Covalent bonding and giant structures

Question 1

What is covalent bonding?

Answer 1

a shared pair of electrons between atoms

Question 2

Why are covalent bonds strong?

Answer 2

a lot of energy is needed to break them because both nuclei are strongly attracted to the shared pair of electrons in the covalent bond

Question 3

Covalent bonds occur in…

Answer 3

non- metallic elements

compounds of non-metals

Question 4

What are simple molecules?

Answer 4

a relatively small number of non-metal atoms joined together by covalent bonds

Question 5

why can’t simple molecules conduct electricity?

Answer 5

have no overall charge , or charged particles that can separate

Question 6

why do substances that consist of simple molecules have a low melting and boiling points?

Answer 6

because they have weak intermolecular forces which are easily overcomed

Question 7

what are intermolecular forces?

Answer 7

forces of attraction between the molecules

Question 8

intermolecular forces are weaker than

Answer 8

covalent bonds

Question 9

the larger the molecules are the ____ the intermolecular forces between the molecules become

Answer 9

stronger

Question 10

larger molecules have a _______ melting and boiling point

Answer 10

higher

Question 11

Why does the melting and boiling points increase as you go down Group 7

Answer 11

because the molecules get larger so the intermolecular forces are stronger

Question 12

Why do giant covalent bonds have high melting and boiling points?

Answer 12

because their strong covalent bonds must be overcome before they can melt or boil

Question 13

Diamond and graphite are forms of what?

Answer 13

carbon

Question 14

How many strong covalent bonds does each carbon atom make with other carbon atoms in diamonds?

Answer 14

4

Question 15

What are the features of a diamond? (3)

Answer 15

• It has a giant, rigid covalent lattice
• All the strong covalent bonds mean that it is a very hard substance with a very high melting point
• there are no charged particles, so it does not conduct electricity

Question 16

How many covalent bonds does each carbon atom form with other carbons in graphite?

Answer 16

3

Question 17

What are the features of graphite?

Answer 17

• has a giant covalent structure and a very high melting point
• has layered, hexagonal structure
• layers are held together by weak intermolecular forces so the layers can slide past each other, making graphite soft and slippery
• one electron from each carbon atom is delocalised = allows graphite to conduct heat and electricity

Question 18

Why is graphite soft and slippery?

Answer 18

because the layers are held together by weak intermolecular forces so the layers can slide past each other,

Question 19

Silicon dioxide has a lattice structure similar to what giant covalent structure?

Answer 19

diamond

Question 20

what are the features of silicon dioxide?

Answer 20

• each oxygen atom is joined to 2 silicon atoms

- each silicon atom is joined to 4 oxygen atoms