science Flashcards
(252 cards)
1
Q
democritus was a greek philosipher who propsed
A
matter could not be divided into smaller pieces forever;matter was made from small, hard particles called atoms
2
Q
john dalton confirmed atoms
A
are tiny solid balls and created the first atomic theory`
3
Q
jj thompson came up with the plum pudding model and discovered electrons with
A
cathode rays - he showed the atom was made of smaller things
4
Q
ernest rutherford discovered protons and the nucleus using his
A
gold leaf experiment
5
Q
in the gold foil experiment it was concluded there was a dense positive centre because
A
the alpha particles did different things - scattered, scattered a lot, and went through the foil
6
Q
niels bohr created the bohr model from discovering that
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every atom has a specific number of electron shells (and that there were shells )
7
Q
erwin schrodinger and werner heisenburg led to the idea of
A
electron clouds
8
Q
jameschadwick created the modern model which included
A
protons, electrons AND neutrons
9
Q
a physical change is one where
A
no new substances are formed. It is usually reversible
10
Q
physical change examples could be
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ice melting, melting chocolate, breaking a glass (solid, liquid, gas)
11
Q
a chemical change is a change in which
A
a new substance forms. It is irreversible.
12
Q
chemical change examples could be
A
cooking food, fireworks, leaves changing color
13
Q
what are some signs of a chemical change?
A
odour is given off
hear a bang/fizzing - effenresence; bubbles in a liquid, fizz
increase /decrease in temp
see fizzing/ change in color
14
Q
what is a precipitate?
A
a solid substance that forms at the bottom of a solution
15
Q
chemical changes happen when
A
chemical reactions occur
16
Q
chemical change involve
A
the formation of new chemical elements/compounds
17
Q
physical changes don’t lead to new chemical substances. instead,
A
a substance simply changes physical state (solid-liquid)
18
Q
reactants=products
A
reversible
19
Q
reactants-products
A
irreversible
20
Q
during irreversible chemical changes, the number of atoms stays the same either side whilst the products and reactants
A
simply rearrange
21
Q
exothermic
A
energy out to surroundings (temp up)
22
Q
endothermic
A
energy in from surroundings (temp down)
23
Q
potassium + nitrogen + oxygen -
A
potassium nitrate!
24
Q
in a word equation, if there is 3 reactants - including oxygen -
A
ate e.g. nitrate
25
in a word equation if there is 2 reactants - ending witth non-metal -
ide e.g. chloride
26
calcium + fluorine =
calcium fluoride
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H + O2 - H2O
4H + O2 - 2H2O
28
(s) = solid (l) =liquid (g) = gas
(aq) = aqueous - dissolved in water
29
balancing tip
LHS E RHS
1 C 1
30
PHOTOSYNTHEISIS -
converts light into chemical energy
31
cellular respiration -
breakdown of glucose to release energy
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rusting is iron reacting with
oxygen and water
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combustion is when fuel reacts with
oxygen to release energy
34
the law of conservation of mass
total mass of reactants
= -------------------------------------
total mass of products
35
when one of the products is a gas,
the mass does not/may not appear conserved - it may appear to be less than that of the reactants
36
when balancing chemical equations
-only change the molecule number
- whole numbers only
- tackle more unusual ones first
37
Aerobic respiration
occurs with oxygen and releases more energy but more slowly.
38
Anaerobic respiration
occurs without oxygen and releases less energy but more quickly.
39
example of endothermic reaction
photosynthesis
40
e.g. of exothermic reaction
cellular respiration
41
in photosynthesis (endothermic) light energy is converted into chemical energy which is stored in the bonds of
C6H1206 aka glucose
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carbon dioxide + water -
glucose + oxygen
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oxygen + glucose -
carbon dioxide + water
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products of photosynthesis become the reactants for
cellular respiration
45
rust = iron oxide
-compound
-powdery
-flakes
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formation of rust when a metal(iron) reacts
with oxygen in the presence of water
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steel contains iron and is therefore
prone to rusting
48
ways to prevent rust
painting, oiling, galvanising, covering in plastic
49
what is combustion?
burning - fuel combining chemically with o2 then releasing energy
50
complete combustion needs o2 -
carbond ioxide vs carbon
51
is combustion endo or exo thermic
exothermic becasue of the heat givem out to surroundings
52
what is the combustion word equation
fuel + oxygen - carbon dioxide + water (+energy)
53
to test for the presence of hydrogen you do the
squeaky pop test
54
energy def
energy is the ability to do work
55
energy measuring unit?
