C1 Flashcards
(133 cards)
1
Q
What is an element
A
All atoms are the same
2
Q
How many elements are in the periodic table
A
100
3
Q
What does each element represent
A
Different atoms with different symbols
4
Q
What is a compound
A
Two or more elements chemically combined in a fixed proportion
5
Q
What do we do to break compounds back into elements
A
We use chemical reaction
6
Q
Different elements or compounds NOT chemically combined together
A
Mixtures
7
Q
If we want to separate a ——- then we use physical techniques
A
Mixture
8
Q
What physical techniques do we use to separate a mixture
A
Filtration crystallisation,distillation
9
Q
Define molecule
A
Any elements chemically joined,can be same element unlike compound which needs different ones
10
Q
What is an atom
A
Smallest part of an element, no overall electrical charge,all substances are made of atoms
11
Q
Radius of an atom
A
0.1nm
12
Q
What are physical separation techniques used for
A
Mixtures
13
Q
What can physical techniques not be used to separate and why?
A
Elements in a compound because they are chemically combined in a fixed proportion
14
Q
What is filtration
A
Used to separate insoluble solid from liquid
15
Q
What is crystallisation
A
Used to separate soluble solid from liquid
16
Q
What is simple distillation
A
Used to separate liquid from solid if we want to keep liquid
17
Q
What is fractional distillation
A
Allows us to separate 2 different liquids
18
Q
What is chromatography
A
Physical process used to separate mixtures
19
Q
What does chromatography work
A
Because each chemical in mixture is attracted to the stationary phase to a different extent
20
Q
What are atoms not
A
Divisible
21
Q
Who invented the plumb pudding model
A
JJ Thompson
22
Q
What does the plum pudding model show
A
An atom is a ball of positive charge with negative electrons embedded in it. Was WRONG!
23
Q
Who did the alpha scattering experiment
A
Rutherford
24
Q
Why did Rutherford experiment using a piece of gold foil
A
Can be hammered down to be a few atoms thick
25
Results from alpha scattering experiment (3 marks)
- most alpha particles went straight through the gold atoms
-some deflected (changed direction)
-bounced straight back
26
Most alpha particles went straight through gold atoms. Why?
Atoms are mainly empty space
27
Some alpha particles defelcted. Why?
Centre of atom must have positive charge- alpha particles close to this repell/ change direction
28
Alpha particles bounced straight back. Why?
Centre of atom must contain great deal of mass- now call this a nucleus
29
What did James chadwick discover
Nucleus also contained neutral particles called neutrons
30
Example of substance that you can filter
Silver chloride + water
AgCl= solid
H20= liquid
31
Example of substance you can crystallise
Sodium chloride + water
NaCl = aqueous- forms crystals
H20= water- evaporates
32
Equipment needed for filtration
Filter paper
Filter funnel
Beaker
33
Equipment needed for crystallisation
Beaker
Evaporating basin
Bunsen burner- if u wish to heat substance- don't over heat otherwise compounds will start to break down
34
How does simple distillation work
- First evaporate liquid by heating
- we then condense water by cooling
35
Can fractional distillation work if liquids have same m.p/ b.p
No, otherwise we won't be able to collect pure form
36
What is fractional distillation used for
To purify larger volumes of liquid e.g. crude oil- requires different equipment but principle is same
37
How do you know if a chemical is pure in chromatography?
Will produce a single spot in all solvents
38
What chemicals will move further up chromatography paper?
Chemicals that are weakley attracted to stationary phase
39
Why do we draw a line in pencil on chromatography paper
It's insoluble
40
What is the solvent called in chromatography
Mobile phase because it doesn't move
41
Soluble meanning
Can dissolve in water
42
Insoluble meanning
Can't dissolve in water
43
Solute meanning
Dissolved in solvent
44
Solvent meaning
Dissolves solute resulting in solution
45
What's the nuclear model (3)
- negative electrons around the edge
- tiny positive nucleus
- empty space
46
What was Niels Bohr model
- belived electrons orbited nucleus at specific distance (now call this orbit or energy levels/shells)
- several years later discovered protons- positive charge in nucleus
47
What was the final version of nuclear model
- atoms have no overall charge because number of electrons is the same as number of protons
48
What is radius of nucleus
1 x 10 ^ -14
49
Relative charge and mass of protons
Charge= +1
Mass= 1
50
Relative charge and mass of neutrons
Charge= 0
Mass= 1
51
Relative charge and mass of electrons
Charge= -1
Mass= very small
52
How does energy progress through the outer shells
shell- further away from nucleus= higher energy
53
What charge does the nucleus overall have
Positive because of protons
54
What happens if an atom absorbs electromagnetic radiation
An electron can move from a lower energy shell to a higher energy shell/level
55
How can electrons change energy levels/ shells
By absorbing or emitting electromagnetic radiation
56
What is the structure of how many electrons can be present in each shell
2, 8,8,18
57
The group number represents...
