1. 5.1
Light and Atoms .

2. The Development of Atomic Models
5.1
The Development of Atomic Models
The Development of Atomic Models
What was inadequate about Rutherford’s atomic model?

3. The Development of Atomic Models
5.1
The Development of Atomic Models
Rutherford’s atomic model could not explain the chemical properties of elements.
Rutherford’s atomic model could not explain why objects change color when heated.
Rutherford’s model fails to explain why objects change color when heated. As the temperature of this horseshoe is increased, it first appears black, then red, then yellow, and then white. The observed behavior could be explained only if the atoms in the iron gave off light in specific amounts of energy. A better atomic model was needed to explain this observation.

4. The Development of Atomic Models
5.1
The Development of Atomic Models
The timeline shows the development of atomic models from 1913 to 1932.
These illustrations show how the atomic model has changed as scientists learned more about the atom’s structure.

5. Electrons orbit the nucleus in “shells”
Bohr’s model
Bohr Model
Electrons orbit the nucleus in “shells”
Electrons can be bumped up to a higher shell if hit by an electron or a photon of light.

6. According to the wave model, light consists of electromagnetic waves.
5.3
Light
According to the wave model, light consists of electromagnetic waves.
Electromagnetic radiation includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays.
All electromagnetic waves travel in a vacuum at a speed of  108 m/s.

7. According to the wave model, light consists of electromagnetic waves.
5.3
Light
According to the wave model, light consists of electromagnetic waves.
Electromagnetic radiation includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays.
All electromagnetic waves travel in a vacuum at a speed of  108 m/s.

8. 5.3
Light
The electromagnetic spectrum consists of radiation over a broad band of wavelengths.
The electromagnetic spectrum consists of radiation over a broad band of wavelengths. The visible light portion is very small. It is in the 10-7m wavelength range and 1015 Hz (s-1) frequency range. Interpreting Diagrams What types of nonvisible radiation have wavelengths close to those of red light? To those of blue light?

9. 5.3
Atomic Spectra
Atomic Spectra
What causes atomic emission spectra?

10. 5.3
Atomic Spectra
When atoms absorb energy, electrons move into higher energy levels. These electrons then lose energy by emitting light when they return to lower energy levels.

11. 5.3
Atomic Spectra
A prism separates light into the colors it contains. When white light passes through a prism, it produces a rainbow of colors.
A prism separates light into the colors it contains. For white light this produces a rainbow of colors.

12. 5.3
Atomic Spectra
When light from a helium lamp passes through a prism, discrete lines are produced.
A prism separates light into the colors it contains. Light from a helium lamp produces discrete lines. Identifying Which color has the highest frequency?

13. 5.1
The Bohr Model
The Bohr Model
What was the new proposal in the Bohr model of the atom?

14. 5.1
The Bohr Model
Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus.

15. Each possible electron orbit in Bohr’s model has a fixed energy.
5.1
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.

16. 5.1
The Bohr Model
Like the rungs of the strange ladder, the energy levels in an atom are not equally spaced.
The higher the energy level occupied by an electron, the less energy it takes to move from that energy level to the next higher energy level.
These ladder steps are somewhat like energy levels. In an ordinary ladder, the rungs are equally spaced. The energy levels in atoms are unequally spaced, like the rungs in this ladder. The higher energy levels are closer together.

17. The Quantum Mechanical Model
5.1
The Quantum Mechanical Model
Austrian physicist Erwin Schrödinger (1887– 1961) used new theoretical calculations and results to devise and solve a mathematical equation describing the behavior of the electron in a hydrogen atom.
The modern description of the electrons in atoms, the quantum mechanical model, comes from the mathematical solutions to the Schrödinger equation.

18. The Quantum Mechanical Model
5.1
The Quantum Mechanical Model
The propeller blade has the same probability of being anywhere in the blurry region, but you cannot tell its location at any instant. The electron cloud of an atom can be compared to a spinning airplane propeller.
The electron cloud of an atom is compared here to photographs of a spinning airplane propeller. a) The airplane propeller is somewhere in the blurry region it produces in this picture, but the picture does not tell you its exact position at any instant. b) Similarly, the electron cloud of an atom represents the locations where an electron is likely to be found.

19. The Quantum Mechanical Model
5.1
The Quantum Mechanical Model
In the quantum mechanical model, the probability of finding an electron within a certain volume of space surrounding the nucleus can be represented as a fuzzy cloud. The cloud is more dense where the probability of finding the electron is high.
The electron cloud of an atom is compared here to photographs of a spinning airplane propeller. a) The airplane propeller is somewhere in the blurry region it produces in this picture, but the picture does not tell you its exact position at any instant. b) Similarly, the electron cloud of an atom represents the locations where an electron is likely to be found.

20. Atomic Orbitals How do sublevels of principal energy levels differ?
5.1
Atomic Orbitals
Atomic Orbitals
How do sublevels of principal energy levels differ?

21. 5.1
Atomic Orbitals
An atomic orbital is often thought of as a region of space in which there is a high probability of finding an electron.
Each energy sublevel corresponds to an orbital of a different shape, which describes where the electron is likely to be found.

22. 5.1
Atomic Orbitals
Different atomic orbitals are denoted by letters. The s orbitals are spherical, and p orbitals are dumbbell-shaped.
The electron clouds for the s orbital and the p orbitals are shown here.

23. 5.1
Atomic Orbitals
Four of the five d orbitals have the same shape but different orientations in space.
The d orbitals are illustrated here. Four of the five d orbitals have the same shape but different orientations in space. Interpreting Diagrams How are the orientations of the dxy and dx2 – y2 orbitals similar? How are they different?

24. 5.1
Atomic Orbitals
The numbers and kinds of atomic orbitals depend on the energy sublevel.

25. 5.1
Atomic Orbitals
The number of electrons allowed in each of the first four energy levels are shown here.