1: Looking Inside the Black Box

1. 1: Looking Inside the Black Box Video Review Made by J.LEFFEL Want more Chem? www.srhschem.wikispaces.com YouTube: LEFFELlabs

2. 1. For each of the following, explain what Rutherford determined about the atom. • A. Most of the alpha particles flew through the foil. Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected. Gold Foil Alpha Particle Emitter In order for the alpha particles to pass through the atoms, the atom must be empty space, with nothing to block the path of the alpha particles. EXTREME CLOSE UP! +

3. 1. For each of the following, explain what Rutherford determined about the atom. • B. Some of the alpha particles bounced back. About 1 in 8000 positive alpha particles were deflected. In order for them to bounce back, they would have to ricochet off of something very dense and heavy. Gold Foil Alpha Particle Emitter This object would also have to have a positive charge to deflect the positive alpha particles. Later, the dense positive object in the center of the atom become known as the nucleus – made of protons and neutrons. EXTREME CLOSE UP! +

4. 1. For each of the following, explain what Rutherford determined about the atom. • C. How are these results inconsistent with the plum pudding model of the atom? The plum pudding model is just a sphere of positive empty space with electrons embedded in. + + All of the alpha particles would have gone through if plum pudding was the correct model of the atom. + + + + But INSTEAD, Rutherford saw some bounce back, so he knew plum pudding could not be right. Thompson’s Plum Pudding Model

5. 1. For each of the following, explain what Rutherford determined about the atom. • D. How should the plum pudding model of the atom be changed to reflect this evidence? • Add a dense, positive nucleus: this is why some alpha particles bounced back. • The rest is empty space: this is why most alpha particles flew straight through.

6. 2. Complete the table below about subatomic particles. Nucleus Positive Nucleus Neutral Orbiting Nucleus Negative + + + +

7. 3. Complete the table below about isotopes. 1 Hydrogen-3 1 1 2 3 27 27 28 32 59 0 +1 Hydrogen-1 1 26 93 27 Cobalt-93 Nickel-62 28 34 -2 Mass # = p+ + N0 Charge = p+- e- Atomic # = #p+ AP! Mass # Cobalt-59 Atomic # Element Mass #

8. 4. In the table above… • A. Which letters represent isotopes? • Isotopes: same # of protons (atomic #), but different # neutrons (mass #). • A & C, B & D

9. 4. In the table above… • B. Which represent cations? • Cation: positively charged particle; C & D • C. Which represent anions? • Anion: negatively charged particle; B & E

10. 5. In an isotope, the ____ is always the same, but the ____ varies. # of protons/ atomic # • In an isotope, the __________ is always the same, but the ____________ varies. Both are correct because the # protons = the atomic # # of neutrons/ mass # Both are correct because mass # = protons + neutrons

11. 6. Why are different colors of light given off during a flame test? • Electrons absorb energy (during the flame test lab this energy is supplied by the heat of the flame) • Jump up in energy level – but this is unstable (excited state) • Fall back down by releasing energy – returns to the stable ground state • While falling down, the energy is released as light; the amount of energy released determines the color Energy Energy

12. 7. What elements are found in the mixture below? Because the bright spectra lines for lithium and strontium match the mixture, these two elements must be the mixture. LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com LEFFELlabs www.srhschem.wikispaces.com

13. 8. Explain how to use the number of protons to identify an element. • The number of protons is the atomic number • Find the atomic number on the table of elements

14. 9. Ms. L needs to measure out 10mL of a liquid. Which should she use? Graduated cylinders are more accurate than a beaker!

15. 10. Convert each of the following: 1000 mL = 1 L • 56.36 liters to milliliters • 15689 grams to kilograms • 200 centimeters to meters 1000 g = 1 Kg 100 cm = 1 m

16. 11. Calculate the average atomic mass of bromine. • One isotope of bromine has an atomic mass of 78.92 amu and a relative abundance of 50.69%. The other major isotope of bromine has an atomic mass of 80.92 amu and a relative abundance of 49.31%. 50.69 0.5069 78.92 40.004548 100 100 49.31 0.4931 80.92 39.901652 Multiply decimal by atomic mass Add up 79.9062 amu Divide by 100

17. 12. What are the signs of a chemical reaction? • Color change • Formation of a solid • Change in temperature • Formation of a gas • Decomposition • Light, energy, or heat given off

18. 13. Provide an example of the Law of Conservation of Mass. • During any chemical or physical change, mass before = mass after • Closed system CO2 CO2 10 grams of wood and O2 10 grams of ash, H2O, and CO2 H2O

19. Tips for Test Taking • Complete your review • Circle questions that you do not understand • Ask questions • Make flash cards for tricky topics only • Making them for all topics is a waste of time • Look over previous quizzes • Check which questions you got correct, find the answers to the ones you got wrong • The night before… • Take about 30 minutes to go over review • Sleep! • Eat breakfast! Made by J.LEFFEL Want more Chem? www.srhschem.wikispaces.com YouTube Channel: LEFFELlabs