Atomic Theory Flashcards
(95 cards)
0
Q
What are physical properties called?
A
Macroscopic properties
1
Q
What is matter?
A
Matter is anything made up of atoms and molecules. Matter is anything that has mass.
Matter is everything we….
- touch
- hear
- smell
- see
- can’t see
- feel
2
Q
What are chemical properties called?
A
Microscopic properties
3
Q
What are the characteristics of macroscopic properties?
A
- Physical or Macroscopic properties are observable properties.
- We use our senses to detect them.
4
Q
What are the characteristics of microscopic properties?
A
- Chemical or Microscopic properties are often unobservable properties but can be studied by carrying out experiments.
- These properties involve the arrangement of atoms & molecules and the way they are bonded together.
5
Q
What is the kinetic theory of matter (the particle theory)?
A
- Matter is made up of tiny, invisible moving particles
- Particles of different substances have different sizes
- Lighter particles move faster than heavier particles
- As the temperature rises, the particles move faster
- In a solid, the particles are very close together and vibrate in fixed positions
- In a liquid, the particles are a little further apart. They have more energy and they can move around each other
- In a gas, the particles are very far apart. They move rapidly and randomly in all the space that surrounds them.
- The particles might be atoms, molecules or ions.
6
Q
What are the properties of a solid?
A
– have a definite shape and volume
- are held tightly and packed fairly close together they are strongly attracted to each other
- are in fixed positions but they do vibrate
7
Q
What are the properties of a liquid?
A
– have a definite volume but an indefinite shape
- are fairly close together with some attraction between them
- are able to move around in all directions but movement is limited by attractions between particles
8
Q
What are the properties of a gas?
A
– have an indefinite shape and volume
- have little attraction between them and are widely spaced out
- are free to move in all directions and collide with each other and with the walls of a container
9
Q
What are some solids called eg rubber? And why?
A
Some solids (eg. rubber) are called AMORPHOUS because they do not have a regular structure.
10
Q
What is meant by melting point and what does it indicate about a substance?
A
The temperature at which a solid melts
The melting point of a solid indicates how strongly particles are held together.
Substances with high melting points have strong forces between their particles
11
Q
What is meant by freezing point?
A
The temperature at which a liquid solidifies
12
Q
What is meant by boiling point?
A
The temperature at which evaporation begins to occur within the bulk of the liquid
13
Q
What is meant by condensation point?
A
The temperature when the vapour cools back into a liquid
14
Q
What are volatile liquids? What is different about their particles?
A
Volatile liquids are those which evaporate at low temperatures (eg Petrol)
These have weak forces between their particles than substances with higher boiling points
15
Q
How can matter be changed from state to state?
A
By varying the temperature and sometimes the pressure.
16
Q
What are crystalline solids?
A
They are solids which have a fixed shape.
17
Q
What is the change that occurs from a solid to a liquid?
A
Melting
18
Q
What is the change that occurs from a liquid to a gas?
A
Evaporation
19
Q
What is the change that occurs from a liquid to a solid?
A
Freezing/solidification
20
Q
What is the change that occurs from a gas to a liquid?
A
Condensation
21
Q
What is the change that occurs from a solid to a gas?
A
Sublimation
22
Q
What is the change that occurs from a gas to a solid?
A
Sublimation
23
Q
What do atoms of an element have in common?
A
All contain the same number of protons.
Are neutral, as the number of protons is equal to the number of electrons.
24
What were the goals of alchemy?
1. The transmutation of metals
2. The creation of an elixir that would prolong life indefinitely
3. The transmutation of human life
4. To search for the Philosopher's Stone (manipulate time)
25
What is the scientific method?
Backing up theories with experimental evidence.
1. Observe something happening
2. Develop a hypothesis about why it happens
3. Design experiments to test the hypothesis
4. Predict what will happen in the experiments
5. Perform the experiments and observe what actually happens
6. Modify the hypothesis if predictions were wrong
Repeat from step 3.
26
What is the order of the scientists who discovered parts of the atomic theory?
```
Democritus
Aristotle
John Dalton
J.J. Thomson
Ernest Rutherford
Niels Bohr
James Chadwick
```
27
What did Democritus propose?
All matter is made up of tiny indivisible particles called atoms.
28
What did Aristotle propose?
All matter water made up of four elements; earth, fire, water and air.
29
What did John Dalton propose? How did he come about with this theory and why was it different to scientists' discoveries before his time?
All matter was made up of atoms.
Atoms of the same element are identical and have the same mass.
Atoms of different elements have different masses.
Atoms could not be created or destroyed.
Atoms cannot be changed into other atoms.
Atoms combine together in simple ratios to form molecules.
He proposed this based on experimentation and observations, not on pure reason as other scientists' before his time did.
30
What did J.J. Thomson propose?
That atoms consisted of a positively charge sphere with electrons embedded into it. The Plum Pudding Model.
31
What did J.J. Thomson discover and how?
He discover a negatively charged particle that is 2000 times smaller than a hydrogen atom.
Atoms are divisible: subatomic particles.
