1. Chapter 5 Electrons In Atoms 5.1 Revising the Atomic Model
5.2 Electron Arrangement in Atoms
5.3 Atomic Emission Spectra and
the Quantum Mechanical Model
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2. Limitations of Rutherford’s Atomic Model
Energy Levels in Atoms
Limitations of Rutherford’s Atomic Model
It explained only a few simple properties of atoms.
It could not explain the chemical properties of elements.
For example, Rutherford’s model could not explain why an object such as the iron scroll shown here first glows dull red, then yellow, and then white when heated to higher and higher temperatures.
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3. Energy Levels in Atoms
The Bohr Model
In 1913, Niels Bohr (1885–1962), a young Danish physicist and a student of Rutherford, developed a new atomic model.
He changed Rutherford’s model to incorporate newer discoveries about how the energy of an atom changes when the atom absorbs or emits light.
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4. Energy Levels in Atoms
The Bohr Model
Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus.
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5. Each possible electron orbit in Bohr’s model has a fixed energy.
Energy Levels in Atoms
The Bohr Model
Each possible electron orbit in Bohr’s model has a fixed energy.
The fixed energies an electron can have are called energy levels.
A quantum of energy is the amount of energy required to move an electron from one energy level to another energy level.
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6. Energy Levels in Atoms
The Bohr Model
The rungs on this ladder are somewhat like the energy levels in Bohr’s model of the atom.
A person on a ladder cannot stand between the rungs. Similarly, the electrons in an atom cannot exist between energy levels.
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7. Energy Levels in Atoms
The Bohr Model
The rungs on this ladder are somewhat like the energy levels in Bohr’s model of the atom.
The energy levels in atoms are unequally spaced, like the rungs in this unusual ladder. The higher energy levels are closer together.
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8. Bohr’s model is only valid for the first 20 elements
Bohr’s model is only valid for the first 20 elements. look at a periodic table
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9. Let’s build the first 20 elements using our models
You need to know some rules
Level n = 1 can hold a total of 2 electrons
All other levels can hold 8 electrons
Take a picture of each completed and labeled atom.
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10. The Quantum Mechanical Model
What does the quantum mechanical model determine about the electrons in an atom?
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11. The Quantum Mechanical Model
The quantum mechanical model determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus of an atom.
Areas of probability
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12. How are the quantum mechanical model and the Bohr model alike
How are the quantum mechanical model and the Bohr model alike? How are they different?
Like the Bohr model, the quantum mechanical model restricts the energy of electrons to certain values. Unlike the Bohr model, the quantum mechanical model does not specify an exact path the electron takes around the nucleus.
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13. How do sublevels of principal energy levels differ?
Atomic Orbitals
Atomic Orbitals
How do sublevels of principal energy levels differ?
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14. Different atomic orbitals are denoted by letters.
The s orbitals are spherical.
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15. Different atomic orbitals are denoted by letters.
The s orbitals are spherical.
The p orbitals are dumbbell-shaped.
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16. Atomic Orbitals
For a given principal energy level greater than 1, there is one s orbital, 3 p orbitals...
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17. Atomic Orbitals
For a given principal energy level greater than 1, there is one s orbital, 3 p orbitals, and 5 d orbitals.
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18. Atomic Orbitals
Four of the five d orbitals have the same shape but different orientations in space.
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19. Atomic Orbitals
The numbers and types of atomic orbitals depend on the principal energy level.
Summary of Principal Energy Levels and Sublevels
Principal energy level
Number of sublevels
Type of sublevel
Maximum number of electrons
n = 1 1
1s (1 orbital) 2
n = 2
2s (1 orbital), 2p (3 orbitals) 8
n = 3 3
3s (1 orbital), 3p (3 orbitals),
3d (5 orbitals) 18
n = 4 4
4s (1 orbital), 4p (3 orbitals),
4d (5 orbitals), 4f (7 orbitals) 32
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20. END OF 5.1
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