bonding

Question 1

what is ionic bonding?

Answer 1

non metal + metal

Question 2

what holds ionic bonds together?

Answer 2

electrostatic forces of attraction between oppositely charged ions (positive metal cations and negative non-metal anions)

Question 3

what is an ion?

Answer 3

positively charged (missing electrons) or negatively charged (has extra electrons) atoms/groups of atoms

Question 4

how do ionic compounds bond?

Answer 4

electrons trasfered so both ions have full outer shells

Question 5

properties of ionic compounds (4)

Answer 5

• very high melting and boiling points
• hard but brittle
• soluable in water
• conduct electricity as liquids (ie disolved) but not as solids

Question 6

why do ionic compounds have very high melting and boiling points ?

Answer 6

strong electrostatic forces of attraction between oppositely charged ions throughout the giant structure require lots of energy to overcome

Question 7

why are ionic compounds hard but brittle?

Answer 7

when layers slide, ions with the same charge repel each other, breaking up the giant lattice structure

Question 8

what structure are ionic compounds?

Answer 8

giant lattice, meaning one ion of x is completly surrouded by oppositely charged ions of y

Question 9

why are ionic compounds soluable in water?

Answer 9

water is a polar molecule so the oppositely charged ions are attracted and therefore split up by the water, breaking up the lattice

Question 10

why are ionic compounds not able to conduct electricity as solids?

Answer 10

ions are held in a fixed position so not able to carry a charge (conduct electricity)

Question 11

why are ionic compounds able to conduct electricity when molten/disolved ?

Answer 11

ions are free to move so can carry a charge

Question 12

why does MgO have a higher melting point than NaCl?

Answer 12

MgO has a double charge meaning 2 electrons are transferred (Mg2+, O2-) so the electrostatic force of attractio is much stronger than the single bond in NaCl (Na+, Cl-)

Question 13

what does -ide mean?

Answer 13

negative ion eg chloride is Cl-

Question 14

what does -ate mean?

Answer 14

negative ion, oxygen also present
eg SO4 2- is sulfate and oxygen

Question 15

what are covalent bonds?

Answer 15

non metal + non metal (both need to gain electrons so share one or more pairs)
electrostatic attraction betwee the positvely charged protons in the nucleus and the negative shared pair of electrons

Question 16

what is the structure of simple covalent substances?

Answer 16

strog covalent bonds between atoms in a molecule BUT weak intermolecular forces between neighbouring molecules

Question 17

size of molecules

Answer 17

very small (only slightly larger than atoms), 10^-10 m

Question 18

why do simple covalent compounds have low melting and boiling points?

Answer 18

weak intermolecular forces betwee molecules do not need lots of energy to overcome

Question 19

why are simple covalent compounds not able to conduct electricity?

Answer 19

no ions or electrons free to move

Question 20

why are simple covalent molecules insoluable?

Answer 20

water is polar but molecules are not charged so it is in not able to split them i

Question 21

what is the structure in metallic bonding?

Answer 21

positive metal cations held together by a sea of delocalized electrons in layers due to a strong electrostatic force of attraction

Question 22

properties of metals (4)

Answer 22

• ductile ad malleable
• high melting and boiling points
• good conductors of electricity
• good conductors of heat

Question 23

properties of simple covalent molecules (3)

Answer 23

• very low melting and boiling points
• don’t conduct electricity
• insoluable

Question 24

why are metals ductile and malleable?

Answer 24

layers are able to move across each other since movement of sea of delocalized electrons holds whole structure together

Question 25

why do metals have high melting and boiling points?

Answer 25

lots of strong electrostatic attraction in a giant metallic lattice so lots of energy needed to overcome

Question 26

why are metals good conducturs of electricity?

Answer 26

delocalized electrons can move and carry a charge

Question 27

why are metals good conducturs of heat?

Answer 27

- delocalized sea of electrons can move - when heated, move more due to increase in kinnetic energy so transfer the energy (and heat) to other electrons

Question 28

key words - ionic bonding

Answer 28

- strong electrostatic forces of attraction between oppositely charged ions - giant lattice - transfer of electrons

Question 29

key words - metallic bonding

Answer 29

- delocalized sea of electrons - layers - giant lattice structure - positive metal cations

Question 30

key words - simple covalent bonding

Answer 30

- strong covalent bonds between atoms - weak intermolecular bonds between molecules

Question 31

what is the structure of giant covalent substances?

Answer 31

giant lattice

Question 32

what is the difference between simple and giant covalent substances?

Answer 32

in simple covalent substaces there are weak intermolecular bonds between molecules whilst in giant covalent there are no weak intermolecular bonds, only strong covalent bonds between atoms

Question 33

what are diamonds and graphite examples of?

Answer 33

- giant covalet substances - both forms of carbon

Question 34

why are diamond and graphite different?

Answer 34

diamond - one carbon bonded to 4 others in a tetrahedral structure graphite - one carbon bonded to 3 others in layers

Question 35

what are the melting points of diamonds and graphite and why?

Answer 35

- very high because there are lots of strong covalent bonds throughout the giant structure to be overcome

Question 36

why are diamonds hard?

Answer 36

strong covalent bonds throughout giant structure require lots of energy to overcome

Question 37

why is graphite soft?

Answer 37

soft due to weak intermolecular forces between the layers , meaning layers can slide easily

Question 38

conductability of diamond and why

Answer 38

- cannot conduct electricity - no delocalized electrons since all electrons are being shared in covalet bonds/ fixed structure

Question 39

conductability of graphite and why

Answer 39

very good conductor due to delocalized electrons between layers (which can break free from the weak intermolecular forces) which can move freely

Question 40

uses of diamonds and why

Answer 40

- industrial drill bits (hardness) - jewlery shine

Question 41

uses of graphite and why

Answer 41

- pencil lead and industrial lubricators > layers can easily slide + soft - electrodes > good electrical conductivity

Question 42

what are fullerenes and how can they be used?

Answer 42

- SIMPLE covalent substances - hollow molcules of carbon shaped like tubes or balls (eg C60 - buckministerfullerene) aranged into hexagons/pentagons/heptagon rings - can be used as carbon nanotubes (often base for catalysts due to large surface area)

Question 43

what is graphene amd how can it be used?

Answer 43

- single sheet of carbon atoms bonded together in hexagons - one atom thick so can strengthen composite materials without adding to weight

Question 44

what are polymers and their uses ?

Answer 44

- long chain-like molecules covalently bonded - strong covalent bonds (all are solid at room temp) but weak intermolecular forces - eg polyethene which has very weak intermolecular forces making it flexibke and ideal for plastic bags

Question 45

# identifying type of substance what type of substance is it if it has high bpt ad mpt?

Answer 45

not simple molecular (giant, ionic or metal)

Question 46

# identifying type of substance what type of substance is it if it has low mpt ad bpt, bad conductor in all states?

Answer 46

simple covalent

Question 47

# identifying type of substance what type of substance is it if it can conduct when solid?

Answer 47

metal

Question 48

# identifying type of substance what type of substance is it if it has high mpt and bpt, poor conductivity (1 exception) ?

Answer 48

giant covalent apart from graphite which is a good conductor of electricity

Question 49

# identifying type of substance what type of substance is it if it has high mpt and bpt, can conduct as a liquid/aqueous but not as a solid?

Answer 49

ionic