He discovered this by his experimentation with his Cathode Ray: that the electrons that made up the cathode rays could be deflected by magnets or electrically charged plates.
32
What did Ernest Rutherford propose?
That atoms were mainly empty space.
Each atom consisted of positive particles, which he called protons.
Protons are found in the core of the atom, which he called the nucleus.
Electrons move around the nucleus in random orbits.
33
What did Ernest Rutherford discover and how?
He discovered the protons, the nucleus, electrons have random orbits and that an atom is mostly empty space.
He discovered this by conducting the Gold Foil Experiment.
He shit alpha particles at a thin sheet of gold foil and found that some of the beams passed straight through and other deflected.
This bought him to the conclusion that if the negative beams were being deflected only sometimes, there must be a place concentrated to a positive charge that was deflecting the beam.
34
What did Niels Bohr propose?
The shell model.
That electrons have fixed orbits/ energy levels/ quantum levels, which he called shells.
Electrons closer to the nucleus are of lower energy than those further out.
He also proposed the theory of quantum energy and measured the wavelengths of the different energy levels by using a mathematical formula.
35
What is a quantum of energy or photon?
It is an emission of light that is the result of an electron gaining enough energy to move to a higher energy level and, when falling back to its ground state position, emitting the photon.
36
What did James Chadwick propose?
He discovered the neutron in an atom.
The third subatomic particle.
Same mass as a proton but no charge.
K,L,M,N shells
37
What did James Chadwick discover and how?
The neutron.
He bombarded a sample of beryllium with alpha particles and found a ray was given off.
The particles that made up the ray were not deflected by a magnetic or electrical field: which indicated that they carried no charge.
38
What did Erwin Schrödinger propose?
The quantum mechanical model.
No predetermined paths for electrons, but they move around in regions of space called orbitals.
He proposed the theory that were what sub-shells within the shells of an atom.
They have similar amounts of energy.
These sub-shells have characteristic shapes and different amounts of energy.
s, p, d, f, g orbitals
39
What does s, p, d and f stand for? And how many electrons can each hold?
```
s= sharp = 2
p= principal = 6
d= diffuse = 10
f= fine = 14
```
40
List the order of the sub-shells.
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 ......
41
What is the Pauli Exclusion Principle?
Each orbital cannot accommodate more than 2 electrons.
42
What is Hund's Rule?
When electrons occupy orbitals of equal energy, one electron enters each orbital until they all contain one electron.
43
A=? And Z=?
A=mass number
| Z=atomic number
44
What is an ion?
Ions are atoms that have lost or gained electrons and therefore carry a positive or negative electric charge.
This happens when a neutral atom loses or gains electrons to satisfy the need of having a full valance shell.
45
What are isotopes?
Isotopes are atoms of the same element which have the same atomic number (protons), but different mass numbers, due to having a different number of neutrons in their nucleus.
Eg: Carbon = C 12 6
C 14 6
46
What is an element?
An element is a pure substance containing atoms all of which have the same number of protons.
Eg: Hydrogen, Lithium, Gold, Aluminium
47
What is a molecule?
A molecule is a group of atoms (same type or combination) chemically bonded together.
Eg: one molecule of hydrogen contains two hydrogen atoms- diatomic molecule.
48
What is a compound?
A compound is a pure substance in which different elements are chemically combined in fixed proportion by mass.
Can be separated (decomposed/broken down) through chemical reactions.
Eg: water, sugar
49
What is a mixture?
A mixture is two or more substances are combined without them chemically reacting together. It is simply a substance mixed in with another substance.
A mixture can be easily separated.
Eg: salt and sand
50
What is meant by ground state?
The lowest energy level for an electron.
51
What is meant by excited state?
When an electron absorbs energy it becomes excited and jumps to a higher energy level. Unstable state.
52
What is the atomic emission spectra?
Emission spectrum refers to the range of wavelengths emitted by an atom stimulated by either heat or electric current.
Emission spectra is unique to each element.
53
What happens to the energy levels of an atoms as you move further away from the nucleus?
They get closer together.
| They are concentric and converging.
54
When the number of shells reaches infinity what happens?
It makes an ion because it rips the electron off the atom.
55
What is the electronic configuration of fluorine? 9e-
1s2 2s2 2p5
56
What is the electronic configuration of copper? 29e-
1s2 2s2 2p6 3s2 3p6 3d10 4s1
57
What is the electronic configuration of chromium? 24e-
1s2 2s2 2p6 3s2 3p6 3d5 4s1
58
Define abundance.
How much (%) there is of a certain isotope in a natural occurring element.
59
Define Relative Isotopic Mass (RIM).
The mass of a single isotope compared with the mass of the Carbon-12 isotope, measured on the relative atomic mass scale.
60
Define Relative Atomic Mass (Ar).
The weighted average of the relative isotopic masses of an element.
61
What is the Relative Atomic Mass equation?
Ar= (relative abundance1 x RIM1) + (relative abundance2 x RIM2) + (relative abundance3 x RIM3)....
———————————————————————————————
100
62
What is Relative Molecular Mass?
