2.2.2 - Bonding and Structure

Question 1

What does ionic bonding happen between?

Answer 1

A metal and a non metal.

Question 2

Which way are electrons transferred?

Answer 2

From the metal atom to the non-metal atom.

Question 3

What holds ionic compounds together?

Answer 3

Oppositely charged ions are formed, which are bonded together by strong electrostatic attraction.

Question 4

In giant ionic lattices what is each ion surrounded by?

Answer 4

Oppositely charged ions.

Question 5

How is a three dimensional giant ionic lattice formed?

Answer 5

Ions attract each other from all directions.

Question 6

Can ionic compounds conduct electricity when solid?

Answer 6

No

Question 7

Why can ionic compounds conduct electricity when in liquid state?

Answer 7

The ions are free to move around and conduct electricity.

Question 8

What is ionic bonding?

Answer 8

electrostaic atracion between positive and negatively charged ions.

Question 9

Why don’t ionic compounds conduct when solid?

Answer 9

Ions are in fixed position and cannot move to carry a charge.

Question 10

Why can ionic compounds conduct when molten or in solution?

Answer 10

Ions are mobile and are therefore able to carry a charge.

Question 11

Why do ionic compounds have high melting and boiling points?

Answer 11

Due to the strong electrostatic force of attraction between positively and negatively charged ions.

Question 12

Why does MgO have require more energy to break down than NaCl?

Answer 12

Mg2+ and O2- bonds are stronger than Na- and Cl- bonds.

Question 13

What do ionic lattices dissolve in?

Answer 13

Polar solvents, such as water.

Question 14

What do polar bonds occur between?

Answer 14

Atoms that do not share electrons equally between them.

Question 15

What is the result of a polar bond?

Answer 15

Results in the atom having very small charges on them.

Question 16

What do polar water molecules do?

Answer 16

Attract the charged ions in the giant ionic lattice.

Question 17

What is covalent bonding?

Answer 17

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

Question 18

What is a dative covalent bond?

Answer 18

A covalent bond in which the shared pair of electrons has been provided by one of the bonding atoms only.

Question 19

What is an example of a substance which contains a dative covalent bond?

Answer 19

Ammonium ion. NH4+

Question 20

What does the average bond enthalpy measure?

Answer 20

The energy required to break a covalent bond.

Question 21

What does a greater average bond enthalpy mean?

Answer 21

The stronger the bond is, therefore more energy is required tot break it.

Question 22

In shapes of molecules what angles are the biggest?

Answer 22

Lone pair lone pair angles

Question 23

In shapes of molecules what angles are the smallest?

Answer 23

Bond pair - bond pair angles.

Question 24

According to electron pair repulsion theory what happens to the bond angle when a lone pair is added?

Answer 24

The distances decreases by 2.5 degrees as the lone pair repels the bond pair.

Question 25

In a linear molecule what is the bond angle?

Answer 25

180

Question 26

If there are three bond pairs and no lone pairs what shape the molecule and what is its bond angle?

Answer 26

Trigonal planar and 120

Question 27

What is the shape of a molecule and bond angle which has four bond pairs and no lone pairs?

Answer 27

Tetrahedral 109.5

Question 28

What is the shape and bond angle of a molecule which has 3 bond pairs and 1 lone pair

Answer 28

Trigonal pyramidal 107

Question 29

What is the shape and bond angle of a molecule which has two bond pair and two lone pairs?

Answer 29

Non linear 104.5

Question 30

What is the shape and bond angle of water?

Answer 30

Non-linear 104.5

Question 31

What is the shape and bond angle of a molecule with 5 electron pairs bonded around the central atom?

Answer 31

Trigonal bipyramidal 90

Question 32

What is the shape and bond angle of a molecule with 6 electron pairs around the central atom?

Answer 32

Octahedral 90

Question 33

What is electronegativity?

Answer 33

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

Question 34

What is the most electronegative element?

Answer 34

Fluorine

Question 35

How does the Pauling scale work?

Answer 35

The higher the value the more electronegative the element is.

Question 36

What makes a bond polar in covalent bonding?

Answer 36

The bonding electrons are pulled towards the more electronegative atom.

Question 37

What is a dipole?

Answer 37

The difference in charge between the two atoms caused by a shift in electron density in the bond.

Question 38

How is a bond more polar?