joules ( J )
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work done -
energy transferred
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energy cannot be created or
destroyed
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energy = E in
equations
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P =
e/t
60
what is Ek?
kinetic energy
61
what are the two main types of energy?
kinetic and potential
62
what is kinetic energy?
motion
63
what is potential energy
( stored due to the positioning
64
examples of kinetic energy
light energy, sound energy, a moving car or rolling ball
65
examples of potential energy
a streched rubber band, book on the shelf, GPE, nuclear energy
66
9 types of energy
chemical, thermal, light, sound, magnetic, gravitational, elastic, electrical, nuclear
67
4 ways energy can be transferred
electrically
heating
mechanically
radiation
68
transferred means
one store to another
69
transformed means
the process of changing energy from one form to another, like converting electrical energy inro light energy (bulb)
70
what does the law of conservation of energy state?
energy cannot be created or destroyed, only transformed from one form to another/transferred
71
what is useful energy?
energy which is required for the object to work e.g. with a car its kinetic
72
what is wasted energy?
energy that has been transferred to another store and isn't useful e.g. with a car its the thermal store
73
when a rollercoaster reaches the peak, what happens to the ke and gpe?
hight gpe and low ke
74
when a rollercoaster reaches the slope downwards, what happens to the ke and gpe?
high ke low gpe
75
when a rollercoaster starts climbing to the top, what happens to the ke and gpe?
low ke and high gpe
76
when electrical enrgy goes into a tv, what comes out?
light, sound and heat energy
77
when chemical potential enrgy goes into a torch, what comes out?
light energy and heat energy (wasted)
78
when electrical enrgy goes into a tv, what is the internal component?
electrical energy
79
when chemical potential enrgy goes into a torch, what is the internal component?
electrical energy
80
when electrical energy goes into a kettle, what comes out
thermal energy and sound energy
81
when cpe goes into a radio what comes out?
sound and heat energy
82
when cpe and kinetic energy (hands) goes into a guitar what comes out?
kinetic energy (strings), sound energy, heat
83
what is the energy transfer when a pen is dropped?
Ek in hand is transferred to pen which then had Ek
84
what is the energy transformation when a pen is dropped?
Ek of pen transforms into GPE as lifted - GPE of pen is transformed into kinetic energy when pen drops
85
what is the energy transfer when a guitar is strummed?
Ek in the hands to Ek in the strings
86
what is the difference between thermal and heat?
thermal energy is a store, heat is a transfer
87
GPE FORMULA
GPE = mgh
88
KE FORMULA
KE =1/2 mv (squared)
89
g - kg
divide by 1000
90
always do v squared first then
times it by 1/2 m
91
IN GPE YOU NEED KG AND M!
IN KE YOU NEED KG AND M/S
92
metalloids have
properties of both metals and non metals
93
metals are malle-
able
94
Malleable means you can beat it into
thin sheets ( e.g. gold)
95
metals are sono-
-rous
96
sonourous means capable
of producing a deep ringing sound
97
metals are lustrous. lustrous means shiny or
able to be polished
98
brittle means when hit, fractures without
elastic deformation (nonmetal)
99
conducter let
heat and electricity pass through easily - metal
100
Insulators donot
let heat and electricity pass through easily - non metal
101
copper -
cu
102
lead
pb
103
iron
fe
104
a pure substance consists only of one
element/compound
105
A mixture consists of two or more
element/compounds not chemically joined togeteher
106
all matter is made from
atoms
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atoms are made of even simpler sub-atomic particles -
protons, neutrons and electrons
108
9, F, 19
9 is the atomic number, F is the symbol, 19 is the atomic mass
109
electrons are in
orbits/shells
110
atomic number is
protons or electrons
111
atomic mass is
protons+ neutrons
112
a protons charge and relative mass is
charge +1 and relative mass is 1
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a neutrons charge and relative mass is
charge 0 and relative mass is 1
114
a electrons charge and relative mass is
charge -1 and relative mass is 0.0005
115
electrons maximum number of orbits is (from in - out)
2,8,8,2
116
atoms have a overall? charge
neutral
117
charged particles are
ions
118
+ CHARGED = p>e
cations
119
- CHARGED = p
anions
120
carbon dioxide and table salt are both
compounds
121
e.g. molecular structure
oxygen, co2,mwater, glucose
122
e.g. lattice structure
sodium chloride, diamond and graphite, silicon dioxide
123
matter occupies
space and has mass
124
there are 118
elements
125
