Topic 2- Bonding, Structure and Properties of Matter Flashcards
1
Q
what elements do covalent bonding
A
2 non metals
2
Q
what does bonding mean
A
atoms share electrons with each other to get full outer shells
3
Q
what is a covalent bond
A
a shared pair of electrons between non metal atoms
4
Q
how many covalent bonds does nitrogen need to make with hydrogen
A
3
NH3
it needs 3 covalent bonds to make up the extra 3 electrons needed (2.5)
5
Q
how do you draw a displayed formula for NH3
A
H
(
H - N - H
the lines represent the covalent bond
6
Q
what is it called when an element has 3 pairs of covalent bonds between another element(eg N2)
A
a triple bond
7
Q
what is a simple molecular substance
A
substance made up of a few atoms of non metals joined by covalent bonds
8
Q
what are the properties of simple molecular substances
A
- usually have simple molecular structures
- very low melting and boiling points
- most are gas or liquid at room temperature
- don’t conduct electricity
9
Q
why do the simple molecular substances have very low melting and boiling points
A
weak intermolecular forces
10
Q
why the simple molecular substances not conduct electricity
A
there are no free electrons to carry charge
11
Q
what happens as simple molecular structures get bigger
A
as the molecules get bigger, the strengths of the IMFs increase, so melting and boiling points increase
12
Q
what can be used to show bonding
A
- dot and cross diagrams
- displayed formula
13
Q
what does a dot and cross diagram show
A
show the arrangement of electrons in an atom or ion
- they can show which atom of the electron in an ion originally came from
14
Q
what are the four state symbols
what do they mean
A
(s) solid
(L) liquid
(G) gas
(Aq) aqueous
15
Q
what does aqueous mean
A
dissolved in water
16
Q
ESQ ethanol melts at
-114 C and boils at 78 C. Predict the state at
a) -150 C
b) 0 C
c) 25C
d) 100 C
A
a)solid
b)liquid
c)liquid
d)gas
17
Q
how do gases move
A
move constantly with random motion
18
Q
what is the force like between the gas particles
A
very weak
19
Q
what happens when the particles in a gas get hotter
A
the hotter they get the more they move- so expand or increase in pressure
20
Q
how do the particles in a gas move
A
free to move, far apart and move in straight lines
21
Q
do gases fill the container
A
always- don’t keep a definite shape or volume
22
Q
how doe a solid become liquid
A
melting
23
Q
how does a liquid become a solid
A
freezing
24
Q
how does a gas become a liquid
A
condensing
25
how does a liquid become a gas
boiling
26
how does a solid become a gas
sublimation
27
what happens as the forces become stronger
more energy is needed to break them
28
how are the particles in a solid arranged
- regular arrangement, vibrate in fixed positions
29
what happens as solids become hotter
they vibrate more and expand slightly
30
what are the forces like in a solid
strong forces of attraction and hold them close in fixed positions
31
do they keep a definite shape and volume
yes
32
what happens when a liquid gets hotter
they get faster and they move- expand slightly
33
how does a liquid move
constantly moving randomly, free to move past each other
34
how is a liquid arranged
tend to stick close together, constantly changing shape
35
what are the forces between particles in a liquid
weak forces so free to move
36
do liquids have a definite volume and/or shape
volume- yes
shape- no
37
do liquids flow to fill the container
yes
38
how many covalent bonds does each carbon atom in diamond make
each atom makes 4 atoms
39
what is diamond made out of
carbon
40
why is diamond very hard
because each carbon atom makes 4 covalent bonds
41
what are the properties of diamond
- very high melting point
- doesn't conduct electricity
42
why does diamond have a very high melting point
because it needs lots of energy to break the 4 covalent bonds
43
why does diamond not conduct electricity
it has no free electrons or ions to carry the charge
44
what is graphite made of
carbon
45
what are the structures of carbon
- fullerenes
- diamond
- graphene
- graphite
46
how many covalent bonds does graphite make
3
47
what does graphite's 3 covalent bonds create
create shells arranged in hexagons - layers
48
why are the layers free to move over each other
the layers are only held together by weak forces so free to move over each other- makes them soft and slippy
49
what are the properties of graphite
- high melting point
- conducts thermal energy and electricity
50
why does graphite have a high melting point
needs lots of energy to break
51
why does graphite conduct thermal energy and electricity
it has a free delocalised electron to carry charge through the whole structure
52
what is graphite ideally used for
used for lubricating material
53
what are fullerenes shaped like
shaped like closed tubes or hollow balls
54
what is an example of a fullerene
Buckminster fullerene
55
what are fullerenes made of
carbon
56
what can fullerenes be used for
- good lubricant
- good industrial catalyst
- can be used to deliver drugs into the body
57
what is good about fullerenes
they have a huge surface area
58
what is graphene
one layer of graphite , a sheet of carbon atoms joined together in hexagons
59
how big is graphene
one atom thick- 2D
60
what make graphene strong
the covalent bonds
61
what are the properties of graphene
- very light
- conduct electricity
62
because graphene is so light, what can it be used for
can be added to composite materials to improve their strengths without adding weight
63
why can graphene conduct electricity
it had delocalised electrons so conduct though the whole structure
