1. Modern Atomic Theory Atomic Structure

2. I. Modern Atomic Theory A.An electron in an atom can move from one energy level to another when the atom gains or loses energy. 1)Where are electrons found in an atom? A.An electron in an atom can move from one energy level to another when the atom gains or loses energy. 1)Where are electrons found in an atom? 2)How do electrons in an atom differ in energy? 3) What happens when an electron emits energy and drops to a lower energy level? 4) What is the electron configuration? 5)Which electrons are most likely to jump to a higher energy level when they absorb energy? Why?

3. II. Bohr’s Atomic Model A.Niels Bohr 1)Developed an atomic model that included a)Protons b)Neutrons and c)Electrons 2)This model focused on the arrangement of a)Electrons - moving with constant speed in fixed orbits Like planets orbiting the sun A.Niels Bohr 1)Developed an atomic model that included a)Protons b)Neutrons and c)Electrons 2)This model focused on the arrangement of a)Electrons - moving with constant speed in fixed orbits Like planets orbiting the sun

4. III. Energy Levels A.Energy levels - the possible energies that electrons in an atom can have 1)Like steps in a staircase a)The bottom step has the lowest energy level 2)An electron in an atom can move from one energy level to another when the atom gains or loses energy. A.Energy levels - the possible energies that electrons in an atom can have 1)Like steps in a staircase a)The bottom step has the lowest energy level 2)An electron in an atom can move from one energy level to another when the atom gains or loses energy.

5. Practice  A boron atom has two electrons in the first energy level and three in the second energy level.  Sketch a diagram that shows this electron configuration.  Compare the relative energies of the electrons in these two energy levels. Which electrons have higher energy?  A boron atom has two electrons in the first energy level and three in the second energy level.  Sketch a diagram that shows this electron configuration.  Compare the relative energies of the electrons in these two energy levels. Which electrons have higher energy?

6. Probability Scientists use probability to describe how electrons behave in atoms. Try the following activity to learn more about probability. Repeat this process five times. 1.Describe the pattern of the stickers. 2.Was the probability of placing a sticker in the center of the circle high or low? 3.What could increase the probability of placing a sticker inside the circle? Probability Scientists use probability to describe how electrons behave in atoms. Try the following activity to learn more about probability. Repeat this process five times. 1.Describe the pattern of the stickers. 2.Was the probability of placing a sticker in the center of the circle high or low? 3.What could increase the probability of placing a sticker inside the circle?

7. Complete the Description of How a Gain or Loss of Energy Affects Atoms

8. IV. Atomic Orbitals A.The electron cloud represents all the orbitals in an atom. 1.An orbital is a region of space around the nucleus where an electron is likely to be found. a)The level in which an electron has the least energy -- the lowest energy level -- has only one orbital. A.The electron cloud represents all the orbitals in an atom. 1.An orbital is a region of space around the nucleus where an electron is likely to be found. a)The level in which an electron has the least energy -- the lowest energy level -- has only one orbital.

9. Number of Orbitals and Electrons in Energy Levels