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Atomic Structure & Periodic Table Flashcards

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1
Q

What was John Dalton’s theory about the development of the atom? (4 marks)

A

Matter is made of atoms which are tiny particles that cannot be created, destroyed, or divided
Atoms of the same element are identical, and atoms of different elements are different
Different atoms combine together to form new substances

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2
Q

What did J.J Thompson’s plum pudding model suggest about the atom?

A

Atoms have no overall charge. There must be a positive charge to balance out the negative charge.
The plum pudding model contains electrons within a positively charged ball. The electrons are arranged randomly within a positive charge and the mass is spread evenly throughout the atom.

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3
Q

How did Rutherford explain the scattering of alpha particles by gold atoms?

A

A positive charge is concentrated in the centre of the atom, so like charges will repel.

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4
Q

What does Rutherford’s nuclear model suggest?

A

Most of the atom’s mass is concentrated in the nucleus, which contains positively charged particles. The atom consists mainly of empty space and the electrons orbit around the nucleus (cloud).

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5
Q

What was Rutherford’s experiment?

A

Rutherford shot a beam of positively charged particles (alpha particles) at a thin sheet of gold foil

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6
Q

What were the expected results in Rutherford’s experiment?

A

He expected the particles to pass through the foil because the positive charge of the nucleus was thought to be evenly spread out.

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7
Q

What were the actual results of Rutherford’s experiment

A

Some particles were scattered, however, a few were deflected directly back.

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8
Q

What was John Dalton’s suggestion for the periodic table?

A

He arranged the elements in order of their atomic weights.

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9
Q

How did John Newland build on John Dalton’s ideas?

A

He arranged the known elements in order of mass but noticed that the properties of every eighth element seemed similar. Hence he produced a table showing the ‘Law of Octaves’.

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10
Q

What was the problem with John Newland’s ‘Law of Octaves?’

A

He assumed all the elements have been found, even though chemists were still discovering new ones.
He filled in his octaves even if the elements weren’t similar.
The table only worked for known elements up to calcium (16) before the pattern broke down.

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11
Q

How did Mendeleev set up the modern periodic table?

A

He placed the elements in the order of their atomic weights.
He then arranged the elements so that a periodic (regularly occurring)
pattern in their properties could be seen.

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12
Q

How is the periodic table based on atomic structure?

A

The atomic number gives the number of electrons
The elements are ordered by the number of protons they have
The elements are put in groups where the number of shells increases as you go down the group.

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13
Q

Why were some elements not placed in the order of increasing atomic weight in Mendeleev’s periodic table?

A

So that the elements could fit into the proper groups (similar elements have similar chemical properties)

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14
Q

What did the Bohr Model suggest about electrons? (4 marks)

A

That electrons orbit the nucleus in fixed shells located at set distances from the nucleus. Each shell has a different energy associated with it, with the higher energy shells being located further away from the nucleus.

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15
Q

How did the Bohr Model prevent the atom from collapsing and why?

A

The orbiting of the electrons prevents the atom from collapsing inwards due to the attraction between the positive nucleus and negative electrons circling the nucleus.

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16
Q

What did James Chadwick’s experiment provide evidence for?

A

The neutron, which must have no charge and the same mass as a proton

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17
Q

Why is the ending of -ide used in ionic compounds?

A

-ide is used if the compound contains just two elements

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18
Q

Why is the ending of -ate used for ionic compounds?

A

-ate is used if the compound contains three or more elements, one of which is oxygen

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19
Q

Why are group 1 metals known as alkali metals?

A

They form alkaline solutions when they react with water. An alkaline solution is formed when a base solid dissolves in water.

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20
Q

What are the properties of group 1 metals? (3 marks)

A

They are all soft metals that can be easily cut with a knife.
They are very reactive (as they only need to lose one electron in order to become stable)
They have relatively low densities and low melting points.

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21
Q

Why do alkali metals have similar chemical properties?

A

They have 1 electron in their outer shell which determines their reactivity.

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22
Q

Why do the melting points of the alkali metals decrease as you go down the group?

A

The increase of shells decreases the attractive forces between outer electrons and positive ions

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23
Q

What compunds are formed when a group 1 metal reacts with a non-metal?

A

When a group 1 element reacts its atoms only need to lose one electron, as there is only 1 electron in the outer shell. Hence they form ionic compounds with 1+ ions.

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24
Q

Why do alkali metals get more reactive as you go down the group? (6 marks)

A

The atoms of each element get larger
going down the group, this causes an increase of shells.
This means that the outermost electron gets further away from the nucleus, so there are weaker forces of attraction between the outermost electron and the nucleus.
Therefore, less energy is required to overcome the force of attraction so the outer electron is lost more easily in reactions.