It is the sum of the relative atomic masses of elements in a molecular formula.
Eg: covalent substances (O2 and H2O)
63
What is the Relative Molecular Mass formula?
Mr(z)= 2 x Ar(z)...
Eg:
Mr(H2O)= 2 x Ar(H) + Ar(O)
= 2 x 1.01 + 16.00
= 18.02
64
What is Relative Formula Mass (Fr)?
It is the sum of the relative atomic masses of elements in a non-molecular formula.
Eg: ionic substances (KCl)
65
What is Relative Formula Mass (Fr) equation?
Eg: KCl
Fr(KCl)= Ar(K) + Ar(Cl)
= 39.10 + 35.45
= 74.55
66
Who discovered isotopes and when?
Frederick Soddy in 1910
67
What is a mass spectrometer?
It is an analytical technique for the determination of the elemental composition of a sample or molecule.
It shows information about the relative atomic mass and percentage abundance of each isotope.
68
What are the uses of a mass spectrometer?
Identifying unknown substances
Identifying isotopes in an element
Determining the relative isotopic mass of a particular atom.
69
Why is relative isotopic mass used rather than the true masses of elements?
Because otherwise the masses will be extremely small.
70
What is the order of the scientists who contributed to the discovery of the periodic table?
```
Antoine Lavoisier
Johann Dobereiner
William Odling
John Newlands
Lothar Meyer
Dimitri Mendeleev
William Ramsay
Henry Moseley
Gland Seaborg
```
71
What did Johann Döbereiner proposed about the periodic table?
Johann Döbereiner, grouped sets of three chemically similar elements into ‘triads’.
He showed that if the three chemicals are placed in order of atomic mass, the middle element was the average of the other two.
72
What did John Newlands proposed about the periodic table?
John Newlands, proposed the ‘law of octaves’.
When the elements were arranged in order of increasing atomic mass, elements of similar chemical properties occurred at intervals of eight.
73
What did Lothar Meyer proposed about the periodic table?
Lothar Meyer, showed a periodic repetition of physical properties, such as boiling points and atomic volumes, with respect to atomic mass.
74
What did Dimitri Mendeleev proposed about the periodic table?
Dmitri Mendeleev, also proposed that the properties of elements are a periodic function of atomic mass.
He arranged the known elements at the time in a ‘periodic table’ with gaps for elements that he considered were yet to be discovered.
75
What did William Ramsay proposed about the periodic table?
William Ramsay’s discovered the noble gases or inert gases added a new column to the periodic table.
76
What did Henry Moseley proposed about the periodic table?
Atomic number.
Henry Moseley’s discovered quantities of positive charges (later identified by Ernest Rutherford as protons) inside the nucleus led to the notion of atomic numbers.
The organisation of elements on the periodic table was changed from an order of increasing atomic weights to increasing atomic numbers as a result of this discovery.
77
What did Glenn Seaborg proposed about the periodic table?
Glenn Seaborg was an American nuclear scientist who was involved in the synthesis of elements 94 to 102. To date, elements up to 112 have been made; the last few elements are extremely unstable.
78
What is wrong with elements after uranium in the periodic table?
Elements after uranium (atomic number 92) are artificially synthesised and radioactive. They are known as the transuranium elements.
79
What are group 1 elements called?
Alkali metals
80
What are group 2 elements called?
Alkaline earth metals
81
What are group 17 elements called?
Halogens
82
What are group 18 elements called?
Noble gases (inert)
83
The period number tells us....
The number of shells in the atom.
84
The group number tells us.....
The number of valance electrons in the atom.
85
What are the trends down a group?
```
Metallic character- increases
Melting point- decreases for groups 1 to 5 and increases for groups 15 to 18
Reactivity- increases
Atomic size- increases
Electronegativity- decreases
Ionisation energy- decreases
Oxidating strength- decreases
Reducing strength- increases
```
86
What are the trends across a period?
Metallic character- decreases
Melting point- generally increases then decreases
Reactivity- lowest in middle, increases either end
Atomic size- decreases
Electronegativity- increases
Ionisation energy- increases
Oxidation strength- increases
Reducing strength- decreases
87
What is oxidising strength?
It is how readily an element gains electrons.
88
What is reducing strength?
It is how readily an element loses electrons.
89
Why does ionisation energy decrease as you go down a group?
Because there are more and more shells the further down you go, the valance shells are further away from the nucleus meaning there is less electrostatic attraction which means there is low energy needed to remove it.
90
Why does ionisation energy increase as you go across a period?
Because the shell number remains constant across a period, but the nucleus is getting bigger as it is gaining protons and neutrons and more electrons are being added to the valance shell which means the valance shell is more stable (full) and it takes more energy to remove a valance electron.
91
What is core charge?
It is the effective charge of the nucleus that is experienced by the valance electrons.
92
What is the equation for core charge?
Core charge= atomic number - number of inner shell electrons
93
What is Electronegativity?
It is the electron attracting power of an atom.
94
What is ionisation energy?
The energy it takes for an atom to become an ion.