elements are made of only
1 atom type
126
diatomic elements consist of
2 atoms e.g. o2
127
compounds are
2 or more different elements or types of atoms chemically joined togetehr
128
atoms are the smallest particles
substances can be broken down into
129
element exampless
o2, magnesium, calcium
130
compound examples
water, copper sulphate,
131
mixture examples
air, salt water, milk
132
single atoms are called
monatomic
133
clusters of molecules are
diatomic
134
lattices are
large grid like structures
135
molecule means
a group of atoms chemically joined together
136
elements and compound can have
entirely different properties
137
non metal elements tend to form
molecules
138
metal elements tend to form
lattic structures
139
most non metallic structures are made of
molecules
140
crystal lattices are
grid like structures that repeat the s arrangement of atoms over and over
141
diamond and graphite an dgraphene
are carbon allotropes
142
allotropes are
different structual forms of teh same element
143
describe a diamond
lots of bonds, no free electrons, high melting oint, hard and dense, doesn;t conduct electricity
144
describe graphite
weakly bonded delocalised electrons, high melting point, conducts electricity, soft and slippery
145
graphene is a
single layer of graphite
146
thermal energy is a
energy store
147
thermal energy is a measure of all
the total kinetic energy of all particles in a substance
148
the greater the volume the ? thermal energy
more ( more particles)
149
thermal energy always moves from
warmer - colder objects by heat transfer
150
thermal energy is measured in
joules (J)
151
Temperature is a measure of how
hot/cold a substance is
152
Heat is a type of energy
transfer
153
Heat is the amount of energy
that is transferred from one object to another due to temp difference
154
Heat travels from hot-
cold
155
thermal conductors allow heat
to transfer through easily
156
thermal insulators ? heat to transfer through
don't allow
157
The rate at which objects transfer enrgy ( or lose heat ) depends on:
- Sa - volume ratio
- The objects material
( conductor/insulator )
- The temp difference between the object and it's surroundings
158
high SA:V ratio means
high rate of energy transfer
159
conducting material means
high rate of energy transfer
160
high temp differnce means
high rate of energy transfer
161
Conduction state
solids
162
Convection state
fluids ( liquids + gases ) - particles
163
radiation
vacuum
164
conduction is the transfer of heat energy by
direct contact and the passing of vibration from a hot - cool object
165
convection is the transfer of heat energy by
liquid/fluid motion from a hot ocject to a cool one
166
an example of convection is
boiling water
167
Radiation is the transfer of heat energy by
waves from a hot - cool object
168
radiation has no involvement of particles, only waves - true or false
true
169
name some good conducters
copper, brass, silver, aluminum
170
name some good insulators
wood, plstic, paper, wool, foam, glass, air
171
In conduction, an object is heated - causing the atoms to
vibrate.
172
These Vibrations make the atoms next to them vibrate, and so on. This is how the heat energy
travels along a solid e.g. plastic and wood
173
Metals (then collide with neighbouring atoms ) contain free elctrons that aren't attcahed to the atom and are free to move around. The heat can be transferred faster than in a n insulating material bc
electrons have a smaller mass than atoms
174
high ke by heating means atoms collide with
neighbouring particles and energy is transferred.
175
When part of a liquid or a gas is heated, the particles gain
kinetic energy and move apart from each other
176
When heated, fluids become less dense and rise. Once that happens they cool down bc they are
further from the heat
177
The particles lose energy when cooling down and become more dense and closer together - making it
sink. This is how a convecton current happens
178
Heat Radiation can also be called
infrared radiation
179
Radiation travels fastest in a
vacuum ( at the speed of light )
180
Radiation can travel through
solids, lliquids and gases
181
poor absorbers are poor emitters
of radiation and emit much slower
182
why do polar bears cover their nose?
to minimize heat loss
183
the bigger the SA the more infrared waves can be emitted -
so the quicker the heat transfer
184
all things absorb and emit
infrared raduation
185
the hotter something is the ? infrared radiation it emits
more
186
Some things glow when they are hot- this means they are giving out
visible radiation as well as infrared radiation so we can see them.
187
Matte black surfaces aare very good
absorbers and emitters
188
Matte Black surfaces are very bad
reflectors
189
Shiny silvery white surfaces are very bad
absorbers and emitters
190
Shiny silvery white surfaces are very good
reflectors
191
What is Double glazing?
