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Expanding the Theory of the Atom
Chapter 7 Expanding the Theory of the Atom
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Democritus and Leucippus
Matter is made up of indivisible particles Dalton - one type of atom for each element Page 231
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Thomson’s Model Discovered electrons “Plum-Pudding” model
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Rutherford’s Model Discovered the nucleus Electrons moved around
Mostly empty space
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Bohr’s Model Electrons move in circular orbits at different levels. Amounts of energy separate one level from another.
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Bohr’s Model Nucleus Electron Orbit Energy Levels
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} Bohr’s Model Further away from the nucleus means more energy. Fifth
There is no “in between” energy Energy Levels Fifth Fourth Third Increasing energy Second First Nucleus
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The Quantum Mechanical Model
Energy is quantized. A quanta is the amount of energy needed to move from one energy level to another.
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The Quantum Mechanical Model
Energy levels for electrons. Orbits are not circular. It can only tell us the probability of finding an electron a certain distance from the nucleus.
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The Quantum Mechanical Model
Electron cloud Area where there is a chance of finding an electron.
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Atomic Orbitals Principal Quantum Number (n) = the energy level of the electron. These are called atomic orbitals Regions where there is a high probability of finding an electron.
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S orbitals Starts at first energy level Spherical shaped
Each s orbital can hold only 2 electrons Called the 1s, 2s, 3s, etc. orbitals.
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P orbitals Start at the second energy level 3 different directions
3 different shapes Each can hold 2 electrons
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P Orbitals
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D orbitals Start at the third energy level 5 different shapes
Each can hold 2 electrons
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F orbitals Start at the fourth energy level
Have seven different shapes 2 electrons per shape
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F orbitals
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Summary # of shapes Max electrons Starts at energy level s 1 2 1 p 3 6
d 5 10 3 7 14 4 f
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Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p 3s 2p
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By Energy Level First Energy Level only s orbital only 2 electrons 1s2
Second Energy Level s and p orbitals are available 2 in s, 6 in p 2s22p6 8 total electrons
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By Energy Level Third energy level s, p, and d orbitals
2 in s, 6 in p, and 10 in d 3s23p63d10 18 total electrons Fourth energy level s,p,d, and f orbitals 2 in s, 6 in p, 10 in d, ahd 14 in f 4s24p64d104f14 32 total electrons
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Electron Configurations
The way electrons are arranged in atoms. Aufbau principle - electrons enter the lowest energy first. Overlap of orbitals of different energies.
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Electron Configuration
Phosphorus: - Need to account for 15 electrons
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Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
The first two electrons go into the 1s orbital only 13 more
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Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
The next electrons go into the 2s orbital only 11 more
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Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
The next electrons go into the 2p orbital
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Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p
The next electrons go into the 3s orbital only 3 more
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Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s
The last three electrons go into the 3p orbitals. They each go into separate shapes 3 unpaired electrons 1s22s22p63s23p3
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The easy way to remember
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f
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Fill from the bottom up following the arrows
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 4 electrons
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Fill from the bottom up following the arrows
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s2 12 electrons
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Fill from the bottom up following the arrows
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s2 3p6 4s2 20 electrons
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Fill from the bottom up following the arrows
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 38 electrons
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Fill from the bottom up following the arrows
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 56 electrons
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Fill from the bottom up following the arrows
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 88 electrons
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Fill from the bottom up following the arrows
2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6 108 electrons
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Exceptions to Electron Configuration
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Orbitals fill in order Lowest energy to higher energy.
Half filled orbitals have a lower energy. Makes them more stable. Changes the filling order
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Write these electron configurations
Titanium - 22 electrons 1s22s22p63s23p64s23d2 Vanadium - 23 electrons 1s22s22p63s23p64s23d3 Chromium - 24 electrons 1s22s22p63s23p64s23d4 is expected But this is wrong!!
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Chromium is actually 1s22s22p63s23p64s13d5 Why?
This gives us two half filled orbitals. Slightly lower in energy. The same principal applies to copper.
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Copper’s electron configuration
Copper has 29 electrons so we expect 1s22s22p63s23p64s23d9 But the actual configuration is 1s22s22p63s23p64s13d10 This gives one filled orbital and one half filled orbital. Remember these exceptions
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