64
what can fullerenes form
nanotubes( tiny carbon cylinders)
65
what is the ratio between the length and diameter of nanotubes
very high
66
what are the properties of nanotubes
- can conduct electricity and thermal energy
- high tensile strengths
67
what can nanotubes be used for
- in electronics
- strengthen material
68
what are the properties of giant covalent structures
- high melting and boiling points(lots of energy needed to break them)
- don't conduct electricity(don't contain charged particles)
69
how are the atoms in giant covalent structures bonded
bonded to each other by strong covalent bonds
70
what are examples of giant covalent structures
- diamond
- graphite
- silicon dioxide
71
what is sand made of
silicon dioxide- each grain of sand is one giant structure of silicon and oxygen
72
what are polymers
long chains of repeating units- joined by strong covalent bonds
73
how do you draw a polymer
draw the shortest repeating section called the repeating unit
74
what is an example of how a polymer is drawn
( H H )
( [ [ )
-( C C )-
( [ [ )
( H H) N
75
how do you find the molecular formula from a repeating unit
- write down the repeating unit formula
- add N
ex. (C2 H4) N
76
what does the N mean in the repeating unit
tells us that the unit repeats a lot of times
77
what are the properties of polymers
- solid at room temperatures
- have lower boiling points
78
why are polymers solid at room temperatures
the IMFs are larger than between simple covalent molecules, more energy is needed to break them
79
why do polymers have lower boiling points
the IMFs are still weaker that ionic or covalent bonds
80
what is an ionic compound
any compound that only contains ionic bonds
81
what is the structure of ionic compounds
called a giant ionic lattice
82
why do atoms lose or gain electrons
to try and get a full outer shell- form ions
83
what happens when a metal and a non metal react together
- the metal atom loses electrons to form positively charged ions
- the non metal gain these electrons to form a negatively charged ion
84
what are the oppositely charged ions strongly attracted to
by electrostatic forces, the attraction is called ionic bonding
85
what elements react together in ionic bonding
metal and non metal
86
when using nano particles in science what is in it known as
nanoscience
87
how are particles put into catogries
depending on diameter
88
what are the 3 types of particles
- coarse
- fine
- nano
89
what are the size of coarse particles
between 2500nm and 10000 nm
90
what are the size of fine particles
between 100nm and 2500nm
91
what are the size if nano particles
between 1nm and 100nm
92
do nanoparticles have a large surface area to volume ration
yes
93
what can affect the way a particle behaves
the surface area: volume
94
what happens as a particle decreases in size?
what can this cause?
- the size of their surface arear increases in relation to volume
- this can cause the properties of a material to be different depending on whether its a nanoparticle or whether its in bulk
95
what can nanoparticles be used for
- make new catalysts- huge sa:v
- nano medicine- tiny particles are absorbed easier by body
- some conduct electricity so can be used in circuits
-can be used in cosemetics
- silver nanoparticles have antibacterial properties(surgical masks etc)
96
what is the problem about nanoparticles on health
effects of nanoparticles on health aren't fully understood
- new products are tested thoroughly
- some people say we don't know the long term impacts on health, uses it too early and they should be clearly labelled
97
why are nanoparticles used in sun cream
better at protecting the skin but could damage cells if gets into the body or damage environment
98
what do the ions form in a compound
form a close regular lattice arrangement
99
what are the forces in ionic compounds
there are strong electrostatic forces of attraction between oppostiely charged ions in all directions
100
what are the properties of ionic compounds
- all have high melting and boiling points
- when solid, can conduct electricity
- when they melt, they carry charge
- some dissolve easily in water and carry electric charge
101
why can ionic compounds not conduct electricity when solid?
when liquid?
- the ions are held in place
- ions are free to move
102
why can ionic compounds carry charge when dissolved easily in water
ion separate and are free to move in solution
103
what is an empirical formula
eg. K 2O
104
how do you work out the empirical formula from a diagram
1) work out what ions are in the compound
2) work out what charges the ions will form
3)balance the charge so the empirical formula charge is 0
105
ESQ what's the empirical formula of the ionic compound
+ * + ** + *
* * + * +++
* is potassium ion
Group 1 (+1)
+ is oxide ion
Group 6 (2-)
we need 2 potassium ions to balance the oxide ion so...
K2 O
106
what elements are bonded in metallic bonding
metal and metal
107
what are the properties of metallic bonding
- solid at room temperature
- good conductors of electricity and heat
- most are malleable
108
what are the strong forces between in metallic bonding
strong electrostatic forces of attraction between positive metal ions and the shared negative electrons
109
what is an alloy
a mixture of two or more elements
110
what is good about alloys
they are harder and more useful than pure metals
111
how is an alloy different
different elements have different sized atoms, when another element is mixed the new metal atom will distort the layers, making it harder and less easy for it to slide over each other