2 pieces of glass are used in a window with a gap in between filled with air/vacuum.
192
how does double glazing minimize heat loss in our homes?
It reduces heat loss through conduction a s air is and insulator A vacuum prevets loss by conduction and convection
193
What is a wall cavity insulation?
if the cavity ( gap ) in the wall is filled with only air, the air can move around and teransfer heat from the inner wall
194
how to minimize heat loss in radiators
aluminmunm foil between the radiator and the wall reflects the heat radiation away from the wall as silver is a good reflector
195
GPE =
Mgh
196
gpe is measured in
joules
197
in GPE - m ( mass ) is measured in
kg
198
in GPE - g ( gravity on earth ) is measured in
n/kg
199
in GPE - h ( height ) is measured in
m ( meters )
200
g on earth aka n/kg is
9.81 N/kg
201
what is one way a thermos works?
The plastic cap stops cooling by evaporation and convection and conduction
202
CO2 test is
cloudy lime water
203
Neutral oject
balanced number of + AND - CHARGE
204
Positive Object
more + than - charge
205
Negative Object
more - than + charge
206
Charged Object
unbalanced number of + and - charge
207
Atoms are neutral bc
Protons = Electrons
208
charged particles are called
ions
209
positively charged particle ( p>e )
cations
210
negatively charged particle ( p
anions
211
two oppositely charged objects means
attraction
212
two similarly charged objects means
repulsion
213
The moving of charges through electricity is a form of energy transfer - it can be referred to as
electrical energy which is a form of Ek ( when applied to moving charges )
214
3 elements of an electric circuit
1) an energy source e.g. battery
2) a conducting path e.g. wire
3) an energy user e.g. lightbulb
215
electrical circuit is a
closed loop
216
Current ( I ) is a measure of
the flow of electrons ( moving ) around the circuit
217
Potential Difference/Voltage ( V ) is the force
driving the flow of elecetrons provided by cell battery
218
an example of something for electrons to flow through
wire
219
current is measured in
amps using an ameter
220
1Amp =
1000 ma
221
what is the difference between a cell and a battery
A cell is a single device that converts chemical energy into electrical energy, while a battery is a collection of cells that provide a steady source of electrical energy.
A battery provides a higher voltage and more energy than a single cell.
222
the force that causes opposite charges to attract is called
electrostatic force
223
Electrons leave the - terminal of a power supply bc
they are repelled by the - terminal ( like charges repel )
224
Electrons move from the negative termina to the
positive bc opposite charges attract
225
We show the current moving from the positive to negative terminal
even though its wrong
226
a circuit that only has 1 path for the current to flow through is called a
series circuit
227
a circuit that has more than 1 patyh for the current to flow through is called a
parallel circuit
228
what are 2 adavantages of household wiring being on a parallel circuit?
1) some appliances can be on while others are off ( acheived by inserting switches )
2) if one appliance fails, the others will still work
229
Voltage is the
amount of energy used up by a charge ads it moves through a load/ressistor
230
Potential energy transformed as charge moves through a
component
231
Resistance ( R ) is measured in
ohms Ω
232
Resistance opposes the flow of charge in an
electric circuit
233
a resistor is a device
deliberately placed in a circuit to control the size of the current
234
high # of components means
high resistance
235
high temp of wire means
high resistance ( more cahllenging for electrons to get through )
236
Ammeters must be connected to
series circuit
237
Voltmeters must be connected to
parllel circuit
238
when in a series circuit, current
stays the same
239
when in a series circuit, voltage
splits
240
when in a parallel circuit, voltage
stays the same
241
when in a series circuit, current
splits
242
which time of diagram helps look at efficiency?
sankey diagram ( arrow )
243
Efficiency (%) =
useful energy output/total energy input x 100
244
P = e/t
power = energy/time
245
power is measured in
joules/second
246
joules per second is also known as
watts ( w )
247
1000w =
1KW
248
Kwh ( kilowatthour) is a
unit of energy
249
Why is efficiency important for personal cost?
pay less for the same output
250
Why is efficiency important for the environment?
Where does energy come from? - non renewable resources such as fossil fuels like coal, oil which contributes to global warming. We want renewable resources liek solar or tidal power
251
Cost =
power x time x tariff
Power = kw
time = hours
Tariff = 27.56
252
we want
50000 hours
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