Chemistry Yr 9 - EVERYTHING Flashcards
(93 cards)
1
Q
what is an atom
A
smallest part of an element that can exist
all substances are made up of atoms
2
Q
what is an element
A
are made up of one type of atom
3
Q
what are compounds
A
they are formed from an element by chemical reaction.
they contain two or more elements chemically bonded together
4
Q
what is the radius of an atom
A
1 x 10 to the power of -10
5
Q
what is the radius of the nucleus of an atom
A
1 X 10 to the power of -14
6
Q
what is the charge of a proton
A
+1
7
Q
what is the charge of a neutron
A
+0
8
Q
what is the charge of an electron
A
-1
9
Q
how do you find the atomic mass of an element
A
protons + neutrons
10
Q
how do you find the atomic number
A
the number of electrons or protons
11
Q
how to find the number of neutrons in an element
A
atomic mass - atomic number
12
Q
what did neils bhor discover
A
electrons orbit the nucleus at specific distances in fixed energy levels
13
Q
what did john Dalton discover
A
tiny spheres that couldn’t be divided
arranged elements in order of their atomic wieghts
14
Q
what did JJ Thomson discover
A
plum pudding model
tiny spheres of positive charge with negative charges spread easily
15
Q
what did James Chadwick discover
A
found evidence for the existence of neutrons in the nucleus
16
Q
what do metal atoms need to do in order to become positive ions
A
loos electrons
17
Q
what do non metal atoms need to do to become negative ions
A
gain electrons
18
Q
what is simple distillation
A
separating out a liquid from a solution
19
Q
what is fractional diistilation
A
separating mixtures of liquids
20
Q
what is filtration
A
separates insoluble solids from liquids
21
Q
what is evaporation
A
when liquids are heated into gases
22
Q
what is chromatography
A
process of separating components of a mixture
23
Q
what did john Newlands do
A
built on Daltons ideas
arranged elements in order of their mass
24
Q
what is a mixture
A
made up of two or more substances that are not chemically combined
25
what is ionic bonding
electrons are transferred from a metal to a non metal to create oppositely charge dions
26
Name the trends in Group 1?
Known as the Alkali Metals
Reactivity increases as you go down the group
metals
really reactive
melting + boiling point gets lower as you go down the group
27
Name the trends in group 7?
Known as the halogens
reactivity decreases as you go down the group
more reactive halogen will replace a less reactive halide
Highly reactive
non metals
28
Name trends in group 0?
known as the noble gases
unreactive
colourless and odourless
low melting points
non metals
non flammable
stable not needing to loose or gain electrons
29
Name similarities between group 1 and 7
highly reactive.
Both groups form ionic compounds
Their elements react with other groups to achieve a full outer shell of electrons.
30
What is ionic bonding?
the transfer of electrons between a metal and non-metal.
ionic bonds form between oppositely charged ions
31
what is covalent bonding
atoms are held together by sharing pairs of electrons between non metals
32
what is metallic bonding?
the electrostatic attraction between positive metal ions and a sea of delocalised electrons
33
name the physical properties in the halogens?
strong covalent bonds
weak intermolecular forces
low melting and boiling points
poor conductors of heat and electricity
34
Name the chemical properties of the halogens?
all have 7 electrons in their outer shell
they all want to gain one more electron to have a full outer shell either by ionically bonding or covalently bonding
35
Name the physical properties of group1
have very low density
very soft
can be cut with a knife and then goes dull as it oxidises
needs to be stores in oil to stop it reacting with the water ion the air
36
What did John Dalton contribute to the periodic table?
came up with the table of elements
elements where ordered by their atomic weights
37
What did Dmitri Mendeleev contribute to the periodic table?
he arranged the elements according to atomic weight
he grouped elements with similar properties together
he left gaps for unknown elements and predicted what their properties would be when the elements where discovered they matched his predictions and his table was accepted by the scientific community
38
why was the periodic table being developed?
chemists tried to classify the elements it arranges them in an order which is similar elements are grouped together
39
What are intermolecular forces?
they are weak forces if attractions between molecules influencing their physical properties like melting/boiling points and states of matter
40
Why did scientists reject Newlands ideas?
his law of octaves broke down after calcium
he put elements with different properties in the same group instead prioritising atomic weight
he didn't leave gaps for unknown elements
41
What state is astatine at room temperature?
