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Atomic Structure - Coggle Diagram
Atomic Structure
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Arrangement of electrons
1913 - Niels Bohr - Rutherford idea of a cloud of electrons would cause the atom to collapse, so Bohr came up with the idea of electrons in a fixed orbit.
Energy level shells
1st - 1s
2nd - 2s, 2p
3rd - 3s, 3p, 3d
4th - 4s, 4p, 4d
Example:
Na has 11 electrons
GCSE: 2, 8, 1
A-level: 1s², 2s², 3s¹
Chromium and Copper are the only elements where this is different.
Cr = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹
Cu = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹
When transition metals lose electrons to become ions, they lose their 4s before their 3rd.
Fe = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²
Fe³+ = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵
Isotopes - atoms with the same number of protons but a different number of neutrons, same chemical properties but different physical properties.
Ar
Relative atomic mass - the average mass of an atom of a element on a scale where an atom of carbon-12 is exactly 12, shown in the periodic table.
Relative isotopic mass - the mass of an atom of an isotope of an element on a scale where an atom of carbon-12 is exactly 12. (If asked for mass number of an isotope - total number of protons and neutrons)
Mr
Relative molecular mass - the average mass of a molecule on a scale where an atom of carbon-12 is exactly 12. (To calculate, add up the RAM values of all the atoms in the molecule)
Relative formula mass - the average mass of a formula unit on a scale where one atom of carbon-12 is exactly 12. Used for ionic of giant covalent compounds. (To calculate, add up the RAMs if all the ions in the formula unit)
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Ionisation energies
1st ionisation energies
• The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
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Strength of attraction depends on:
• Number of protons (nuclear charge)
• Amount of 'shielding' present by inner electrons
• Distance between nucleus and outer electron (atomic radius)
• You can figure out the atoms group from energy needed to remove outer electrons shell, when big jump it means the next electron is from an inner shell.
2nd ionisation energies
• The second ionisation energy is the energy needed to remove 1 electron from each ion in 1 mole of gaseous ions to form 1 mole of gaseous 2+ ions.
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