THINK FIRST

DO NOT LET THIS BE YOU ON THE TEST DAY.ASK QUESTIONS SO WE CAN FIGURE IT OUT.

In your composition book, write down 2 or more questions that are not clear.If you understand everything, help your neighbor answer their questions.

Finish by: _______________

Chapter 4

What did we learn?• The atomic number (# of protons) determines an

element• An isotope has extra neutrons, and therefore extra

weight. How do you calculate # of neutrons?• If an element has many isotopes, we need to use an

average mass! Why??? How do we calculate this?• Who contributed to our understanding of an atom?

Dalton, Thomson’s Cathode Ray, Rutherford’s Gold Foil, Bohr, Millikan…

Practice Problems

How many electrons, neutrons, and protons are in Nitrogen-15? How do we write this? How about Nitrogen-17?

How do we calculate average atomic mass?

mass1 x percentage1 =mass2 x percentage2 = mass…n x percentage…n =

Σ__________

Calculate the average atomic mass of these three isotopes.

40 K at 89%19

41 K at 7%19

44 K at 4%19

Chapter 5

What did we learn?• # electrons in atom = # protons• Electrons are arranged in energy levels and can

move around (quantums!)• How do we arrange these electrons and write

this configuration out?• Light behaves as both a wave and particle. How

do we calculate energy of a photon and the frequency or wavelength of a wave?

Practice Problems

• What is the electron configuration of these elements?

40 K19

73 Ge32

9 B4

Which rules do these violate?

1s12s22p23s2 1s22s22p63s23p7

What is the electron configuration for these elements?

Mg Ar Sr

Photons and Quantums

Electrons can absorb and emit energy. What are some examples of this in our daily life?

c = λν E=hν

If a wave has a wavelength of 7.80 x 10-7 (IR light), what is the frequency? What is the energy of the photon?

Chapter 25.1

What did we learn?• There are 3 basic types of nuclear radiation

(alpha, beta, gamma) with special properties each.

• We can write out these equations using a simple set-up and balancing the number of protons and atomic mass on each side.

Alpha radiation is not that harmful unless ingested into the body. Why is this? Would you

be more worried about alpha or gamma radiation? Why?

Reactants → ProductsIf something is produced, it’s a product!

If it reacts, undergoes, or we start with it, it’s a reactant!

Cerium-142 undergoes beta-decay. Write this equation.Uranium-240 is produced from beta-decay. Write this equation.