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85 Cards in this Set
- Front
- Back
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How many natural elements are there? |
Approx. 92 |
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What is the actual mass and charge of a proton, neutron and electron? |
Mass p+ - 1.67x10^-27 kg Charge p+ - +1.6x10^-19 C Mass neutron - 1.67x10^-27 kg Charge neutron - 0 C Mass e- - (1.67x10^-27 kg) x 5x10^-4 Charge e- - -1.6x10^-19 C |
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What is the relative mass and charge of a proton, neutron and electron? |
Mass p+ - 1 Charge p+ - +1 Mass neutron - 1 Charge neutron - 0 Mass e- - 5x10^-4 Charge e- - -1 |
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What is the size of the nucleus compared to the atom? |
Nucleus is between 10,000 and 100,000 times smaller than an atom |
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What are ions? |
Atoms which have lost or gained electrons |
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What are isotopes? |
Atoms of an element with a different number of neutrons |
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How are isotopes similar and different to other isotopes of the same element? |
Same chemical properties, different physical properties |
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What is Relative Atomic Mass? |
RAM is the average mass of all the isotopes of an element compared to the mass of 1/12 of carbon-12 |
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How are electrons arranged? |
In energy levels (shells) around the nucleus |
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What is the max number of electrons in each main energy level sometimes called? |
n |
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What is the main energy level also called? |
Principle quantum number |
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What is the max number of e- in a shell? |
2n^2: 1 = 2 2 = 8 3 = 18 4 = 32 5 = 50 |
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How is frequency proportional to wavelength? |
Indirectly proportional (frequency ∝ 1/wavelength) |
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How is frequency proportional to energy? |
Directly proportional (frequency ∝ energy) |
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What are particles of EM radiation sometimes called? |
Photons |
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What happens to hydrogen gas when subjected to high voltage at low pressure? |
It glows pink |
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What can glowing gasses be looked at through? |
A spectroscope, which contains a diffraction gradient and separates the various wavelengths of light emitted |
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What is an emission spectrum? |
A spectrum of the electromagnetic radiation emitted by a source |
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Describe a line spectrum |
Sharp, bright lines on a dark background |
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Describe a continuous spectrum |
All colours merging into each other |
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How is an emission spectrum formed? |
By passing an electron discharge through a gas, causing it to be promoted to a higher energy level |
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Define excited state |
When the e- is in a higher energy level than the ground state |
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What will happen to the e- at this energy level? |
It is unstable so it will fall to a lower energy level, and a photon of light is emitted |
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What can EM waves travel through? |
Space or matter |
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What is the equation for speed? |
c = λ x f speed = wavelength x frequency |
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What is the equation for energy? |
E = h x f energy = Plank's constant (js) x frequency (s^-1) |
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What three things may a spectrum exhibit? |
- a continuum - an emission spectrum (when e- emits photons/loses energy) - an absorption spectrum (when e- gains photons/gains energy) |
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What two types of continuous spectrum are there? |
Emission and absorption (both have all possible colours) |
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Where are emission spectrum produced? |
In thin gases in which the atoms don't experience many collisions - the emission lines are correspondent to the energies that are emitted |
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When does a continuous spectrum occur? |
When the gas pressures are higher |
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Which three forms of EM radiation are seen in hydrogen spectrum? |
IR, UV and visible light |
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What part of the EM spectrum will be produced from a transition from n = ∞ to n = 2? |
Lines in the visible part of the spectrum |
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What part of the EM spectrum will be produced from a transition from n = ∞ to n = 1? |
Lines in UV part of the spectrum |
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What part of the EM spectrum will be produced from a transition from n = ∞ to n ≥ 3? |
Lines in the IR part of the spectrum |
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How do the series in each region of the emission spectrum change? |
All consist of lines, but lines get closer at higher frequency |
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How do we know that n = 1 requires the most energy to reach? |
As transition down to n = 1 produces lines in UV region, which have highest energy in EM spectrum |
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Why is the atomic emission spectrum of hydrogen simple? |
As it only contains 1e- |
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Why do He+ and Li2+ have similar spectrum? |
As both are single-electron ions, but will be slightly different because of proton and neutron number |
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What happens as energy gets higher? |
Lines in an emission spectrum get closer |
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What is the convergence limit? |
When the lines in an emission spectrum merge to form a continuum |
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What happens to electrons beyond the convergence limit? |
e- can have any energy and so are free from the influence of the nucleus |