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25
Group 1 metal reaction with water | lithium + water ---> .......... + ..........
lithium + water ---> lithium hydroxide + hydrogen
26
Group 1 metal reaction with water | Li + H₂O ---> .... + .....
Li + 2H₂O ---> 2LiOH + H₂
27
How does lithium react when placed in water?
It's a relatively low reaction. There is some fizzing.
28
How does sodium react when place in water?
A large amount of heat is released which causes the sodium to melt and form a ball. Hydrogen released catches fire and causes the ball of sodium to dash across the surface.
29
How does potassium react when placed in water?
There is enough heat released so the hydrogen burns with a lilac flame The potassium melts into a shiny ball that dashes across the surface.
30
Group 1 metal reaction with oxygen | Sodium + Oxygen ---> .........
Sodium + Oxygen ---> Sodium Oxide
31
Group 1 metal reaction with oxygen | Na + O₂ ---> ......
4Na + O₂ ---> 2Na₂O
32
Why do alkali metals tarnish when exposed to air?
Because they form thin layer of oxide on their surface, which in turn react with moisture to form hydroxides.
33
Group 1 metals with chlorine | Potassium + chlorine ---> .....
Potassium + chlorine ---> Potassium Chloride
34
Group 1 metals with chlorine | 2K + Cl₂ ---> ....
2K + Cl₂ ---> 2KCl
35
What do group 1 metals react with chlorine to form? | the same for iodine, bromine, fluorine
They produce metal chlorides.
36
What are the physical properties of the transition metals?
They are very lustrous (shiny), they are hard and strong, and they are good conductors of both heat and electricity. Transition metals have a high density and high melting points.
37
What are ions?
They are charged particles.
38
When are ions formed?
When atoms gain or lose electrons in order to become stable.
39
How are ionic compounds formed?
When two ions have opposite charges, they are attracted to each other by electrostatic forces.
40
How are regular lattice structures formed?
If each ion is attracted to all those around it in all directions.
41
What are the physical properties of ionic compounds? (2 marks)
They have high melting and boiling points and they are good conductors of electricity (when melted or dissolved in water).
42
Why do ionic compounds have high melting and boiling points? (4 marks)
It takes a lot of energy to overcome the strong electrostatic forces of attraction between oppositely charged ions, which can only happen at high temperatures.
43
Why do ionic compounds conduct electricity when melted or dissolved in water?
When ionic compounds are in their solid form, they are fixed. However, when they are melted or dissolved in water their ions are free to move around. So the charged particles can conduct electricity.
44
What is the formula for hydroxide ions?
OH-
45
What is the formula for sulfate ions?
SO₄²-
46
What is the formula for nitrate ions?
NO₃−
47
What is the formula for carbonate ions?
CO₃²-
48
Why can transition metals have more than one oxidation state (charge on an ion)?
They can lose a different number of electrons, depending on the chemical environment they are in. Therefore, they can make more than one ion.
49
What happens to compounds containing transition elements in different oxidation states?
They form coloured compounds in aqueous solutions
50
What are the uses of transition metals in the industry?
They are used as catalysts, which are substances that speed up the rate of reaction but are not used up in the reaction. They are used in alloys, such as nickel in stainless steel. They are used in jewellery and anti-corrosive materials.
51
Why do transition metals have catalytic characteristics?
They have the ability to change oxidation states
52
What are some of the common transition metals uses as catalysts?
Iron is used in the Haber process. | Nickel is used in the hydrogenation of alkenes.
53
What do covalent bonds happen between?
Non-metals
54
What are the ways to display covalent bonds?
Dot and cross diagrams | Displayed formulas
55
What does the displayed formula look like for Ammonia?
H - N - H | H
56
What are the types of substances covalent bonds can make?
Simple molecular substances | Giant covalent structures
57
Why do simple molecular substances have low melting and boiling points? (1 mark)
Very little energy is needed to overcome the weak intermolecular forces
58
What are simple molecular substances? (3 marks)
They are small molecules in which the atoms of the molecule are joined by strong covalent bonds, that require lots of energy to break. However, between the molecules, there are only weak intermolecular forces.
59
Why does the melting and boiling point of simple molecular substances increase as intermolecular forces increase? (4 marks)
Although individual intermolecular forces are weak, as a molecule gets larger, it has more intermolecular forces, therefore it has a stronger force of attraction that requires more energy to break.
60
Why do simple molecular substances not conduct electricity? (2 marks)
In order for the molecules to conduct electricity, they need to have free electrons. Furthermore, the molecules themselves have no overall electric charge.
61
What are giant covalent structures arranged in? What are they made up of?
