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Yr8-Science > y9 Science revision > Flashcards

y9 Science revision Flashcards

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1
Q

define an element

A

contains only one type of atom

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2
Q

define a compound

A

two or more different atoms chemically joined/ bonded together

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3
Q

define a mixture

A

two or more different elements or compounds NOT chemically joined/ bonded together.

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4
Q

define an atom

A

smallest particle of an element that is involved in a chemical reaction

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5
Q

define a molecule

A

two or more atoms chemically joined/ bonded together

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6
Q

what is shown on the left side of a chemical reaction?

A

reactants

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7
Q

what is shown on the right side of a chemical reaction

A

products

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8
Q

write a word equation for the formation of water from the reaction between hydrogen and oxygen

A

hydrogen + oxygen —> water

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9
Q

write a symbol equation for the formation of water from the reaction between hydrogen and oxygen

A

H2 + O2 —> H2O

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10
Q

define a solute

A

a substance that dissolves in a solvent

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11
Q

define a solvent

A

liquid that can dissolve a solute

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12
Q

define a solution

A

a mixture of a solute and solvent

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13
Q

how can an insoluble solid be separated from a liquid?

A

filtration

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14
Q

how can a soluble solid be separated from a solution

A

evaporation then crystallisation

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15
Q

how can immiscible (don’t mix) liquids be separated?

A

Use a pipette to extract one layer of liquid

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16
Q

how can miscible (do mix) liquids be separated?

A

distillation

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17
Q

what physical property is used in distillation?

A

boiling points - separates at different temperatures

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18
Q

what are the 3 steps in distillation?

A

evaporate, condense and collect

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19
Q

what is chromatography?

A

separates colours in mixture

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20
Q

what are the 5 models of the atom?

A

Tiny spheres, Plum pudding,Nuclear, Bohr’s and today’s model

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21
Q

who was responsible for each model of the atom?

A

J Dalton - Tiny spheres, JJ Thomson - Plum pudding, E Rutherford - Nucleus, Niels Bohr - Bohr’s, J Chadwick - Today’s model

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22
Q

describe the plum pudding model

A

solid ball of positive charge with electrons embedded throughout it

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23
Q

describe the nuclear model

A

positive nucleus at the centre, with electrons at the edge of the atom - rest is empty space

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24
Q

what evidence gave the nuclear atom as mainly empty space?

A

Positive Helium nucleus (alpha particle) fired at a gold foil - many went straight through

