Bonding and Structure

Question 1

Ionic bonding is:

Answer 1

The electrostatic attraction between oppositely charged ions.

Question 2

Definition of a Giant ionic lattice is:

Answer 2

A 3D structure of oppositely charged ions, held together by strong ionic bonds.

Question 3

Explain why ionic compounds have high melting and boiling points.

Answer 3

Strong electrostatic attraction between oppositely charged ions in ionic compounds which requires more energy to break the bonds.

Question 4

Explain why molten or dissolved ionic compounds are able to conduct electricity.

Answer 4

Ionic compounds can conduct electricity when molten or aqueous as ions are free to move but when solid, ions are in a fixed lattice and cannot move.

Question 5

Why are some ionic substances less soluble than others?

Answer 5

Ionic bonds too strong to be broken by water.

Question 6

Metallic bonding is:

Answer 6

Strong electrostatic attraction between positive metal ions and delocalised electrons.

Question 7

Delocalised electrons are:

Answer 7

The outer shell electrons from metals, no longer associated with any one atom.

Question 8

Why do metals have high melting and boiling points?

Answer 8

As there are strong bonds/attraction between positive metal ions and delocalised electrons.

Question 9

Why are metals good at electrical conductivity as solids and liquids:

Answer 9

Delocalised electrons are free to move.

Question 10

Are metals soluble or insoluble?

Answer 10

Metals are insoluble in water or organic solvents unless they under go a reaction with them.

Question 11

Covalent bonding is:

Answer 11

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

Question 12

A lone pair is:

Answer 12

Outer shell pair of electrons not involved in chemical bonding.

Question 13

Dative (co-ordinate) covalent bonds:

Answer 13

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

Question 14

Some covalent compounds do not obey the 8 electrons in the outer shell octet rule. Give two examples.

Answer 14

Boron trifluoride and sulphur hexachloride

Question 15

Average bond enthalpy is:

Answer 15

Energy required to break 1 mole of a specified type of bond in a gaseous molecule.

Question 16

Electron-pair repulsion theory is:

Answer 16

1. Shape of a molecule or ion is determined by electron pairs surrounding the central atom.
2. Electron pairs repel each other.
3. Push as far apart as possible.
4. Lone pairs repel more than bonding pairs.

Question 17

How do you explain shapes of molecules?

Answer 17

Electron pairs repel, lone pairs repel bonding pairs by more.

Question 18

What is the name of the shape and bonding angle of 2 electron pairs around a central atom?

Answer 18

The name of the shape is linear and the bond angle is 180 degrees.

Question 19

What is the name of the shape and bonding angle of 3 electron pairs around a central atom?

Answer 19

The name of the shape is trigonal planar and the bond angle is 120 degrees.

Question 20

What is the name of the shape and bonding angle of 4 electron pairs around a central atom?

Answer 20

The name of the shape is tetrahedral and the bond angle is 109.5 degrees.

Question 21

What is the name of the shape and bonding angle of 6 electron pairs around a central atom?

Answer 21

The name of the shape is octahedral and the bond angle is 90 degrees.

Question 22

What is the name of the shape and bonding angle of 3 bonding pairs and 1 lone pair?

Answer 22

The name of the shape is pyramidal and the bond angle is 107 degrees.

Question 23

What is the name of the shape and bonding angle of 2 bonding pairs and 2 lone pair?

Answer 23

The name of the shape is non-linear and the bond angle is 104.5 degrees.

Question 24

In order to find the shape of a molecule with multiple bonds, the multiple bond is treated as:

Answer 24

A single area of electrons / as a bonding region

Question 25

Electronegativity is:

Answer 25

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

Question 26

In symmetrical molecules:

Answer 26

Dipoles cancel out.

Question 27

An intermolecular force is an attractive force between neighbouring molecules. Three types of forces exist, they are:

Answer 27

Permanent dipole-dipole
London forces
Hydrogen bonds

Question 28

A permanent dipole is: (polar molecule)

Answer 28

A small charge difference that does not change across a bond, with positive and negative partial changes on the bonded atoms, the result of the bonded atoms having different electronegativities.

Question 29

Explain how induced dipole-dipole forces are formed.

Answer 29

1. Temporary dipole forms due to electron (e-)
   movement
2. Induces a dipole in a neighbouring molecule
3. Electrostatic attraction between partial negative on one molecule with partial positive on neighbouring molecule.

Question 30

What effects the strength of induced dipole-dipole interactions?

Answer 30

How electronegative each atom is

Question 31

Explain what is needed to form a hydrogen bond.

Answer 31

Electronegative element: O,N,F (or) that is bonded to H.
Has a lone pair.

Question 32

Explain why ice is less dense than water.

Answer 32

Ice has an open lattice with H-bonds holding water molecules apart. When ice melts, rigid H-bonds collapse, molecules move closer together.

Question 33

Explain why water has a higher than expected melting and boiling points.

Answer 33

To melt or boil water, energy is needed to overcome H-bonds and London forces. This takes more energy, higher boiling point and melting point than expected just from London forces.

Question 34

What is the strength of the intermolecular forces?

Answer 34

Hydrogen B is stronger than permanent dipole-dipole and permanent dipole-dipole is stronger than London forces.

Question 35

Simple molecular structures:

Answer 35

Are held together by strong covalent bonds.

Question 36

What forces exist between iodine molecules?

Answer 36

London forces

Question 37

Which forces do we overcome when iodine changes shape?

Answer 37

London forces

Question 38

Do simple molecular structures conduct electricity, explain your answer?

Answer 38

No, there are no charged particles that are free to move.

Question 39

Are polar and non-polar simple molecular compounds soluble? Why?

Answer 39

Simple non-polar molecules will dissolve in non-polar solvents. Non-polar molecules will not dissolve in water. Polar molecules will dissolve in polar solvents like water as there is an attraction between the dipoles.

Question 40

What are physical properties of giant covalent lattices?

Answer 40

High melting points and boiling points.

Question 41

Do simple molecules dissolve?

Answer 41

Some can and it is due to the polarity.

Question 42

What is the shape around a carbon atom and what are its physical properties? (Diamond)

Answer 42

The shape is tetrahedral and each carbon is bonded to 4 other carbons. It has a high melting and boiling point and is hard and non-conductive.

Question 43

What is the shape around a carbon atom and what are its physical properties? (Graphite)

Answer 43

The shape is trigonal planar and each carbon is attached to 3 others. It has layers and is quite soft. It is conductive and strong with a high melting point.

Question 44

What is the shape around a carbon atom and what are its physical properties? (Graphene)

Answer 44

The shape is trigonal planar and each carbon is attached to 3 others. It is a single layer and has delocalised electrons so is conductive. It is strong and has a high melting point.