Atomic Structure
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- Created by: Lotto65
- Created on: 12-05-18 19:42
Which element has no neutrons?
Hydrogen
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What are nucleons?
Protons and neutrons
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Where is all the mass of an atom concentrated?
In the nucleus
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What determines the volume of an atom?
The electrons
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What is unique for elements?
Atomic number
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Who discovered electrons?
J.J Thompson
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Number of electrons =
Number of protons
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Why is atomic number related to protons when they equal electrons?
Electrons are lost or gained when ions are formed and you can have isoelectric atoms
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Which value is normally at the top on periodic tables?
Mass number
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What does the A mean in a periodic table?
Mass number
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What does the Z mean in a periodic table?
Atomic number
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What is different between isotopes?
Number of neutrons and therefore the mass number
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Isotopes have the same...
Chemical properties (electrons are the same)
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Isotopes have different...
Physical properties (melting and boiling points)
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Why do isotopes have different physical properties?
Different masses mean they move at different speeds
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Why do relative atomic masses exist?
Averages of isotopes in a naturally occurring sample
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What are relative atomic masses relative to?
Carbon -12
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When calculating the relative atomic mass of an element, what must you remember to do?
Divide by 100
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What is the equation for calculating abundance of heavier isotope?
Ar - mass number of lighter isotope all divided by the difference between the isotopes and then multiplied by 100
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What does a mass spectrometer do?
Measures the proportion of each isotope in a sample
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The area under each peak in a mass spectrum is proportional to what?
The abundance of that isotope (number of atoms)
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The lowest energy level is...
The one closest to the nucleus
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What is the principal quantum number?
The main energy level
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How many electrons fill the fourth energy level?
32
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In elements up to an atomic number of 20, what happens when 8 electrons fill the third energy level?
Go to fourth one
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What speed do electromagnetic waves travel at in a vacuum?
Speed of light which is 3.0 x 10^-8
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If all electromagnetic waves travel at the same speed in a vacuum, is there frequency, wavelength and energy the same?
No
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What does the hydrogen atom spectrum prove?
There are energy levels in atoms
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How is the hydrogen emission spectrum seen?
Subject hydrogen to low pressure but high voltage so it glows pink. Look at it through a spectroscope containing a diffraction grating to separate wavelengths
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What two types of spectrums are there?
A line spectrum (certain frequencies/ wavelengths of light) and a continuous spectrum (all wavelengths/ frequencies of light)
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At a higher frequency, what happens to the lines in a hydrogen line spectrum?
Get closer together
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What is a photon?
A particle of electromagnetic radiation
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What is the lowest energy level sometimes called?
The ground state
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How is a hydrogen emission spectrum created?
Pass electric discharge through gas and electrons are promoted to higher energy levels. This is unstable so they fall back down to a lower energy level and emit a photon of light that contributes to a line
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Why do electrons fall and not stay at a high energy level?
They are only allowed to have a certain amount of energy in an atom and they became unstable
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The visible region in the hydrogen spectrum is caused by the fall of electrons to which level?
2
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The UV region in the hydrogen spectrum is caused by the fall to which level?
1
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Which energy difference is bigger in the hydrogen emission spectrum?
Between a level and level 1 in comparison to level 2
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Do Li2+ and He+ have the same emission spectra as hydrogen because they are isoelectric?
Similar but not identical because of a different number of protons which influences electron energy levels
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At what point do the lines converge in a hydrogen emission spectrum?
At the convergence limit
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What can we deduce about the electron beyond the continuum/ convergence limit?
It is no longer a part of the atom and can have any energy
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Where is the 4s sublevel in terms of energy?
Between 3p and 3d sublevels
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Why do electrons fill from the lowest energy level?
Give the lowest possible potential energy
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How can you work out the last subshell in an element?
Look at the period it is in (maximum energy level) and then which block it is in. How many elements into that block is the number of electrons in that subshell
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All elements in the same group have the same what?
Number of valence electrons and final subshell and number of electrons in that subshell (might be on different energy levels though)
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Which part of the periodic table is the p block?
Right side
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Which element in the p block actually has no final p subshell?
Helium
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How many p orbitals are there per energy level?
3
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Is the 2s orbital bigger or smaller than the 1s orbital?
Bigger
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p orbitals are...
Degenerate (same energy)
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How many f orbitals are there in one energy level?
7
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What is the Pauli exclusion principle?
A maximum of two electrons can be in an orbital. If there are 2 electrons in an orbital, they must have opposite spin
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What is Hund's rule?
Electrons fill orbitals of the same energy so there is a maximum number of electrons with the same spin
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What is similar about chromium and copper but makes them different to the laws of electron filling?
Have one electron in the 4s subshell/ orbital
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How many electrons does copper have in its 3d subshell?
10
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How many electrons does chromium have in its 3d subshell?
5
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Why does Hund's rule exist/ work?
Makes atom more stable and a lower energy situation
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What can be worked out if you know the frequency of light emitted at the convergence limit?
Ionisation energy
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What state does ionisation energy involve?
Gaseous
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What is wave-particle duality?
Electromagnetic radiation has properties of waves and particles
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What is h in an equation?
Planck's constant
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What is v in the energy of waves equation?
Frequency NOT speed
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What is c in energy equations?
Speed of light
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How do you calculate the ionisation energy from the energy to remove one electron from one atom?
Multiply by avagadro's constant
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Which electrons are removed first in atoms?
Ones from the highest energy level/ subshell
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Why is the second ionisation energy higher than the first?
Less repulsion between remaining electrons and are pulled closer to nucleus. More attraction to nucleus. Also a positive ion is created which attracts electrons more than a neutral atom so more energy required to remove an electron
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How do you calculate effective nuclear charge?
Number of protons in the nucleus - number of electrons shielding the outer electron
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Do electrons in the same shell shield each other?
No
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Why might ionisation energies for electrons in the same energy level not increase evenly?
Different subshells of different energies
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What provides evidence for subshells?
Ionisation energies for electrons in the same energy level are not evenly spaced
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Same period means what for shielding...
No real change in shielding across a period
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What are the two exceptions to the ionisation energy rule?
Boron has a lower ionisation energy than beryllium despite that it has a higher nuclear charge. Oxygen has a lower ionisation energy than nitrogen
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Why does boron have a lower ionisation energy than beryllium despite that it has a higher nuclear charge?
Boron's outer electrons are in a higher 2p subshell compared to beryllium in a 2s subshell so require less energy to remove
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Are electrons in the same orbital harder or easier to remove than an electron on its own?
Easier due to repulsion from the other electron
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Why does oxygen have a lower ionisation energy than nitrogen?
Oxygen and nitrogen both have electrons in every 2p orbital but nitrogen has only one in each while oxygen has an extra electron in one orbital giving a pair. Repulsion means it is easier to remove
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In transition metals, despite than 3d subshells have a higher energy than 4s electrons, where are electrons removed from first?
4s subshell
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Other cards in this set
Card 2
Front
What are nucleons?
Back
Protons and neutrons
Card 3
Front
Where is all the mass of an atom concentrated?
Back
Card 4
Front
What determines the volume of an atom?
Back
Card 5
Front
What is unique for elements?
Back
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