[Part 2]- C3- Bonding and structure 🔗

Question 1

What is covalent bonding ?

Hint: share

Answer 1

• covalent bonding is when non-metal atoms, share one or more pairs of electrons.

Question 2

When drawing dot-and-cross diagrams, what is the rule to remember ?

Answer 2

• when drawing dot-and-cross diagrams, you need to remember: that you only need to show the outer shell of electrons.

Question 3

When drawing dot-and-cross diagrams, what simple molecules do you need to be able to draw ? [8]

Answer 3

• when drawing dot-and-cross diagrams, the simple molecules that you need to be able to draw are:
• hydrogen
• chlorine
• oxygen
• nitrogen
• methane
• water
• hydrogen chloride
• ammonia

Question 4

When drawing a covalent bond of chlorine, how many covalent bonds will be formed and how many electrons does each chlorine atom have ?

Answer 4

• when drawing a covalent bond of chlorine, one covalent bond will be formed
• and each chlorine atom will have seven electrons

Question 5

When drawing a covalent bond of oxygen, how many covalent bonds will be formed and how many electrons does each oxygen atom have ?

Answer 5

• when drawing a covalent bond of oxygen, only one covalent bond will be formed
• and each oxygen atom will share six electrons

Question 6

When drawing a covalent bond of hydrogen, how many covalent bonds will be formed and how many electrons does each hydrogen atom have ?

Answer 6

• when drawing a covalent bond of hydrogen, only one covalent bond will be formed
• and each hydrogen atom will have one electron.

Question 7

When drawing a covalent bond of nitrogen, how many covalent bonds will be formed and how many electrons does each nitrogen atom have ?

Answer 7

• when drawing a covalent bond of nitrogen three covalent bonds will be formed
• and each nitrogen atom will have five electrons.

Question 8

When drawing a covalent bond of carbon, how many covalent bonds will be formed ?

Hint: not three

Answer 8

• when drawing a covalent bond of carbon, four covalent bonds will be formed

Question 9

When drawing a covalent bond of methane, how many covalent bonds will be formed and how many electrons does each methane atom share ?

Answer 9

• when drawing a covalent bond of methane, four covalent bonds will be formed
• and each hydrogen atom will share one electron, with chlorine [which has four electrons]

Question 10

When drawing a covalent bond of water, how many covalent bonds will be formed and how many electrons does each hydrogen atom share ?

Answer 10

• when drawing a covalent bond of water, two single covalent bond will be formed
• and two hydrogen atom will share one electron with oxygen [which has six electrons]

Question 11

When drawing a covalent bond of hydrogen chloride, how many covalent bonds will be formed and how many electrons does each hydrogen atom share ?

Answer 11

• when drawing a covalent bond of hydrogen chloride, only one covalent bond will be formed
• and each hydrogen atom will share one electron.

Question 12

When drawing a covalent bond of ammonia, how many covalent bonds will be formed and how many electrons does each ammonia atom share ?

Answer 12

• when drawing a covalent bond of ammonia , a single covalent bond will be formed
• and three hydrogen atoms will share one electron, with nitrogen [which has five electrons]

Question 13

What are the properties of small covalent molecules ?

Hint: melting and boiling

Answer 13

• small covalent molecules have low melting and boiling points.
• This is because simple moleces, have weak intermolecular forces between the molecules which don’t require a lot to energy to break [so little energy is needed to overcome the intermolecular forces]
• They are usually gases or liquids at room temperature, since they all boil at temperature below room temperature.
• [the larger the molecule, the stronger the intermolecular forces, therefore the higher the melting and boiling points will be.]

Question 14

What are some of the other properties of small covalent molecules ?

Hint: ⚡️

Answer 14

• small covalent molecules don’t conduct electricity. This is because the molecules don’t have an overall electrical charge.

Question 15

What can you tell me about the properties of giant covalent molecules ?

Hint: room temperature

Answer 15

• giant covalent molecules are always solids at room temperature, since they have millions of strong covalent bonds.
• Therefore, they will always have high melting and boiling points.
• [in order to melt these compounds, all the covalent bonds have to broken and this requires a great deal of energy. ]

Question 16

What element is diamond formed from ?

Answer 16

• diamond is formed from the element carbon.

Question 17

What are the properties of diamond ?

Answer 17

• diamond has a high melting point.
• this is because, each carbon atom forms four strong covalent bonds, therefore diamond has a huge number of covalent bonds and these have to be broken when diamond is melted.
• and because this requires a great deal of energy, this means that diamond is hard and has a high melting point.

Question 18

What are the other properties of diamond ?

Hint: why ?

Answer 18

• diamond can’t conduct electricity, because there are no free electrons to carry an electrical charge, and move throughout the whole structure- since each carbon atoms forms for covalent bonds

Question 19

What is the structure of silicon dioxide ?

Hint: bond

Answer 19

• silicon dioxide contains the elements oxygen and silicon [they are covalently bonded together.]
• each silicon, is bonded to three oxygens.

Question 20

What are the properties of silicon dioxide?

Hint: high

Answer 20

• silicon dioxide has a very high melting point because, a huge number of strong covalent bonds must be broken and this takes a great deal of energy.
• silicon dioxide also can’t conduct electricity because, it has no spare delocalised electrons to carry the charge [throughout the structure], as all electrons are used for bonding.

Question 21

What are the properties of graphite ?

Answer 21

• graphite has a high melting and boiling point because, it has many strong covalent bonds which require a great deal of energy to break.
• graphite is also slippery because, the hexagonal rings in layers, have no covalent bonds between the layers, therefore they can slide over each other, since the intermolecular forces between them are weak.

Question 22

What are some other properties of graphite ?

Hint: ♨️, ⚡️

Answer 22

• As each carbon atom forms three covalent bonds to three other carbon atoms, this means each carbon atom has a single electron in its outer energy level, which isn’t in a covalent bond.
• These electrons are released from the carbon atom and are known as delocalised electrons.
• the delocalised electrons, can then carry the electrical charge throughout the whole structure= so it can conduct electricity
• ; graphite can also conduct heat because the delocalised electron, can move throughout the whole structure and tranfer thermal energy carry

Question 23

What is the structure of graphite ?

Answer 23

• graphite only contains carbon atoms, and each carbon atom forms three covalent bonds to three other carbon atoms. [since graphite is based on the element carbon, it’s not a metal]

Question 24

What is graphite a good conductor of ?

Answer 24

• graphite is a good conductor of heat and electricity.
• In this prospect, it’s similar to metals as both graphite and metals have delocalised electrons that can move throughout the whole structure.