1. The Atom

2. Atomic States An atom can be in one of two states: 1.Ground State: When an atom has the lowest possible amount of energy. 2.Excited State: When an atom has excess energy.

3. Excited vs. Ground State An atom without energy begins at ground state. When an atom absorbs energy from an outside source, it enters an excited state. When an atom emits a photon of light, it returns back to it’s ground state.

4. Energy Level Diagram Energy in the photon that is emitted corresponds to the energy used by the atom to get to the excited state.

5. The Hydrogen Atom Only certain types of photons are produced when Hydrogen atoms release energy. This is because only certain energy changes are occurring. Hydrogen has certain discrete energy levels.

6. The Hydrogen Atom If a hydrogen atom emits a red photon, it has released a small amount of energy. If a hydrogen atom emits a blue photon, it has released a larger amount of energy.

7. The Hydrogen Atom Each photon (or packet of light energy) corresponds to a particular energy change in the hydrogen atom. From this diagram, one can see the 4 discrete energy levels of Hydrogen that correspond to the 4 colors of visible light emitted.

8. The Wave Mechanical Model Scientists knew that the Bohr model was incorrect. They needed a better model. The Wave Mechanical Model described the atomic states by using ORBITALS. Orbitals are NOT like orbits.

9. The Wave Mechanical Model The Wave Mechanical Model, using the orbital, suggests there is the highest probability of finding the electron at any particular moment near the center of the atom. You can’t be sure the electron will be near the center of the atom, but it probably will. The electron’s path cannot be precisely described, only a prediction of it’s probability. The model gives NO information about when the electron occupies a certain point in space or how it moves.

10. The Hydrogen Orbitals We have already discussed that the Hydrogen atom has 4 discrete energy levels. These are called “Principal Energy Levels” These energy levels are labeled with whole numbers

11. The Hydrogen Energy Levels The energy levels are then further divided into sublevels. Principal Energy Level 1, consists of one sublevel: 1s. Principal Energy Level 2, consists of two sublevels: 2s and 2p.

12. The Hydrogen Energy Levels Principal Energy Level 3, consists of three sublevels: 3s, 3p, and 3d. Principal Energy Level 4, consists of four sublevels: 4s, 4p, 4d, and 4f.

13. Energy Levels & Orbitals These sublevels contain spaces for the electron that we call orbitals. Principal energy level 1 consists of just one sublevel or one type of orbital. This orbital is spherical in shape. We label this orbital 1s. The number 1 is for the principal energy level. The s labels the particular sublevel.

14. Energy Levels & Orbitals Principal Energy Level 2 has 2 sublevels: 2s & 2p. The 2s sublevel consists of one orbital: 2s. The 2p sublevel consists of three orbitals: 2p x, 2p y, 2p z.

15. Orbitals Different orbitals have different shapes. The s orbital is always a sphere. It can hold 2 electrons. The p orbital has 2 lobes. Each set of lobes: x, y, & z can hold 2 electrons, so the p orbital can hold a total of 6 electrons. The d and f orbitals have other shapes.