Solid
42
name two differences you would see between the reactions of potassium and lithium with water
potassium reacts much faster as it moves around on the surface
potassium reacts more violently as its lower down the goup
43
what elements are often used as catalysts
transition metals
44
in a modern periodic table the elements are arranged in order of blank
atomic number
45
formula of astatine?
At2
46
when anything is reacted with group one what gas is released?
hydrogen
47
in a modern periodic table how are elements ordered?
by atomic number
48
What did John Newlands contribute to the periodic table?
the law of octaves but broke down after calcium
built on Daltons ideas and arranged the known elements by atomic mass
49
Properties of metals
shiny
mostly solid
dense and strong
good heat
good electrical conductors
50
properties of non metals
dull
low density
weak
brittle
poor heat
poor electrical conductor
51
in group 0 does the boiling point increase or decrease as you go down the group?
increases
52
What's the modern name for atomic weight?
relative atomic mass
53
Why did Mendeleev reverse the order of tellurium and iodine?
he reversed them as his periodic table was also based on the elements properties not just their atomic weight.
54
why did scientists accept Mendeleev's ideas?
he accurately placed elements by their chemical properties and atomic mass
he left gaps for undiscovered elements
his predictions of unknown elements where accurate so when those elements where discovered they had a place on the table
55
whats oxidation
the loss of electrons
56
whats reduction
the gain of electrons
57
what is crude oil
a finite resource found in rocks
formed by the remains of ancient biomass
a mixture of hydrocarbonsw
58
what are hydrocarbons
hydrocarbons are made up of hydrogen and carbon atoms only
59
what is the formula for alkanes
CnH2n+2
60
what are the first 5 alkanes
methane
ethane
propane
butane
pentane
61
what is the molecular formula of ethane
C2H6
62
What is the structural formula of ethane
CH3 CH3
63
what is the displayed formula for ethane
H H
I I
H - C - C - H
I I
H H
64
what does non renewable mean
cannot be replaced
65
what does renewable mean
can be replaces
66
what does saturated mean
it has no double bonds
67
what is the homologous series
series of compound with similar chemical properties that differ by CH2
68
what is the method of carrying out fractional distilation
crude oil is heated to make a vapour
vapour rises up the column
the column is hot at the bottom and cooler at the top
hydrocarbons condense at different temperatures depending on their boiling points
69
what are the properties of hydrocarbons with small molecules
low boiling points
very volatile
flows easily
ignites easily
70
what are the properties of hydrocarbons with large molecules
high boiling point
not very volatile
doesn't flow easily
doesnt ignite easily
71
what does it mean by volatility
tendency to turn into a gas
72
what does it mean by viscosity
how easily it flows
73
what does the complete combustion of hydrocarbons produce
carbon dioxide
water
74
what the formula for alkenes
CnH2n
75
what is a fraction?
a set of hydrocarbon molecules of similar size and boiling points
76
what are the products of incomplete combustion?
carbon monoxide
77
how many bonds do alkenes have?
double
78
what is cracking?
when hydrocarbons are broken down to produce smaller molecules
79
what reacts with alkenes
bromine water
80
what colour would bromine water turn if alkenes was present?
colourless
81
what are more reactive akenes or alkanes?
alkenes
82
first four alkenes?
ethene, propene, butene, pentene
83
why are alkene molecules unsaturate?
they contain two fewer hydrogen atoms than alkanes
84
what are alkanes?
saturated hydrocarbons that only contain single bonds between carbon and hydrogen atoms.
have the general formula CnH2n + 2
85
what's the word equation for the reaction of octane with oxygen
Octane + Oxygen → Carbon dioxide + Water
86
which stores in energy moved to and from in an exothermic reaction
from the thermal store to the chemical store
86
what is an endothermic reaction
when energy is moved into the system
86
what is an exothermic reaction
when energy exits from the system into the surroundings
87
what are the differences between endothermic and exothermic reactions
endothermic - energy s taken in by the reaction
- energy in the surroundings decrease
- temp in the surroundings decrease
- energy enters the chemicals
88
What is the plum pudding model
ball of positive charge (spread electrons spread throughout (embedded in the ball of positive charge) electrons outside the nucleus
no empty space in the atom
89
what is the nuclear model
positive charge concentrated at the centre
most of the atom is empty space
mass concentrated at the centre
90
name two properties of ionic substances
high melting point
dissolve in water
91
Is forming a bond an exothermic or endothermic process?
exothermic
