0:56 0:55 0:54 0:53 0:57 0:58 1:02 1:01 1:00 0:59 0:52 0:51 0:44 0:43 0:42 0:41 0:45 0:46 0:50 0:49 0:48 0:47 1:03 1:04 1:19 1:18 1:17 1:16 1:20 1:21 1:25 1:24 1:23 1:22 1:15 1:14 1:08 1:07 1:06 1:05 1:09 1:10 1:13 1:12 1:11 0:40 0:39 0:09 0:08 0:07 0:06 0:10 0:11 0:15 0:14 0:13 0:12 0:05 0:04 0:00 0:00 0:00 0:00 0:00 0:00 0:03 0:02 0:01 0:00 0:16 0:17 0:32 0:31 0:30 0:29 0:33 0:34 0:38 0:37 0:36 0:35 0:28 0:27 0:21 0:20 0:19 0:18 0:22 0:23 0:26 0:25 0:24 3:00 1:26 2:30 2:29 2:28 2:27 2:31 2:32 2:36 2:35 2:34 2:33 2:26 2:25 2:18 2:17 2:16 2:15 2:19 2:20 2:24 2:23 2:22 2:21 2:37 2:38 2:53 2:52 2:51 2:50 2:54 2:55 2:59 2:58 2:57 2:56 2:49 2:48 2:42 2:41 2:40 2:39 2:43 2:44 2:47 2:46 2:45 1:27 2:14 1:43 1:42 1:41 1:40 1:44 1:45 1:49 1:48 1:47 1:46 1:39 1:38 1:31 1:30 1:29 1:28 1:32 1:33 1:37 1:36 1:35 1:34 2:13 1:50 2:06 2:05 2:04 2:03 2:07 2:08 2:12 2:11 2:10 2:09 1:51 2:02 1:55 1:54 1:53 1:52 2:01 1:56 2:00 1:57 1:59 1:58 Do Now Where are the electrons found in the Rutherford model of the atom? Revolving around the nucleus Why don’t they fall into the positively charged nucleus? Centripetal force Can the distance between the nucleus and an electron change?

Bohr Model of the Atom

Bohr Observations When solutions containing metal ions are heated, they give off characteristic colors. What does this mean? Bohr related the color of light to the electrons in an atom. Sodium Potassium Calcium Barium

Bohr’s Model of the Atom Electrons move around the nucleus like planets around the sun. In specific circular paths, or energy levels, different distances from the nucleus. An amount of fixed energy separates one level from another. When electrons fall to lower energy levels they release a certain color of light

The Bohr Model of the Atom I pictured the electrons orbiting the nucleus much like planets orbiting the sun. However, electrons are found in specific circular paths around the nucleus, and can jump from one level to another. Neils Bohr

Bohr’s model Energy levels of an atom like the rungs of a ladder The electron cannot exist between energy levels, just like you can’t stand between rungs on a ladder Electrons can absorb energy and move to a higher energy level The higher the energy level, the more unstable the electron Unstable electrons fall to lower energy levels and release light

} Bohr’s Model Further away from the nucleus means more energy. There is no “in between” energy High energy electrons are unstable and eventually fall to a lower energy level releasing light along the way Fifth Fourth Increasing energy Third Second First Nucleus

Principal Quantum Number Principal quantum number (n) denotes the shell (energy level) in which the electron is located. Maximum number of electrons that can fit in an energy level: 2n2

Principal Quantum Number Determining the maximum # of electrons in an energy level. # of electrons = 2n2 Eg. n=1 2(1)2=2 n=2 2(2)2=8 n=3 2(3)2=18

Changing Energy Levels Let’s look at a hydrogen atom

Changing Energy Levels Heat, electricity, or light can move the electron up energy levels

Changing Energy Levels As the electron falls back to ground state it gives the energy back as light

Changing Energy Levels May fall down in steps Each with a different energy

The Bohr Ring Atom n = 4 n = 3 n = 2 n = 1

Regents Practice