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What are main energy levels made up of? |
Sub-energy levels (sub-shells) |
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Which sub-levels does the 1st main energy level have? |
1s |
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Which sub-levels does the 2nd main energy level have? |
2s, 2p |
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Which sub-levels does the 3rd main energy level have? |
3s, 3p, 3d |
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Which sub-levels does the 4th main energy level have? |
4s, 4p, 4d, 4f |
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How many electrons can each sub-level hold? |
- s = 2 - p = 6 - d = 10 - f = 14 |
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What is the order of sub-levels? |
s < p < d < f |
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What is the one reversal in order of sub-levels? |
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 4d < 4f |
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What does the Aufbau principle dictate? |
The process of working out the e- configuration in an atom |
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What is the e- configuration of Na (11e-)? |
1s2 2s2 2p6 3s1 |
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In what other way can the e- configuration of Na be written? |
[Ne]3s1 |
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How can the e- config. of Fe be written? |
[Ar]4s2 3d6 |
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What do electrons occupy in atoms? |
Orbitals |
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What is an orbital? |
A region of space in which there is a high probability of finding an e- |
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How many e-s can an orbital contain? |
A max of 2 |
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What types of orbitals are there? |
s, p, d, f |
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Which orbitals does the first shell consist of? |
1 1s orbital, which takes up the entire 1s sub-level |
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What is electron density? |
The likelihood of finding an e- in the area |
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How is electron density represented? |
The darker the colour, the higher probability of finding and e- there |
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What does the second main energy level contain? |
2s and 2p sub level |
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What is the 2p sub-level made of? |
3x 2p orbitals |
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What shape are s orbitals? |
Spherical |
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What shape are p orbitals? |
'dumb-bell' shape |
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How are the three 2p orbitals arranged? |
They lie at 90 degrees of eachother |
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What are the 3 2p orbitals called? |
Px, Py and Pz |
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Do orbital energy levels differ? |
Within any sub-shell, all the orbitals are degenerate (have the same energy levels) |
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How many orbitals are there in each main energy level? |
> 1 - 1xs > 2 - 1xs, 3xp > 3 - 1xs, 3xp, 5xd > 4 - 1xs, 3xp, 5xd, 7xf |
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What other property do e- have (apart from moving around within an orbital)? |
Spin |
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What is the first rule one must consider before e- are put in orbitals? |
Pauli exclusion principle: Max no. of e- in an orbital is 2. If there are 2 e- in an orbital, they must have opposite spin |
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What is the second rule one must consider before e- are put in orbitals? |
Hund's rule: e- fill orbitals of the same energy (degenerate orbitals) so as to give the max. no. of e- with the same spin. |
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How would 3 e- in the orbitals in the 2p sub-level be arranged? |
Px Py Pz 1 1 1 |
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What does knowing the frequency of light emitted at the convergence limit enable us to work out? |
The ionisation energy of the atom |
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What is the ionisation energy? |
The energy required to ionise an atom: M(g) --> M+(g) + e- |
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Define ionisation energy |
The min. energy required to remove one e- from a mole of a gaseous atom |
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What does the frequency at the convergence limit in the Lyman series represent? |
The amount of energy given out when an e- falls from outside the atom to level 1 |
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What is the wave-particle duality? |
Light, and other forms of EM radiation, exhibit properties of both waves and particles |
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What can E = hv be used to work out? |
The difference in energy between various levels in the hydrogen atom |
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With what two equations can the energy of a photon be related to its wavelength? |
c = vλ and E = hv |
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How can the ionisation energy of hydrogen be obtained? |
From the study of a series of lines when the e- falls back to the ground state energy level (only the Lyman series) |
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What is the second ionisation energy? |
The ionisation energy for the process: M+ (g) --> M2+ (g) + e- |
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What is the nth ionisation energy? |
The ionisation energy required for the process: M(n-1) (g) --> M(n)+ (g) + e- |
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Which e- is removed first? |
The highest energy e- |
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What is the first reason as to why the 2nd ionisation energy is always higher than the first? |
Once an e- has been removed from an atom, it becomes a cation. A cation attracts e- more strongly than a neutral atom. More energy is therefore required to remove the 2nd e- |
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What is the second reason as to why the 2nd ionisation energy is always higher than the first? |
Once an e- has been removed from an atom, there is less repulsion between the remaining e-. They are therefore pulled in closer to the nucleus and are more strongly attracted and more difficult to move |
