bonding, structure and the properties of matter

Question 1

process from solid to gas and vice versa

Answer 1

sublimation

Question 2

difference between evaporation and boiling

Answer 2

evaporation - particles leave liquid from surface only

boiling - bubbles of gas form throughout liquid

Question 3

what is stronger, ionic bonds or bonds between simple molecules

Answer 3

ionic bonds

Question 4

2 limitations of the particle model

Answer 4

• particles mostly empty space

- not spherical

Question 5

how is an ionic bond formed

Answer 5

when a metal and a non-metal react with each other

Question 6

what is an ionic lattice

Answer 6

the regular arrangement of irons in an ionic substance

Question 7

how are ionic lattices held together

Answer 7

with strong electrostatic forces

Question 8

which direction do forces of attraction from ions act in

Answer 8

all directions

Question 9

why do ionic compounds have high boiling and melting points

Answer 9

because of their strong electrostatic forces of attraction

Question 10

what do strength of ionic bonds depend on

Answer 10

the charge of ions, higher charge will have stronger forces

Question 11

when can a substance conduct electricity

Answer 11

• if it contains charged particles such as ions

- can move place to place

Question 12

when can an ionic compound conduct electricity

Answer 12

• when it’s melted to form a liquid

- dissolved in liquid to form aqueous solution

Question 13

where does covalent bonding mostly occure

Answer 13

in non-metal elements

Question 14

what is a double and triple bond in covalent bonding

Answer 14

double - 2 shared pairs of electrons

triple - 3 shared pairs of electrons

Question 15

why do small molecular substances have low melting and boiling points

Answer 15

they have weak intermolecular forces in comparison to the covalent bonds in the molecules

Question 16

how to change strength of intermolecular forces

Answer 16

bigger the molecule, stronger the intermolecular force

Question 17

can covalent bonds conduct electricity

Answer 17

no

Question 18

what happens to covalent bonds when substances melt or boil

Answer 18

they don’t change

Question 19

what are melting and boiling points on giant covalent structures

Answer 19

very high, large amounts of energy needed to overcome strong covalent bonds

Question 20

can giant covalent structures conduct electricity

Answer 20

no except for graphite

Question 21

how is diamond structured

Answer 21

• each carbon atom joined to four others by strong covalent bonds
• repeating tetrahedal structure
• no free electrons

Question 22

how is graphite structured

Answer 22

• each carbon atom jointed to 3 others by strong covalent bonds
• carbon atoms form layers of hexagonal rings
• no bonds between layers
• one delocalised electron from each atom

Question 23

why is graphite good as a lubricant

Answer 23

it’s slippery as the forces between layers are weak so easily slip off

Question 24

why does graphite conduct electricity

Answer 24

has delocalised electrons that are free to move between layers

Question 25

properties of graphene

Answer 25

- very high melting point | - very strong

Question 26

uses of graphene

Answer 26

electronics because delocalised electrons can move freely

Question 27

what are fullerenes

Answer 27

molecules of carbon atoms with hollow shapes

Question 28

what is buckminsterfullerene

Answer 28

molecules made of 60 carbon atoms which are spherical

Question 29

why is buckminsterfullerene slippery

Answer 29

weak intermolecular forces between each molecule that need little energy to overcome, also has low melting point

Question 30

what is a nanotube

Answer 30

like a layer of graphene rolled into a cylinder

Question 31

properties of nanotubes

Answer 31

- strong in tension resist being stretched | - conduct electricity

Question 32

uses of nanotubes

Answer 32

nanotechnology and electronics

Question 33

what is a polymer

Answer 33

a large molecule formed by many smaller molecules known as monomers

Question 34

what are the intermolecular forces between polymer molecules

Answer 34

strong compared to forces between small molecules, high melting and boiling point solid at room temp

Question 35

what is metallic bonding

Answer 35

giant structure of metal atoms and delocalised electrons moving between them

Question 36

why are metals good conductors of thermal energy

Answer 36

delocalised electrons transfer their energy

Question 37

why do metals have high melting and boiling points

Answer 37

large amounts of energy are needed to overcome metalling bonds in melting and boiling

Question 38

what is an alloy

Answer 38

a mixture of two or more elements where at least one is a metal

Question 39

why are alloys formed

Answer 39

many pure metals are too soft so combining with another makes it harder

Question 40

why is an alloy stronger than a pure metal

Answer 40

atoms of different sizes, distort the layers of atoms, greater force required for layers to slide, alloy is harder and stronger

Question 41

what is nanoscience

Answer 41

study of structures between 1 and 100nm in size (nanoparticles)

Question 42

what is a substance made of nanoparticles called

Answer 42

nanoparticulate

Question 43

uses of nanoparticulates

Answer 43

zinc oxide is invisible when a nanoparticulate used in suncream, rather than white when in bulk

Question 44

why are nanoparticulates used as catalysts

Answer 44

they have a large surface area to volume ratio - more efficient - catalyse different reactions producing different products

Question 45

possible risks of nanoparticles

Answer 45

- small size makes it easy to breathe in - can catalyse harmful reactions in body - toxic substances can bind because of large SA:VOL ratio