The number of electrons on outer shell
58
What is the relative atomic mass
Protons and neutrons- the bigger number
59
What is the atomic number
Smaller number
60
What did Döbereiner discover
- elements with similar properties occurred in 3s [triads]
- e.g. Lithium, sodium, potassium (all react rapidly with water)
- Chlorine, Bromine, Iodine (all reactive non-metal)
61
Work of Newlands...
Octaves
62
What was Newlands law of octaves
- arranged elements in order of Increasing atomic weight- every 8th reacts in similar way
- e.g. lithium, sodium, potassium
63
What was the problem with Newlands discovery
- by always sticking to exact order of atomic weight sometimes elements were grouped together when they had different properties
64
Who was the Russian scientist
Dmitri Mendeleeve
65
What did Mendeleeve do
- arranged elements by order of Increasing atomic weight
- If needed he would switch order of elements to fit pattern of other elements in same group
- realised some elements had not been discovered so left gaps in periodic table
66
What 3 things did Mendeleeve do that no other scientist did
- would switch order of specific elements to fit partern of other elements in same group
- realised some elements had not been discovered- left gaps
- predicted properties of undiscovered elements based on the group- he was correct elements discovered fit his periodic table
67
What are the differences between Mendeleevs table and modern periodic table
- protons had not been discovered- he ordered them with atomic weight ( elements could be in wrong order due to isotopes)
- modern includes noble gases which weren't fully discovered when Mandeleev published his table
68
What are group 0 known as
Noble gases- monatomic gases (singles atoms- not bonded)
69
How many electrons do nobles gases have in outer shell
8- full, energetically stable except helium which has 2
70
List properties of Group 0 (4)
- inert: don't react, non flammable
- colourless gases
- do not form molecules
- unreactive elements
71
What is the trend in noble gases (4 marks)
Boiling point Increases as you move down the group along with relative atomic mass
- atoms become larger intermolecular forces between atoms gets stronger- more energy Is needed to overcome the forces
72
Why does Boiling point Increases as you move down group 0
- atoms become larger intermolecular forces between atoms gets stronger- more energy Is needed to overcome the forces
73
How do noble gases react
Very unreactive as they have full outer shell
74
What are group 1 known as
Alkali metals
75
Group 1 have .... electrons in outer shell
1
76
How reactive are group 1 elements
Very reactive because they can lose the one electron in outer shell
77
Properties of Group 1 elements
- soft (can be cut with a knife)
- low density (first 3 are less dense than water)
- low m.p and b.p- decreases down the group
- form ionic compounds with non- metals
78
Describe the trend in group 1 elements
- Increasing reactivity as you move down the group- outer electron is more easily lost as attraction between the nucleus and electron decreases as electron is further from nucleus
- hence electron is lost easier as you move down group
- lower m.p. and b.p. as you move down
- higher relative atomic mass- atoms become larger
79
List the reactions of group 1 elements with water, oxygen and chlorine
Metal + water = metal hydroxide and hydrogen
Metal + oxygen= Metal oxide
Metal + chlorine = Metal chloride
80
Lithium + water =?
Lithium hydroxide + hydrogen
81
What is the formula for lithium reacting with water
2Li + 2H₂0 = 2LiOH + H₂
82
What are the observations for when lithium reacts with water
- fizzes steadily but furiously along surface
- slowly becomes smaller until dissappears
83
Sodium + water =?
Sodium hydroxide + hydrogen
84
Formula for sodium reacting with water
2Na +2H₂0 =2NaOH + H₂
85
What's the observations when sodium reacts with water
- fizzes rapidly, melts to form a ball
- quickly becomes smaller until it dissappears- more violent than lithium
86
Potassium + water =?
