Chap 4 Chemical Bonding

Question 1

What are the horizontal and vertical rows of the periodic table called?

Answer 1

The horizontal rows of the periodic table are called periods while the vertical rows of the periodic table are called groups

Question 2

What is noble gas configuration?

Answer 2

An atom achieves noble gas configuration when their outermost shell (valence shell) is completely filled and is when it is most stable. Other elements will try to obtain the same electronic configuration as a noble gas by either gaining or losing electrons to form ions.

Question 3

What are metals defined as?

Answer 3

Metals are defined as atoms which have the tendency to give away electrons in order to achieve noble gas configuration as it has either very few electrons on its valence shell, or its valence shell is very far away from the nucleus.

Question 4

What are non-metals defined as?

Answer 4

Non-metals are defined as atoms which have a tendency to take in electrons in order to achieve noble gas configuration.

Question 5

What is ionic bonding?

Answer 5

Ionic bonding is defined as the transfer of electrons from a metallic atom to a non-metallic atom, in order to achieve noble gas configuration.

Question 6

What is covalent bonding?

Answer 6

Covalent bonding is defined as the sharing of electrons between two or more non-metallic atoms, in order to achieve noble gas configuration.

Question 7

Describe the structure of a giant ionic lattice

Answer 7

Positive and negative ions held together by strong electrostatic forces of attraction, forming a giant ionic lattice.

Question 8

Describe the melting and boiling point of an giant ionic lattice structure

Answer 8

A giant ionic lattice structure has high melting and boiling points, as a large amount of energy is required to overcome the strong electrostatic forces between the particles.

Question 9

What is the solubility of an giant ionic lattice

Answer 9

Generally soluble in water, but there are many exceptions that remain insoluble e.g. silver chloride.

Question 10

Describe the electrical conductivity of an giant ionic lattice

Answer 10

A giant ionic lattice has poor electrical conductivity in solid state as the ions are held in fixed positions. A giant ionic lattice has good electrical conductivity in liquid or aqueous state, due to the presence of mobile ions which allow the flow of electricity.

Question 11

Describe the structure of a simple molecular structure

Answer 11

Small molecules loosely held together by weak inter molecular forces of attraction.

Question 12

Describe the melting and boiling point of a simple molecular structure

Answer 12

Low melting and boiling points, as a small amount of energy is required to overcome the weak intermolecular forces between the particles.

Question 13

What is the solubility of a simple molecular structures?

Answer 13

Generally insoluble in water (except NH3, Cl2)

Question 14

Describe the electrical conductivity of a simple molecular structure

Answer 14

Poor electrical conductivity in all states, due to the absence of mobile ions and electrons.

Question 15

Describe the structure of a metallic lattice structure

Answer 15

Positive ions and seas of delocalize electrons are held by strong electrostatic forces of attraction.

Question 16

Describe the melting and boiling point of a metallic lattice structure

Answer 16

Metallic structures have a moderate to high melting and boiling point as the strong electrostatic forces of attraction need a lot of energy to overcome.

Question 17

What is the solubility of a metallic lattice structure

Answer 17

Insoluble in water.

Question 18

Describe the electrical conductivity of a metallic lattice structure.

Answer 18

Metallic structures have good electrical conductivity in both solid and liquid states as it has a sea of delocalised electrons.

Question 19

Describe the structure of a giant molecular structure.

Answer 19

Giant molecular structures have many covalently bonded atoms.

Question 20

Describe the melting and boiling point of a giant molecular structure

Answer 20

High melting and boiling point as the strong covalent bonds require a lot of energy to break.

Question 21

What is the solubility of a giant molecular structure

Answer 21

Insoluble in water (too big)

Question 22

Describe the electrical conductivity of a giant molecular structure

Answer 22

Poor electrical conductivity (except graphite due to the presence of mobile electrons)

Question 23

Describe two factors affecting the strength of the electro static forces in giant ionic structures

Answer 23

The larger the magnitude of charge on the ions, the greater the electrostatic forces of attraction. The larger the physical size of the ions, the weaker the electrostatic forces of attraction.