Answer 38

The greater the difference in electronegativity.

Question 39

Why are diatomic gases non polar?

Answer 39

Because both atoms have equal negativity and so electrons are attracted equally to both nuclei.

Question 40

Why are carbon and hydrogen ann-polar?

Answer 40

They have pretty similar electronegativity.

Question 41

What do polar bonds have?

Answer 41

Permanent dipoles.

Question 42

What does the arrangement of polar bonds in a molecule determine?

Answer 42

Whether or not the molecule will have an overall dipole.

Question 43

In what instance do polar molecules cancel out?

Answer 43

When the polar bonds are symmetrical - overall no dipole so non-polar.

Question 44

Example of cancelling out dipoles?

Answer 44

CO2

Question 45

In what case does the molecule have an overall dipole?

Answer 45

If the polar bonds are arranged unevenly across the whole molecule.

Question 46

Example of overall polar molecule?

Answer 46

H2O - negative charge is positioned more towards the oxygen atom.

Question 47

When is a substance purely covalent?

Answer 47

Diatomic gases because the electronegativity difference is 0 and so the bonding electrons are arranged completely evenly within the bond.

Question 48

How can you use electronegativity to predict the type of bonding?

Answer 48

The higher the difference in electronegativity, the more ionic in character the bonding becomes.

Question 49

What are intermolecular forces?

Answer 49

Forces between molecules.

Question 50

What is the strength of intermolecular forces?

Answer 50

They're much weaker than covalent, ionic or metallic bonds.

Question 51

What are the three types of intermolecular forces?

Answer 51

- London forces. - Permanet dipole-dipole interactions. - Hydrogen bonding

Question 52

What is the strongest intermolecular force?

Answer 52

Hydrogen bonding

Question 53

How is a temporary dipole formed in a charge cloud?

Answer 53

These clouds are moving really quick. At any particular moment, the electrons in an atom are likely to be more to one side than the other. This causes a temporary dipole.

Question 54

What does a temporary dipole cause?

Answer 54

Another temporary dipole in the opposite direction on a neighboring atom.

Question 55

How is the overall affect that the atoms are attracted to one another?

Answer 55

Dipoles are being constantly created and destroyed all the time as electrons are constantly moving.

Question 56

What do stronger London forces mean?

Answer 56

Higher boiling points.

Question 57

Why do larger molecules have stronger London forces?

Answer 57

They have a larger electron cloud.

Question 58

What do molecules with a greater surface area have?

Answer 58

A stronger London force because they have a bigger exposed electron cloud.

Question 59

What do molecules with stronger London forces have and why?

Answer 59

Higher boiling points as more energy is required to break the intermolecular forces.

Question 60

What kind of intermolecular forces do polar molecules have?

Answer 60

Permanet dipole-dipole interactions.

Question 61

When does hydrogen bonding occur?

Answer 61

When hydrogen is covalently bonded to fluorine, nitrogen or oxygen.

Question 62

What do molecules have which have hydrogen bonding?

Answer 62

-OH or -NH groups.

Question 63

How does hydrogen bonding affect the properties of a substance?

Answer 63

They are soluble in water and their density and viscosity are also affected.

Question 64

How is ice less dense than water?

Answer 64

Ice has more hydrogen bonds than liquid water and since the hydrogen bonds are relatively long, this makes the ice less dense than water.

Question 65

What is the main factor that determines the boiling point of a substance?

Answer 65

The strength of the induced dipole-dipole unless it has hydrogen bonds.

Question 66

What else increases the strength of the induced dipole-dipole?

Answer 66

Number of electrons in the molecule.

Question 67

Why are polar molecules soluble in water?

Answer 67

Water is a polar molecule, so only tends to dissolve other polar substances. Compounds with hydrogen bonds can from hydrogen bonds with water molecules so will be soluble.

Question 68

Why don't simple covalent compounds conduct electricity?

Answer 68

Covalent substances are uncharged.

Question 69

Anomalous properties of water?

Answer 69

- Less dense when ice as there is an open lattice due to longer hydrogen bonds. - Higher melting/boiling points than expected as hydrogen bonds require a larger amount of energy to overcome.

Question 70

Metallic bonding?

Answer 70

The strong electrostatic attraction between positive ions and negatively charged delocalised electrons in a regular lattice.