Module 2 Chapter 6\

Question 1

What are properties of a chemical bond

Answer 1

They have a definite direction and length

Question 2

What do these properties mean

Answer 2

That molecules have a distinct shape

Question 3

What determines the shape of a molecule

Answer 3

Repulsion between electrons in the outer shell determine its shape. The electron pairs repel so they are as far from each other as possible.

Question 4

What is the order from least to most repulsive in electron pair repulsion theory

Answer 4

Bonded pair to bonded pair, bonded pair to lone pair, lone pair to lone pair

Question 5

What are the rules in shape determination

Answer 5

Lone electron pairs repel greater than bonded pairs.
Lone and bonded pairs are involved in shape determination.

Question 6

What is a multiple bond considered as in electron pair repulsion theory

Answer 6

It is considered as a single pair

Question 7

What are the features of a tetrahedral structure

Answer 7

4 bonded pairs, 0 lone pairs
Bond angle - 109.5

Question 8

What is an example of a tetrahedral structure

Answer 8

Methane

Question 9

What are the features of a pyramidal structure

Answer 9

3 bonded pairs and one lone pair
Bond angle 107 degrees

Question 10

What is an example of a pyramidal structure

Answer 10

Ammonia

Question 11

What are the features of a bent structure

Answer 11

2 bonded pairs, 2 lone pairs
bent angle = 104.5

Question 12

What is an example of a bent structure

Answer 12

Water

Question 13

What are the features of a linear structure

Answer 13

Bond angle - 180*

Question 14

What is an example of a linear structure

Answer 14

Carbon dioxide

Question 15

What are the features of an octahedral structure

Answer 15

Bond angle 90*

Question 16

Example of an octahedral structure

Answer 16

Sulfur hexafluoride

Question 17

What are the features of a trigonal plantar structure

Answer 17

Bond angle 120*
they are all in the same plane

Question 18

What is an example of a trigonal planear structure

Answer 18

Boron triflouride

Question 19

What is the shape of carbonate and nitrate ions

Answer 19

They are trigonal planear

Question 20

What is the shape of a sulfate ion

Answer 20

It’s tetrahedral

Question 21

How do you represent the different bonds

Answer 21

Solid wedge - coming towards you (out of the page)
Dotted wedge - going away from you (into page)
normal line - in the plane of the page

Question 22

What is electronegativity

Answer 22

The ability of an atom to attract the bonding electrons in a covalent bond

Question 23

What is the scale that is used to measure electronegativity

Answer 23

The Qualitative Pauling scale gives a measure of electronegativity where the higher the number the higher the electronegativity

Question 24

What is the general rule for electronegativity

Answer 24

It increases across the period and up a group (doesn’t include noble gases)

Question 25

What are the 3 factors affecting electronegativity

Answer 25

Number of protons Atomic radius Electron shielding

Question 26

How does number of protons affect electronegativity

Answer 26

The more protons you have in the nucleus the stronger the force of attraction

Question 27

how does atomic radius affect electronegativity

Answer 27

The closer the bonding pair to the nucleus the stronger the attraction (as distance from nucleus increases the force of attraction decreases)

Question 28

What is electron shielding and how does it affect electronegativity

Answer 28

Electron shielding is the repulsion of the bonding pair by electrons in the inner shells between the nucleus and bonding pairs, the more shells between the bonding pairs and nucleus the weaker the attraction is.

Question 29

What affects whether the bond is ionic or covalent

Answer 29

If the difference in electronegativity is not that big. The electron won’t be taken completely like in ionic bonds.

Question 30

What are non-polar bonds

Answer 30

They occur when the electron pair is shared equally. It’s when both elements bonded have the same electronegativity. In most cases this is due to them being the same element.

Question 31

What are polar bonds

Answer 31

When one element in the molecule has a greater attraction for the bonded pair of electrons than the other elements. This leads to charge separation.

Question 32

What is the symbol for the partial positive and negative charges

Answer 32

delta positive and delta negative

Question 33

What forms as a result of bond polarisation

Answer 33

Permanent dipoles form as a result of bond polarisation.

Question 34

What is a characteristic of dipoles

Answer 34

They have a direction and magnitude

Question 35

What do polar bonds not always mean

Answer 35

polar bonds don’t always mean that the molecule is polar

Question 36

What is the difference between a polar and non-polar molecule

Answer 36

Polar molecules have a net dipole movement (as the dipoles don’t cancel each other out). Whereas non polar molecules don’t have a net dipole movement (as the dipoles cancel each other out).

Question 37

What are the three types of intermolecular forces

Answer 37

Permanent dipole - dipole interaction Induced dipole - dipole interaction Hydrogen bonds

Question 38

Where are intermolecular forces present

Answer 38

They are only present between covalent molecules

Question 39

What is the relative strength of an intermolecular force compared to a covalent bond

Answer 39

Covalent bond - strong Intermolecular forces - weak

Question 40

How is an instantaneous dipole formed

Answer 40

The electrons are mobile The electrons have a negative charge We could get a molecule with slightly more electrons on one side of the molecule than the other side of the molecule So a dipole has spontaneously come into existence

Question 41

What is an induced dipole

Answer 41

These dipoles are temporary The movement of electrons produces a changing dipole in a molecule At any instant, an instantaneous dipole will exist, but it’s position is constantly switching The instantaneous dipole induces a dipole on a neighbouring molecule The induced dipole induces a further dipole on a neighbouring molecule, which then attract on another.

Question 42

What is a permant dipole interaction

Answer 42

They are within the molecules where the dipole within the molecule is fixed The difference in electronegativity is so great that one is always pulling stronger than the other An intermolecular force then forms between the positively dipole of one molecule and the negatively charged dipole of another molecule.

Question 43

What is hydrogen bonding

Answer 43

A type of permanent dipole - dipole interaction

Question 44

What are the conditions needed for hydrogen bonding to occur

Answer 44

One molecule has to contain a highly polarised H atom. The other molecule must have a small, electronegative atom, with lone pairs of electrons.

Question 45

What is the property of hydrogen that allows this to happen

Answer 45

H is small and can get very close to the other small atom, hence the strong attraction.

Question 46

What are metallic bonds

Answer 46

The strong electrostatic force of attraction between the sea of delocalised electrons and the positive metal cations in the lattice.

Question 47

Where do the delocalised electrons come from

Answer 47

The delocalised electrons come from the outer shell of the metal, where it looses the electrons to form a full outer shell of electrons.

Question 48

What causes metallic bonds to be stronger

Answer 48

The size of the positive charge on the ion The size of the metal ion The number of mobile electrons