Topic 2- Bonding, structure and properties of matter Flashcards
1
Q
what are ions
A
charged particles
2
Q
what can ions be
A
single atoms or groups of atoms
3
Q
when atoms lose or gain electron to form ions, what are they trying to do
A
form a full outer shell
4
Q
what happens when metals form ions
A
they lose electrons from their outer shell to form positive ions
5
Q
what happens when non metals form ions
A
they gain electrons into their outer shell to form negative ions
6
Q
if two electrons are lost the charge is…
A
2+
7
Q
if two electrons are gained the charge is…
A
2-
8
Q
which groups readily form ions
A
groups 1,2,6,7
9
Q
are groups 1 and 2 metals or non metals?
A
metals
10
Q
do metals (groups one and two) lose or gain electrons and what do they form?
A
lose electrons to form positive ions (cations)
11
Q
are groups 6 and 7 metals or non metals?
A
non metals
12
Q
elements in the same group have the same number of…
A
electrons on their outer shell
13
Q
explain what ions each group form
A
1 form 1+
2 form 2+
6 form 2-
7 form 1-
14
Q
so if a sodium atom (group one) forms an ion, what has happened?
A
its lost one electron to form a positive sodium ion (Na+)
15
Q
why do simple ions often have noble gas electronic structures
A
because noble gas electronic structures have a full shell of outer electrons which is a very stable structure
16
Q
name the three types of bonding
A
ionic,metallic, covalent
17
Q
what is ionic bonding
A
when a metal and non metal react together, the metal atom loses electrons to form a positive ion and teh non metal gains THESE electrons to form a negative ion. these oppositely chatged ions are STRONGLY ATTRACTED to one another by ELECTROSTATIC forces and this force is called ionic bond
18
Q
in an ionic bonding dot and cross diagram, what happens with the dots and crosses
A
the dots go on one element and crosses on another
19
Q
describe the structure of an ionic compound
A
giant ionic lattice
the ions form a closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions, in all directions in the lattice
20
Q
how can you represent an ionic lattice
A
ball and stick diagram
21
Q
What are ionic compounds boiling and melting points like and why
A
High because the strong bonds between the ions
22
Q
explain a solid ionic compound
A
ions are in place so compounds can’t conduct electricit
23
Q
explain ionic compound when it melts
A
ions are free to move and carry electric current
24
Q
Why do ionic compounds dissolve easily
A
because the Ions separate and are all free to move in solution, so theyll carry an electric current
25
what is covalent bonding between
compounds of nonmetals and nonmetal elements
26
what happens when elements bond together in covalent bonding
they share pairs of electrons to make covalent bond
27
What makes covalent bonds strong
positively charged nucleus of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bond is very strong
28
where do atoms share electrons
only in their outer shells (highest energy levels)
29
what does each single covalent bond provide
One extra shared electron for each atom
30
what are simple molecular substances
consist of molecules in which the atoms are joined by strong covalent bonds.
31
how many electrons does hydrogen need to complete its outer shell
2
32
give the properties of simple molecular substances
very strong covalent bonds in the atoms which means by contrast the attraction between these molecules are very weak
33
are the melting and boiling points high or low
low because the molecules are easily parted from each other, because you only have to break the weak intermolecular forces, not the covalent bonds
34
what are most molecular substances like at room temperature
gases or liquids
35
The bigger the molecules...
the strength of the intermolecular forces increases, so more energy is needed to break them and the melting and boiling points increase
36
don’t simple molecular substances conduct electricity
because they aren’t charged so there are no free electrons or irons
37
what are polymers
Long chains of repeating units, which form a long molecule
38
what all the atoms in a polymer joined by
strong covalent bonds
39
how do you draw a repeating unit, for polymers
```
(H H)
( | | )
-(C-C)-
( | | )
(H H) n
```
40
how do you find the molecular formula of a polymer?
