Covalent bonds

Question 1

what do covalent bonds do?

Answer 1

covalent bonds atoms share electrons so they can complete their outer shell

Question 2

what do covalent bonds occur between?

Answer 2

covalent bonds only occur between non-metals

Question 3

what is it called when 2 atoms shair a pair of electrons?

Answer 3

a covalent bond

Question 4

how do you know how many covalent bonds will form?

Answer 4

the number of the electrons that the atom needs to gain to get a full outer shell is the number of covalent bonds the atom will form

Question 5

give some examples of molecules containing covalent bonds

Answer 5

H20 Cl2 O2 CO2 H2

Question 6

what are the two types of covalent structures?

Answer 6

giant covalent structure
simple molecular structure

Question 7

name some simple molecular structures

Answer 7

oxygen (O2) chlorine (Cl2) hydrogen (H2) nitrogen (N2) water (H20) methane (CH4) hydrogen chloride (HCl)

Question 8

name some giant molecular structures

Answer 8

diamond, graphite and silicon dioxide

Question 9

what are the properties of giant covalent structures?

Answer 9

high melting and boiling points
dont conduct electricity or heat (except graphite)
insoluble in water
have giant networks
usually no intermolecular forces

Question 10

what are the properties of simple molecular structures?

Answer 10

weak intermolecular structures
strong covalent bonds
low melting and boiling points
dont conduct electricity
soluble in water
small molecules

Question 11

why do giant covalent structures have high melting/boiling points?

Answer 11

because they have strong covalent bonds that have to be broken by a lot of energy

Question 12

why is chlorine a gas at room temperature?

Answer 12

because it is a simple molecular structure and has weak intermolecular forces so it does not take a lot of energy to break these forces

Question 13

what do simple covalent structures tend to be at room temp?

Answer 13

liquids or gases

Question 14

why dont covalent molecules conduct electricity?

Answer 14

there are no charged particles to carry the charge
(except in graphite)

Question 15

how can you represent covalent bonds on a diagrams

Answer 15

stick diagrams

dot and cross diagrams

Question 16

what is a negative about the stick diagram to show covalent bonding?

Answer 16

they dont show the 3D structure of the compound and dosen’t show the relative size of the atoms

Question 17

what is a negative about the dot and cross diagram?

Answer 17

it dosent show the relative size of the atoms

Question 18

what is a negative about the 3D diagram to show covalent bonding?

Answer 18

get confusing for larger molecules
don’t show where the electrons have come from

Question 19

what type of structures have covalent bonds?

Answer 19

polymers, simple molecular and giant covalent

Question 20

how do you write out a polymer?

Answer 20

draw the repeating unit in brackets
make sure the bonds reach outside the brackets
put an n outisde the brackets

Question 21

what are polymers?

Answer 21

long chains of repeating units

Question 22

why is more energy needed to break apart polymers than simple moleculars?

Answer 22

molecules are larger so the intermolecular forces are larger and takes more energy to break them so often solid at room temp

still weaker than covalent and ionic