They are generally arranged in regular repeating lattices | They have large numbers of non-metal atoms joined together by covalent bonds.
62
Why do giant covalent structures have high melting and boiling points?
You would need to break the strong covalent bonds in order to melt them
63
Why do the giant covalent structures not conduct electricity?
They do not contain any charged particles
64
What is a diatomic molecule?
It is a molecule that consists of two atoms covalently bonded together
65
Why do all halogens exist as diatomic molecules?
Each halogen has one electron less than the nearest noble gas so therefore it has a tendency to share its electrons with another halogen
66
What are the trends for halogens as you go down the group? (properties)
Melting and boiling point increases Get darker in colour Reactivity decreases
67
Why does reactivity of halogens decrease as you go down the group?
As the atom gets bigger, the outermost shell gets further away from the positive nucleus. This means the attractive force needed to gain an electron gets weaker. If a halogen can't attract an electron to complete its outer shell, it can not react.
68
What do you call a halogen that gains an electron to form a 1- ion?
A halide | e.g. bromide
69
Show the displacement reaction between a halogen? | Cl₂ + 2KBr ---> ..... + ....
Cl₂ + 2KBr ---> Br₂ + 2KCl
70
What happens in a displacement reaction between halogens?
More reactive halogen will displace the less reactive halogen
71
What happens when you add chlorine to colourless potassium bromide?
The solution becomes orange as bromine is formed
72
What happens when you add chlorine to colourless potassium iodide?
The solution becomes brown as iodine is formed
73
What happens when you add bromine to colourless potassium iodide?
The solution becomes brown as iodine is formed
74
What are the properties of noble gases? (3 marks)
They are monatomic (they exist as individual atoms) They are colourless, non-flammable gases at room temperature They have low melting and boiling points The noble gases are very stable and the most unreactive (inert)
75
Why are noble gases unreactive and inert?
They have full outer shells and therefore are very stable
76
Why do the boiling points increase in noble gases as you go down the group? (3 marks)
The boiling point increases down the group due to an increase in the relative atomic mass. This leads to an increase in intermolecular forces between atoms, increasing the amount of energy needed to overcome these forces to change state.
77
Why do group 0 elements have low densities?
This is because the individual atoms are widely spaced apart. The densities increase as you go down the group.
78
What are metal chlorides?
They are white solids.
79
What happens when you dissolve metal chlorides in water?
they dissolve readily in water to form colourless solutions
80
What are the first 4 halogen elements at room temperature?
Fluorine is a pale yellow gas Chlorine is a poisonous green gas Bromine is a toxic red-brown liquid Iodine is a dark grey solid which gives off a purple vapour when heated
81
How was the problem of some elements not fitting the pattern when arranged by atomic weights in Mendeleev’s table solved?
Table actually arranged by atomic number | Discovery of isotopes
82
What is the Haber process used to make?
Ammonia
83
What are the properties of the halogens? (4 marks)
They’re toxic Low melting and boiling points Poor conductors of heat and electricity
84
How do halogen molecules differ from other groups?
They exist in pairs as diatomic molecules
85
Describe what happened when different halogens are present in the reaction of a metal?
A more reactive halogen will displace a less reactive halogen from the aqueous solution of its salt
86
What colour compound is produced from copper sulphate ions?
Blue
87
Why did Medeleev leave gaps in his periodic table?
As the elements did not fit the pattern
88
What are the compounds formed from only non-metals consist of particles called?
molecules
89
Explain why an atom has no overall charge. Use the relative electrical charges of sub-atomic particles in your explanation.
The charge for an electron is (1-) whereas the charge for a proton is (1+). And the number of electrons is equal to the number of protons.
90
Explain one way in which Mendeleev improved Newlands’ periodic table
He left gaps for undiscovered elements so that the elements would remain in their proper groups
91
Why do Transition elements have similar properties? Explain why, in terms of electronic structure.
Transition elements have a similar number of outer electrons as their inner shells are being filled.
92
Why was Mendeleev leaving gaps for undiscovered elements helpful?
He predicted the properties of elements so when elements were discovered they matched his predictions
93
Explain why the early periodic tables placed iodine before tellurium, but later Mendeleev placed tellurium before iodine.
Early periodic tables were arranged in order of their atomic weights Iodine has a lower atomic weight than tellurium Mendeleev placed iodine with elements with similar properties

Chemistry (8 decks)

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