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25
what evidence gave the nuclear atom as having a positive nucleus?
Positive Helium nucleus (alpha particle) fired at gold foil - some slightly deflected as they went past the edge of the nucleus. Those fully deflected were repelled by the nucleus
26
what did Bohr’s model change about the nuclear model?
Electrons were no longer at the edge of the atom but in energy shells
27
how did today’s atomic model change from Bohr’s?
Discovery of neutrons, now added these to the nucleus
28
what is the order of the discovery of the sub atomic particles?
Electron, proton then neutron last
29
what is the mass of each sub atomic particle?
Proton = 1, Electron = almost one, Neutron = 1
30
what is the charge on each subatomic particle?
``` Protons = +1 Electrons = -1 Neutrons = 0 ```
31
where is most of the mass of an atom found?
in the nucleus
32
what subatomic particles are found in the nucleus?
protons and neutrons
33
where are electrons found?
in energy shells orbiting the nucleus
34
why does the atom have no overall charge?
number of protons = number of electrons
35
what does the relative atomic mass represent?
protons and neutrons
36
what does the atomic number represent?
Number of protons = number of electrons
37
how do you calculate the number of neutrons in an element?
Mass number - Atomic number
38
what are the numbers of electrons allowed in the electron shells?
1st she’ll = 2 electrons, 8 electrons are allowed in every shell after that
39
what is the electron configuration showing?
the number of electrons in each shell (e.g. 2,6)
40
Define an isotope?
Atoms are the same elements with a different number of neutrons
41
Approximately how large are atoms?
Radius is about 0.1nm
42
how large is the nucleus compared to the whole atom?
about 1/10000 the size
43
What is abundance?
The % of atoms in a sample with a particular mass
44
in the modern periodic table, how are the atoms arranged?
By their atomic number and in groups according to chemical properties
45
why do elements in the same group have similar properties?
because they all have the same number of electrons in their outer shell
46
before the discovery of protons, neutrons and electrons, how did scientists organise the elements?
by their atomic weight
47
why did Mendeleev leave gaps in his periodic table?
for elements that had not yet been discovered
48
which discovery meant that organising elements by their atomic weight not always correct?
Isotopes
49
where are metals on the periodic table found?
to the left and bottom of the periodic table
50
what are the names of groups 1, 7 & 0?
1 = Alkali metals, 7 = Halogens, 0 = Noble gases
51
why are noble gases inert (unreactive)?
they have a full outer shell of electrons so don’t need to lose or gain electrons to be stable
52
what does the group number tell you?
number of electrons in outer shell
53
what does the period number tell you?
number of electron shells
54
give some properties of group 1 metals
silver coloured, shiny, soft and very reactive
55
why are group 1 metals more reactive as you go down the group?
larger atoms so outer electron is further away from the attractive positive nucleus, so electron is more easily lost
56
what do group 1 metals produced when added to water?
Metal Hydroxide + Hydrogen
57
are halogens metals or non - metals?
non - metals
58
why are group 7 halogens more reactive as you go up the group?
smaller atoms so outer electron is closer to the attractive positive nucleus, so easier to attract an electron
59
what is the central block in the periodic table called?
transition metals
60
compare the hardness of group 1 & transition metals
Transition metals are much harder than group 1 metals
61
state which cell is smaller: a prokaryote cell or eukaryote cell
prokaryotic
62
give one example of a prokaryotic cell and two examples of eukaryotic cells
``` Prokaryotic = bacteria Eukaryotic = animal and plant cells ```
63
state 2 small similarities between a prokaryotic and eukaryotic cell
Both have a cytoplasm | Both have a cell membrane
64
state one difference between prokaryotic and eukaryotic cell
eukaryotic cells have genetic material enclosed in a nucleus Prokaryotic cells do not have genetic material enclosed in a nucleus. It is a single DNA loop
65
Parts of a bacterial cell
``` cell membrane cell wall circular strand of DNA Plasmid Cytoplasm ```
66
state how you convert from centimetres (cm) to millimetres (mm)
times by 10
67
state how you covert from millimetres (mm) to micrometers ( um)
times by 1000
68
what is the function of a nucleus
contains genetic information in the form of chromosomes and controls the activities of the cell
69
what is the function of the cytoplasm?
where many chemical reactions occur in a cell. It contains many enzymes for these reactions
70
what is the function of a cell membrane?
partially permeable; controls the movement of substances into and out of the cell
71
what is function of a mitochondria?
this is the site of aerobic respiration and release of energy
72
what is the function of a ribosome?
this is the site of protein synthesis
73
what is the function of a chloroplast?
Contains a green pigment called chlorophyll which absorbs light for photosynthesis
74
what is the function of a vacuole?
stores sap ( a weak solution of salts and sugars)
75
what is the function of a cellulose cell wall?
Rigid; supports and strengthens the cell
76
what is the function of a plasmid?
a small ring of additional DNA found in bacteria
77
state three organelles that present in a plant cell that are not present in an animal cell?
chloroplast vacuole cellulose cell wall
78
state one organelle that is present in both bacteria and plant cells
cell wall (however only the plant cell wall is made of cellulose) Or cell membrane Or cytoplasm
79
state two. differences between a bacterial cell (prokaryote) and a plant cell (eukaryote)
plant cells contain genetic information in a nucleus and bacteria do not plant cells contain mitochondria and bacteria do not
80
recall the equation for calculating magnification
magnification = size of image/ size of object (actual size)
81
describe and explain the function of sperm cells as a specialised cell
contain many mitochondria in their mid - piece for energy to move. Have a flagellum (tail) to swim towards the egg cell
82
describe and explain the function of muscle cells as a specialised cell
contain many mitochondria which supplies energy for muscle contraction
83
describe and explain the function of root hair cells as a specialised cell
contain many mitochondria to supply energy for active transport of ions
84
describe and explain the function of leaf palisade cells as a specialised cell
contain many chloroplasts which contains chlorophyll to absorb light for photosynthesis
85
describe and explain the function of xylem as a specialised cell
dead, hollow cells with no cytoplasm that join to end to end to form xylem tubes for the transport of water freely up the plant. The cell walls are strengthened with lignin
86
describe and explain the function of phloem as a specialised cell
cells joined end to end to form phloem tubes. Phloem cells have very few organelles e.g. no mitochondria to allow more room for the transport of cell sap

Yr8-Science (8 decks)

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