Atomic Structure: Photoelectron Spectroscopy and Atomic Structure, Exercises of Chemistry

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AP Chemistry

Day 5 Unit 1 Atomic Structure 1.5 Atomic Structure 1.6 Photoelectron Spectroscopy

18. Balance this using variables x and y:

C (^) xH (^) y + (¼ y +x) O 2 → x CO 2 + ½ y H 2 O

Try a couple of examples -

Photoelectric effect (Einstein’s Nobel Prize Winning paper)

Light consists of photons (little “packets” of energy defined by E = h𝝂, where h is Planck’s constant and is the 𝝂 frequency of the light.) Einstein was the first to explain the Photoelectric effect - when certain photons of light are directed on a substance, the electrons form the atoms in the material could be ejected.

Photoelectric effect

Removal of electron depends on energy of photons not their intensity - photons have to overcome the electron’s attraction to the nucleus (i.e. its electrostatic potential energy). E = h𝝂 𝝂 is frequency of the photon Since c = ƛ𝝂 E = hc / ƛ c= speed of light, 3.0 x 10 8 m/s

Coulomb’s law F (^) coulombic 𝝰 q 1 q (^2) r 2 Thus the more negative the F (^) coulombic , the stronger the attraction between the electron and the nucleus.

Electrostatic forces now Coulombic forces?

Photoelectron Spectroscopy What does a photoelectron spectrum tell us about the structure of an atom? Why?

When scientists first discovered X-rays, they realized they could do more than just make images of people’s bones. X-rays could also allow them to “see” inside the atom. They could not do this directly, but in looking for patterns in ionization energy data they were able to determine the energy levels and sublevels of electrons and how many electrons were in each level.

Model 1 - A Soccer Player in a Ditch (football player)

1. Consider Model 1. Imagine that a football player is trying to kick a ball out of a ditch. a) What force of attraction is keeping the soccer ball at the bottom of the ditch?

Model 1 - A Soccer Player in a Ditch (football player)

1. Consider Model 1. Imagine that a football player is trying to kick a ball out of a ditch. a) What force of attraction is keeping the football at the bottom of the ditch? The force of gravity is keeping the football in the ditch.

Model 1 - A Soccer Player in a Ditch (football player)

1. Consider Model 1. Imagine that a football player is trying to kick a ball out of a ditch. b) Which type of energy must be overcome to get the ball out of the ditch - potential or kinetic? Potential energy has to be overcome to get the ball out of the ditch.

Model 1 - A Soccer Player in a Ditch (football player)

1. Consider Model 1. Imagine that a football player is trying to kick a ball out of a ditch. c) Which type of energy must the ball have to get out of the ditch - potential or kinetic. The ball must have kinetic energy if it is to get out of the ditch.

Model 1 - A Soccer Player in a Ditch (football player)

3. Describe what happens to the ball if the football player’s kick provides:

a) 30 J of energy to the ball in the ditch.

The ball must would not reach the top of the ditch and would roll back down to the player’s feet.

Model 1 - A Soccer Player in a Ditch (football player)

3. Describe what happens to the ball if the football player’s kick provides: b) 45 J of energy to the ball in the ditch. The ball must would just reach the top of the ditch and stop.

Model 1 - A Soccer Player in a Ditch (football player)

4. For each of the scenarios in Q.3 where the ball successfully leaves the ditch determine the KE the ball will have when it reaches the top of the ditch.

b)The ball leaves the ditch and has 0J KE at the top.

c) 15J of KE at the top.

Model 1 - A Soccer Player in a Ditch (football player)

5. Construct the algebraic equation that shows the relationship among the energy of the player’s kick (KE (^) kick), the potential energy of gravity on the ball (PE) and the kinetic energy the ball will have as it leaves the ditch (KE (^) roll)

KE kick = PE + KE roll