covalent bonding

Question 1

Covalent compounds are formed when

Answer 1

pairs of electrons are shared between atoms

Question 2

only __________ elements participate in covalent bonding

Answer 2

non metal

Question 3

just like un ionic bonds, each atom has a ___ outer shell of electrons

Answer 3

full

Question 4

Covalently bonded substances may consist of __ molecules or ___ molecules

Answer 4

small
giant

Question 5

a single covalent bond is

Answer 5

when two adjacent atoms share one pair of electrons

( like hydrogen)( H-H)

Question 6

If two adjacent atoms share two pairs of electrons, two covalent bonds are formed, also known as a

Answer 6

Double bond

Question 7

Some atoms need to share more than one pair of electrons to gain a full outer shell of electrons

true or false

Answer 7

true

Question 8

Properties of simple molecular compounds

Answer 8

They have low melting and boiling points so covalent compounds are usually liquids or gases at room temperature

As the molecules increase in size, the melting and boiling points generally increase

Small molecules have poor electrical conductivity

Question 9

They have low melting and boiling points as there are

Answer 9

only weak intermolecular forces acting between the molecules

Question 10

why are they gases or liquids at room temp

Answer 10

the forces are very weak when compared to the covalent bonds

Question 11

why does melting point increase, when size increase

Answer 11

As the molecules increase in size the intermolecular forces also increase as there are more electrons available

This causes the melting and boiling points to increase

Question 12

why are they poor conductors

Answer 12

there are no free ions or electrons to carry the charge.

Question 13

are covalent compounds conductors or insulators

Answer 13

insulators

Question 14

simple molecular structures have low melting & boiling points bevause

Answer 14

There are weak intermolecular forces between the molecules

These forces require little energy to overcome

Question 15

Most simple molecular structures are either ____ or ___ at room temperature

Answer 15

gases or liquids

Question 16

giant covalent structures are ___ with ___ melting and boiling points

Answer 16

solids
high

Question 17

they have a ___ _____ structure

Answer 17

giant lattice

Question 18

All giant covalent structures have high melting points because:

Answer 18

There are strong covalent bonds between atoms

These require lots of energy to overcome

Question 19

diamond and graphite contain only ____ atoms

Answer 19

carbon

Question 20

in diamond, each carbon atom bonds with ___ other carbons forming a ___-

Answer 20

4
tetrahedron

Question 21

diamond is very hard because : (3)

Answer 21

Each carbon atom is covalently bonded to four other carbon atoms

The covalent bonds are very strong

The hardness of diamond makes it useful for cutting tools

Question 22

diamond has a high melting point because (2):

Answer 22

It has a giant covalent structure

There are strong covalent bonds between atoms which need lots of energy to break

Question 23

in graphite, each carbon atom is bonded to __ others

Answer 23

3

Question 24

in graphite there are ___ electrons

Answer 24

free, delocalised

Question 25

properties of graphite (4)

Answer 25

soft
slippery
high melting point
conduct electricity and heat (electrons can move between the layers in graphite)

Question 26

why can graphite conduct electricity and heat

Answer 26

because there are delocalised electrons as carbon atoms only form 3 bonds, the delocalised electrons are free to move

Question 27

why does graphite have a high melting and boiling point

Answer 27

this is because each carbon atom forms 3 other strong bonds which need a lot of energy to break.
Because it has a giant covalent structure