Potassium hydroxide + hydrogen
87
Formula of potassium reacting with water
2K + 2H₂0 = 2KOH + H₂
88
Observations made when potassium reacts with water
- burns violently with a spark and lilac flame
- quickly melts to form a ball
- dissappears rapidly often with small explosion
- hot enough to ignite hydrogen gas
- very violent
89
Lithium + chlorine
Lithium chloride
90
Formula for lithium and chlorine
2Li + Cl₂ = 2LiCl
91
Sodium + chlorine
Sodium chloride
92
Potassium + Chlorine
Potassium Chloride
93
Formula for sodium and chlorine
2Na + Cl₂ = 2NaCl
94
Formula for potassium and chlorine
2K + Cl₂ = 2KCl
95
Observations made during reaction of lithium, potassium and sodium with chlorine
- act vigorously when heated in chlorine gas to form white metal chloride salts
- as you move down relativity increases so reaction with chlorine gas gets more vigorous
96
Lithium + oxygen
Lithium oxide
97
Sodium + oxygen
Sodium oxide
98
Potassium + oxygen
Potassium oxide
99
Formula for lithium reacting with oxygen
4Li + O₂ = 2Li₂O
100
Formula of sodium reacting with oxygen
4Na + O₂ = 2Na₂O
101
Formula for when potassium reacts with oxygen
4K + O₂ = 2K₂O
102
Observations made when group 1 alkaline metals react with oxygen
- burn vigorously when heated and placed in a gas jar of oxygen
- oxide forms white smoke
- as reactivity increases down group so does reaction with oxygen
103
What are group 7 called
Halogens
104
How are halogens found
Diatomic molecules joined together by single covalent bond
105
Properties of Group 7 [7]
- non metals
- coloured vapours: poisonous
- diatomic molecules
- form 1- ions
- ionic bonds with metal halide
- displacement reaction can occur between more reactive halogen and salt of less reactive one
- all have 7 electrons in outer shell
106
What colour is fluorine gas
Yellow- very reactive
107
What colour is chlorine gas
Dense green gas- fairly reactive
108
What colour is bromine
Red brown volatile liquid= dense
109
What colour is iodine
Purple vapour- dark grey crystalline solid
110
What happens to molecules as you move down group 7
Molecules become larger, intermolecular forces become stronger, more energy Is needed to overcome these forces
111
What happens to reactivity as you move down group 7
- halogens become less reactive- harder to gain extra electron because outer shell Is further from nucleus
112
What happens to m.p and b.p as you move down group 7
Increases along with relative atomic mass
113
At room temperature what is Flourine
Gas
114
At room temperature what is chlorine
Gas
115
At room temperature what is Bromine
Liquid
116
At room temperature what is Iodine
Solid
117
What happens when halogens react with metals
- produce salt- made of ions which are held together by ionic bonding
118
What does Halogen mean
Salt producing
119
What happens as you move down group 7 to the reactivity
Reactivity of elements decreases down group
120
What happens to force of attraction as you move down group 7
Force of attraction between nucleues and outer shell decreases
121
What happens when halogen reacts with hydrogen
Product= Compound called hydrogen halide
- gases at room temperature + dissolve in water to produce acidic solutions
122
What do group 7 form when they react with other non- metal atoms
Covalent compounds
123
In this reaction what is displaced:
Sodium bromide + fluorine = sodium fluoride + Bromine
- fluorine displaces Bromine
- because fluorine is more reactive than Bromine
124
What do group 7 elements form when they react with metals
Ionic compounds
125
What bonds do group 7 make
Ionic bonds with metal halide
126
What do group 1 elements form
Ionic bonds with non metals
127
Define Isotope
Atoms have same number of protons and electrons but different number of neutrons
128
Do isotopes have same chemical properties
Yes because they have same electronic structure
129
How do you find the relative atomic mass of isotopes
(Isotopic mass x%abundance ) +(Isotopic mass x % abundance) /100
E.g. chlorine has 2 isotopes
Cl 35- 75%
Cl 37- 25%
[(75 x 35) + (25 x 37)] /100
= 35.5
130
What elements react to form positive ions
Metals
131
What elements do not form positive ions
Non- metals except hydrogen
132
Compare transition metals with group 1 metals
- have higher m.p. (except Mercury)
- have higher densities
- are stronger
- are harder
- much less reactive so do not react as vigorously with oxygen or water
133
Properties of transition metals
- have ions with different charges
- form coloured compounds
- useful as catalysts
