Bonding And Structure

Question 1

What are the 3 main types of chemical bonds?

Answer 1

Ionic
Covalent
Metallic

Question 2

Define ionic bonding

Answer 2

The electrostatic attraction between positive and negative ions.

Question 3

Give an example of an ironically bonded substance

Answer 3

NaCl salt

Question 4

Define covalent bonding

Answer 4

Electrostatic attraction between a shared pair of electrons and the nuclei

Question 5

Define metallic bonding

Answer 5

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

Question 6

Why does giant ionic lattices conduct electricity when liquid but not solid?

Answer 6

In solid state the ions are in fixed positions and therefore can’t move.
When they are in liquid state the ions are mobile and thus can freely carry the charge.

Question 7

Giant ionic lattices have a high melting point, why?

Answer 7

Large amount of energy is required to overcome the strong electrostatic bonds.

Question 8

In what type of solvents do ionic lattices dissolve?

Answer 8

Polar solvents

Question 9

Why are ionic compounds soluble in water?

Answer 9

Water has a polar bond, hydrogen atoms have a positive charge and oxygen atoms have a negative charge. These charges are able to attract the charges ions.

Question 10

What is it called when atoms are bonded by a single pair of shared electrons?

Answer 10

Single bond

Question 11

How many covalent bonds does carbon form?

Answer 11

4

Question 12

How many covalent bonds does oxygen form?

Answer 12

2

Question 13

What is a lone Pair?

Answer 13

Electrons in the outer shell that are not involved in the bonding

Question 14

What is formed when atoms share 2 pairs of electrons?

Answer 14

Double bond

Question 15

What is formed when atoms share 3 pairs of electrons?

Answer 15

Triple bond

Question 16

What is average bond Enthalpy ?

Answer 16

Measure the average energy needed to break the bond

Question 17

What is a dative covalent bond?

Answer 17

A bond where both of the shared electrons are supplied by one atom

Question 18

How are oxoniums ions formed?

Answer 18

Formed when acid is added to water H3O+

Question 19

What does expansion of the octet mean?

Answer 19

When a bonded atom has more than 8 electrons in the outer shell.

Question 20

What are the types of covalent structure?

Answer 20

Simple molecular lattice

Giant covalent lattice

Question 21

Describe the bonding in simple molecular structures

Answer 21

Atoms within the same molecule are held by strong covalent bonds and different molecules are held by weak intermolecular forces.

Question 22

Why do simple molecular structures have low melting and boiling points?

Answer 22

Small amount of energy is enough to overcome the intermolecular forces.

Question 23

Can simple molecular structures conduct electricity ?

Answer 23

No because they have no free charged particles to move around.

Question 24

What type of solvent do simple molecular structures dissolve in?

Answer 24

Non polar

Question 25

Give examples of giant covalent structures

Answer 25

Diamond Graphite Silicon dioxide

Question 26

List some properties of giant covalent structures ?

Answer 26

High melting and boiling points. Non conductors of electricity except graphite Insoluble in polar and no polar solvents

Question 27

How does graphite conduct electricity?

Answer 27

Delocalised electrons present between the layers are able to move freely carrying the charge

Question 28

Why do giant covalent structures have Hugh melting and boiling points?

Answer 28

String covalent bonds within the molecules need to be broken which requires a lot of energy

Question 29

Draw and describe the structure of a diamond

Answer 29

3D tetrahedral structure of c atoms bonded with 4 other c atoms

Question 30

What does the shape of a molecule depend on?

Answer 30

Number of electron pairs in the outer shell | Number of these electrons which are bonded and lone pairs

Question 31

By how many degrees does each lone pair reduce the bond angle?

Answer 31

2.5

Question 32

Define electronegativity

Answer 32

The ability of an atom to attract the pair of electrons (the electron density) in a covalent bond.

Question 33

In which direction of the periodic table does electronegativity increase?

Answer 33

Top right, towards fluorine

Question 34

What does it mean when the bond is non-polar?

Answer 34

The electrons in the bond are evenly distributed

Question 35

What is the most electronegative element?

Answer 35

Fluorine

Question 36

How is a polar bond formed?

Answer 36

Binding atoms have different electronegativities

Question 37

Why is water polar but carbon dioxide is not?

Answer 37

Calvin dioxide is a symmetrical molecule, so therefore there is no overall dipole

Question 38

What is meant by intermolecular force?

Answer 38

Attractive force between neighbouring molecules?

Question 39

What are the 2 types of intermolecular forces?

Answer 39

Hydrogen bonding Permanent dipole permanent dipole forces Permanent dipole - induced dipole forces

Question 40

What is the strongest type of intermolecular forces?

Answer 40

Hydrogen bonding

Question 41

Describe permanent dipole - induced dipole interactions

Answer 41

When a molecule with a permanent dipole is close to the non polar molecules it causes the non polar molecule to become slightly polar leading to attraction.

Question 42

How does graphite conduct electricity?

Answer 42

Delocalised electrons are present between the layers and are able to move freely carrying the charge.

Question 43

Describe permanent dipole-dipole interactions

Answer 43

Some molecules with polar bonds have permanent dipoles. These forces of attraction between those dipoles and those of neighbouring molecules.

Question 44

Describe London forces

Answer 44

London forces are caused by random movements of electrons. This leads to instantaneous dipoles Instantaneous dipole induce a dipole on nearby molecules. Induced dipoles attract one another

Question 45

Are London forces greater in smaller or larger molecules?

Answer 45

Larger due to more electrons

Question 46

Does boiling point increase down the noble gas group? Why?

Answer 46

B.p increases because the number of electrons increases and hence the strength of London forces also increases.

Question 47

What conditions are needed for hydrogen bonding to occur?

Answer 47

O-H N-H F-H bind Lone pair of electrons on O,F,N Because O, N,F at highly electronegative, the hydrogen nucleus is left exposed. Strong force of attraction between the hydrogen nucleus and lone polar of electrons on N,O,F

Question 48

Why is ice less dense than liquid water

Answer 48

In ice, the water molecules are arranged in an orderly pattern. It has an open lattice with hydrogen bonds In water the lattices is collapsed and the molecules are closer together,

Question 49

Why does water have a higher melting and boiling point than expected.

Answer 49

Hydrogen bonds are stronger than other intermolecular forces so extra strength is required to overcome the forces.

Question 50

Other important areas in the topic

Answer 50

Shapes of molecules | Drawing if hydrogen bonding