Question 24

How does the size of a simple molecular structure affect the intermolecular forces?

Answer 24

The larger the molecule size, the stronger the intermolecular forces.

Question 25

Define a metallic structure

Answer 25

A metallic structure is defined as a lattice of positive ions within a 'sea' of delocalised electrons

Question 26

What is a mixture of metal called?

Answer 26

An alloy

Question 27

Aluminium and sodium are both in the third period of the periodic table. Suggest why the melting point of pure aluminium metal is significantly higher than the melting point of pure sodium metal. (Aluminium has 3 valence electrons and sodium has 1 )

Answer 27

Aluminium has three valence electrons per atom while sodium has one valence electron per atom. Hence each aluminium atom delocalized three electrons in its metallic lattice, compared to sodium which only delocalized one electron per atom. More energy is needed to overcome the stronger electrostatic forces of attraction in the aluminium metallic lattice.

Question 28

Suggest why metals are able to conduct electricity even in solid state.

Answer 28

Due to the presence of delocalized electrons, which are free to move.

Question 29

Explain, in terms of conducting particles, how does the conduction of electricity in a molten ionic compound differs from the conduction of electricity in a metal.

Answer 29

A molten ionic compound conducts electricity through the flow of mobile ions, while a metal conducts electricity through the flow of mobile electrons to carry electric charges.

Question 30

Briefly describe how the types of bonding differ in giant molecular structures and simple molecular structures.

Answer 30

A macromolecule consists of atoms entirely bonded together by covalent bonds, whereas a simple molecular substance has both covalent bonds and intermolecular forces of attraction.

Question 31

Do you expect macromolecules to be able to conduct electricity? Why?

Answer 31

No, there are no mobile ions or electrons.

Question 32

Do you expect macromolecules to have a high or low melting point? Why?

Answer 32

High melting point - a large amount of energy will be required to break the strong covalent bonds between the atoms.

Question 33

Why is graphite considered a special macromolecule?

Answer 33

Each carbon atom in graphite only form three bonds. Hence, the last unbonded valence electron is then delocalised. This results in layers of carbon atoms covalently bonded into a hexagonal arrangement and between each layer are weak intermolecular forces. This means that graphite has a soft and slippery texture as the weak intermolecular forces allow the layers of carbon atoms to slide over each other easily and has good electrical conductivity as there are delocalised electrons present which are mobile and can hence carry an electric current.

Question 34

Graphite is similar to diamond in some ways. State two similarities between the structure of diamond and graphite.

Answer 34

Both are macromolecules/contain covalent bonds. Both consist entirely of carbon atoms/ are allotropes of carbon.

Question 35

State two differences between the physical properties of diamond and graphite.

Answer 35

Diamond is hard and strong, while graphite is soft and slippery. Diamond is unable to conduct electricity, while graphite is able to.

Question 36

What similarities do elements in the same period share?

Answer 36

They have the same number of electron shells

Question 37

What similarities do elements in the same group share?

Answer 37

They have the same number of valence electrons.

Question 38

Explain why aluminium oxide is unable to conduct electricity when it is a solid but can conduct electricity when molten. ( It is an Ionic compound)

Answer 38

Aluminium oxide is an ionic compound. When solid, its ions are held in fixed positions and hence are unable to carry a current. However, when molten, the ions are able to move and hence able to carry an electric current.

Question 39

What is one factor that affects the strength of forces of attraction in a metallic lattice structure?

Answer 39

Number of valence electrons delocalised into the metallic lattice. (More delocalised electrons, stronger electrostatic forces of attraction)

Question 40

What is the structure of silicon dioxide?

Answer 40

Giant molecular structure.

Question 41

What is the structure of silicon?

Answer 41

Giant molecular structure.