and try to get as far apart as possible (position of minimum repulsion)

If there are no lone pairs state that the electron pairs repel equally

If there are lone pairs state that the lone pairs repel more than bonding pairs (reduce bond angles by 2.5° per lone pair)

State the actual shape and bond angle

Question 18

Steps to work out shapes of molecules?

Answer 18

Count number of outer shell electrons of the central atom

Add that to number of electrons the bonding atoms bring

Add/remove electrons depending on the charge of the molecule

Divide total number by two to find electron pairs

Look at molecule to decide how many bonding and lone pairs and then decide the shape

Question 19

What is electronegativity?

Answer 19

The relative tendency of an atom in a covalent bond in a molecule to attract electrons in a covalent bond to itself

Question 20

What are the trends in electronegativity?

Answer 20

Increases across a period as the number of protons increases and the atomic radius decreases because the electrons in the same shell are pulled in more

Decreases down a group because the distance between the nucleus and the outer electrons increases and the shielding of inner shell electrons increases

Question 21

What is a polar bond?

Answer 21

A covalent bond in which the electron pair is not shared equally. Thus creating partial charges (dipoles)

Question 22

What is a non-polar bond?

Answer 22

A covalent bond in which the electron pair is shared equally

Question 23

What are intermolecular forces?

Answer 23

A physical attraction between molecules

Question 24

Permanent dipole-dipole bonding?

Answer 24

Attraction between two polar molecules (dipoles)

Question 25

What are van der Waals forces?

Answer 25

Attraction between temporary dipoles caused by the movement of electrons in the atoms of a molecule

Question 26

What is hydrogen bonding?

Answer 26

Attraction between polar molecules that contain hydrogen atoms bonded to one of these atoms:
F, O, N, Cl

Central atom must have an available lone pair of electrons