write down the repeating unit in brackets and put an n outside e.g polyethene is (C2H4)n
41
why are most polymers solid at room temperature
because the intermolecular forces between polymer moecules are larger than between simple covalent molecules so more energy is needed to break them
42
why do polymers have lower boiling points than ionic or giant molecular compounds
the intermolecular forces are weaker than ionic or covalent bonds
43
what are the bonds like in giant covalent structures
strong
44
why do giant covalent structures have very high melting and boiling points
lots of energy is needed to break the covalent bonds between the atoms
45
why dont giant covalent structures conduct electricity
they dont contain charged particles
46
give the main examples of giant covalent structures
diamond, graphite (made from carbon atoms only) and silicon dioxide (silica)
47
Describe the giant covalent bond in diamond
each carbon atom forms four covalent bonds in a very rigid giant covalent structure, which is strong
the strong covalent bonds take lots of energy to break so diamond has a very high melting point
doesnt conduct electricity because it has no free electrons or ions
48
describe the giant covalent bond in graphite
each carbon atom forms three covalent bonds to create layers carbon atoms arranged in hexagons. These arent held together by covalent bonds so can slide over each other, making it soft and slippery- lubricating material.
high melting point, covalent bonds need loads of energy to break.
each carbon atom also has one delocalised electron, so conduct electricity and thermal energy
49
describe silicon dioxide
one giant structure of silicon and oxygen
50
What are allotropes
different structural forms of the same element in the same physical state
51
what is graphene
one layer of graphite- a sheet of carbon atoms joined together in hexagons
52
by being only one atom thick, what is graphene
a two dimensional compound
53
features of graphene
network of covalent bonds- strong
very light- can be added to composite matericals to improve their strength without adding much weight
contains delocalised electrons, like graphite, so conducts electricity- can be used in electronics
54
what are fullerenes
molecules of carbon, shaped like closed tubes or hollow balls
55
what are fullerenes made up of
carbon atoms, arranged in hexagons but can also contain pentagons or heptagons
56
what was the first fullerene to be discovered called
buckminsterfullerene
57
what can fullerenes be used for
to cage other molecules, to deliver drugs into the body
lubricants
58
why are fullerenes great industrial catalysts
they have a huge surface area, so individual catalyst molecules can be attached to them
59
what are nanotubes
tiny carbon cylinders formed by fullerenes
60
what can nanotubes do
conduct electricity and thermal energy
high tensile strength(dont break when stretched)
nanotechnology, strengthen materials without adding weight (ie tenis racket frames) and electronics
61
what does metallic bonding involve
delocalised electrons in outer shell of metal atoms
62
what sort of structure do metals consist of
giant
63
describe metallic bonding
There are strong forces of electrostatic attraction between the positive irons and the shared negative electrons
these forces of attraction hold the atoms together in a regular structure and are known as metalic bonding.
(very strong bonding)
64
name some structures held together by metallic bonding
metallic elements and alloys
65
what produces ALL the properties of metals
delocalised electrons
66
what state are most metals at room temp
solid
67
describe the forces between metal atoms and delocalised sea of electrons
strong, so need lots of energy to be broken-> metalic compounds have high melting and boiling points
68
why are metals good conductors of heat and electricity
delocalised electrons carry current through structure
69
why are most metals malleable
the layers of atoms can slide over each other
70
whats an alloy
a metal made by combining two or more metallic elements, especially to give greater strength or resistance to corrosion.
