Topic 4: Bonding

Question 1

what are exceptions to the octet rule?

Answer 1

• hydrogen
• helium
• beryllium
• Boron
• elements from period 3 onwards

Question 2

What type of bonding occurs with an electronegativity difference of 0-0.4?

Answer 2

non-polar covalent

Question 3

What type of bonding occurs with an electronegativity difference of 0.5-1.7?

Answer 3

polar covalent

Question 4

What type of bonding occurs with an electronegativity difference of ≥1.8?

Answer 4

ionic

Question 5

what is ionic bonding?

Answer 5

the electrostatic attraction between oppositely charged ions

Question 6

what type of elements do ionic bonds form form?

Answer 6

metal and non-metal

Question 7

what are the physical properties of ionic compounds?

Answer 7

• conducts electricity in molten/dissolved state
• high melting point
• soluble in polar solvents

Question 8

why do ionic compounds only conduct electricity in molten state?

Answer 8

the ions are free to move and carry the electric current.

Question 9

what is covalent bonding?

Answer 9

The electrostatic attraction between positive nuclei and a shared pair of bonding electrons.

Question 10

what type of elements do covalent bonds form form?

Answer 10

non-metal

Question 11

what factors do the polarity of a molecule depend on?

Answer 11

• presence of polar bonds
• geometry of molecule

Question 12

what states are simple molecular compounds mostly in + why?

Answer 12

liquids and gases due to weak intermolecular forces

Question 13

what is the electrical conductivity strength of simple molecular substances?

Answer 13

poor conductors of electricity

Question 14

what are the physical properties of giant covalent structures?

Answer 14

• do not form discrete molecules
• do not conduct electricity
• insoluble
• high melting pt.

Question 15

what are allotropes?

Answer 15

different forms of the same element in the same physical state

Question 16

what are the allotropes of carbon?

Answer 16

• graphite
• diamond
• fullerene C60
• graphene

Question 17

what is the structure of graphite?

Answer 17

• layers held together by weak intermolecular forces
• Each carbon atom is bonded to 3 other carbon atoms.
• Bond angle: 120
• Geometry: trigonal planar

Question 18

what are the physical properties of graphite?

Answer 18

• layers can slide over one another
• good conductor of electricity

Question 19

why is graphite a good conductor of electricity?

Answer 19

the delocalised electrons
that are free to move within the structure

Question 20

what is the structure of diamond?

Answer 20

• Giant covalent structure
• Each carbon is bonded to 4 other carbon atoms
• bond angle: 109.5
• Geometry: tetrahedral

Question 21

what is one physical property of diamond?

Answer 21

• does not conduct electricity

Question 22

what is the structure and physical properties of fullerene?

Answer 22

• Each carbon atom is bonded to 3 other carbon atoms
• Structure consists of 12 pentagons and 20 hexagons.
• some electrical conductivity

Question 23

what is the structure and physical properties of fullerene?

Answer 23

• Each carbon atom is bonded to 3 other carbon atoms.
• Bond angle between carbon atoms is 120
• Very good heat and electrical conductivity.
• Very thin (one layer thick) but also very strong.

Question 24

what are london dispersion forces?

Answer 24

weak, temporary forces that arise due to the random movement of electrons

Question 25

What are Dipole-Dipole Interactions?

Answer 25

attractions between polar molecules, where the positive end of one molecule is attracted to the negative end of another.

Question 26

What is Hydrogen Bonding?

Answer 26

hydrogen covalently bonded to F, O, N

Question 27

London dispersion forces increases with increasing ………. ………….

Answer 27

molar mass

Question 28

what is metallic bonding?

Answer 28

the electrostatic attraction between a lattice of positive ions and delocalized electrons.

Question 29

what does strength of metallic bonds depend on?

Answer 29

• charge of the ions
• radius of the metal ion

Question 30

why are metals malleable?

Answer 30

the metallic bond remains intact even if the structure is distorted.

Question 31

why are metals reflective?

Answer 31

the delocalized electrons in the metallic structure reflect
light

Question 32

what is the relationship between the strength of metallic bond and ionic charge?

Answer 32

stronger ionic charge = stronger bond

Question 33

what is the relationship between the strength of metallic bond and size of radius?

Answer 33

smaller radius = stronger bond

Question 34

what are alloys?

Answer 34

materials that are composed of two or more metals or a metal and a non-metal.

Question 35

why are alloys less malleable?

Answer 35

The added metal atoms can distort the lattice structure making it more difficult for the layers to slide over each other.

Question 36

what is a sigma bond?

Answer 36

head-on overlap of s orbitals