71
why are alloys harder than pure metals
because when another element is mixed with a pure matal, the new metal atoms will distort the layers of metal atoms, making it more difficult for them to slide over each other
72
name the three states of matter
solid liquid gas
73
what does the state of something depend on
how strong the forces of attraction are between the particles of the material
74
what does the strength of forces are in states depend on
material
temperature
the pressure
75
describe a solid
1) strong forces of attraction, holding them in a fixed position to form very regular lattice arrangement
2) particles dont move around, keep definite shape and volume
3) particles vibrate in positions- the hotter it becomes, the more they vibrate, causing a slight expansion
76
describe a liquid
1) weak forces of attraction between particles
2) randomly arranges and free to move past each other
3) stick together fairly closely when moving
4) definite volume, dont keep definite shape
5) flow to fill a container
6) constantly moving with random motion
7) hotter- faster movement of particles
8) expand slightly when heated
77
describe a gas
1) force of attraction is very weak
2) free to move, far apart
3) particles travel in straight lines
4) dont keep definite shape or volume
5) fill any container
6) move constantly, random motion, hotter= faster movement
7) gases expand when heated, or pressure increases
78
what does aqueous mean
dissolved in water
79
what do physical changes do to a substance
dont change the particles- just their arrangement or energy
80
solid to liquid?
melting
WHEN HEATED,ITS PARTICLES GAIN MORE ENERGY, WHICH MAKES THEM VIBRATE MORE, WHICH WEAKENS THE FORCES THAT HOLD THE SOLID TOGETHER.
AT MELTING POINT, PARTICLES HAVE ENOUGH ENERGY TO BREAK FREE FROM POSITIONS
81
liquid to gas?
boiling
PARTICLES GAIN ENERGY WHEN HEATED, PARTICLES MOVE FASTER, WHICH WEAKENS AND BREAKS THE BONDS HOLDING THE LIQUID TOGETHER.
AT BOILING POINT, PARTICLES HAVE ENOUGH ENERGY TO BREAK BONDS (EVAPORATING) AND LIQUID BECOMES A GAS
82
gas to liquid?
condensing
AS GAS COOLS, PARTICLES NO LONGER HAVE ENOUGH ENERGY TO OVERCOME THE FORCES OF ATTRACTION BETWEEN THEM.
BONDS FORM BETWEEN THE PARTICLES
AT BOILING POINT, SO MANY BONDS HAVE FORMED BETWEEN THE GAS PARTICLES, THAT THE GAS BECOMES A LIQUID
83
liquid to solid?
freezing
WHEN A LIQUID COOLS, THE PARTICLES HAVE LESS ENERGY, SO MOVE AROUND LESS
NOT ENOUGH ENERGY TO OVERCOME ATTRACTION BETWEEN PARTICLES SO MORE BONDS FORM BETWEEN THEM.
AT MELTING POINT, SO MANY BONDS HAVE FORMED BETWEEN THE PARTICLES THAT THEY'RE HELD IN PLACE. LIQUID BECOMES A SOLID
84
the stronger the forces...
the more energy is needed to break them, and so the higher the melting and boiling points of the substance
85
how can you predict the state of a substance
temp below melting point- solid
above boiling point- gas
between two points- liquid
86
name the three types of particles and their size
coarse- diameter between 2500nm and 10 000nm (dust)
fine- diameter between 100nm and 2500nm
nanoparticles- diameter between 1nm and 100nm (contain only a few atoms)
87
give the surface area to volume ratio equation
SA divided by volume
88
as particles decrease in size...
the size of their surface area increases in relation to their volume, so the Sa to volume ratio increases
89
as you decrease the size of any cube by a factor of ten...
the surface area to volume ratio will always increase by a factor of ten
90
describe a nano particle
have very high surface area to volume ratio, which means the surface area is very large compared to the volume
91
how much of a material will you need for a catalyst if its made up of nanoparticles
youll need less compared to a material made up of normal sized particles
92
give some uses of nano particles
high surface area to volume ratio- catalysts
absorbed more easily by the body- nanomedicine- deliver drugs to the cells that need them
some conduct electricity- electric circuits for computer chips
silver ones have antibacterial properties- can be added to polymer fibres and then used to make surgical masks and wound dressing. can also be added to deodorants
improve moisterisers without making them really oily and other cosmetics.
93
give one use and a potential risk of nanoparticles
used in suncreams, protecting skin from harmful UV rays
give better coverage
not clear if they might damage cells
when washed away, could damage environment
-> things are clearly labelled if contain nanoparticles
