Democritus Model Main idea: atoms are uniform, solid, indestructible

1. Democritus Model Experiments: keep breaking a seashell until you can’t anymore to reach the atom

   Democritus Model Shortcomings: no experimental evidence; He believed that atoms are fully solid with no internal structure; illogical for a void of nothingness to exist; Believed that different atom shapes relate to different properties

   Democritus Model Other key info: based on reasoning, not science
   Empedocles Model Main idea: all matter is made up of different ratios of earth, fire, water, and air

2. Empedocles Model Scientist: Aristotle

3. other key info: chemical reactions happen when they are converted from one form to another

4. Solid Sphere Model Main idea: atoms are spheres that cannot be broken down

   Solid Sphere Model Scientist: John Dalton

   Solid Sphere Model Shortcomings: does not mention isotopes, ions, nucleus, or subatomic particles

   Solid Sphere Model Other key info: Based on the law of conservation of mass and the law of constant composition

5. Plum Pudding Main idea: negative force exists in the atom floating around; something positive exists as well (probably floating around)

   Plum Pudding Scientist: JJ Thomson

   Plum Pudding Experiments: Experiments with Cathode Rays: A glass tube with some air inside and high voltage is applied. Causes a  beam of negatively charged particles to flow

   Plum Pudding Shortcomings: protons are centered in the nucleus

   Plum Pudding Other key info: used cathode rays

   Nuclear Model Main idea: Nuclear model consists of a small positively charged nucleus surrounded by orbiting negatively charged electrons

   Nuclear Model Scientist: Ernest Rutherford

   Nuclear Model Experiments: Gold Foil experiment - Positively charged alpha particles were fired at a very thin sheet of pure gold; Predicted: Alpha particles would pass straight through the gold foil, as there was no strong positive aspect of the atom to interfere

   Nuclear Model Shortcomings: failed to explain the stability of electrons

6. Planetary Model Main idea: electron orbitals

   Planetary Model Scientist: Niels Bohr

   Planetary Model Shortcomings - explains the stability of an atom but only worked for the hydrogen atom

   Planetary Model Other key info - in model, all electrons are quantized

   1. Quantum Model Main idea: the law of uncertainty (the more you know about location, the less you know about energy and vice versa)

   2. Quantum Model Scientist: Erwin Shrodinger

   3. Quantum Model Other key info: based on probability, not certainty

      What are the three subatomic particles? Protons, neutrons, and electrons

7. What is a nucleus? Most of the mass of the atom; contains protons and neutrons

8. Which subatomic particle distinguishes one atom from another? protons

9. How do you write a nuclear symbol? You write the atomic symbol in the middle; atomic mass on the top left; atomic number on the bottom left; the charge (if any) on the top right

10. What is an ion? An atom with a charge

11. What is a positively charged ion? cation

12. What is a negatively charged ion? anion

13. Are all atoms ions? No, but most are because they want to have a full valence shell

14. Are all atoms isotopes? yes.

15. What are isotopes? Atoms with different masses (neutrons)

16. What are the uses of a radioactive isotope? Can be used in geological dating, treating cancer, killing bacteria, and tracers in medical diagnosis

1. What is average atomic mass? The average mass of all of the atoms of that element

2. How do you calculate the average atomic mass? Multiply the mass by the fraction it appears in the world; add all of them up together

3. What is mass spectroscopy? an analytical tool that measures the atomic mass of an element

4. What are some real-world uses of mass spectroscopy? Forensics, soil contamination, medicine

1. What is an element? a pure substance that consists entirely of one type of atom

2. What is a compound? a pure substance formed by two or more different elements

3. How do you read a chemical formula? from left to right; coefficient x subscript

4. What are molecules? the simplest part of a covalent substance that retains all of the properties of a substance and exists in a free state

5. What does the subscript of a chemical formula mean? The number of atoms in one mole

6. What does the coefficient of a chemical formula mean? The number of moles

7. What is a pure substance? made up of only one kind of element or compound

8. What is a mixture? combination of two or more pure substances in which each pure substance retains its individual chemical properties

9. What is a homogeneous mixture? Particles are equally mixed throughout the mixture

10. What is an example of a homogenous mixture? a mixture that has constant composition throughout

11. What are the examples of homogeneous mixtures? mercury/silver fillings

12. What is the difference between a solvent and a solute? The solvent dissolves the solute

13. What is the universal solvent? water

14. What is a heterogeneous mixture? a mixture that does not blend smoothly through and in which the individual substances remain distinct

15. What is an example of a heterogeneous mixture? salad dressing

16. What are the types of heterogeneous mixtures? colloid and suspension

17. What is a colloid? Looks like a solution

18. How do you determine the difference between a colloid and a solution? Tyndall’s Law - shine a flashlight; colloids scatter the light

19. What is a suspension? a mixture of two visibly unmixable things

20. What are the separation techniques? Describe each one.

    1. hand separation: if the particles are large and distinct enough

    2. separation by magnetism: if one component is magnetic and the other is not

    3. filtration: a technique that uses a porous barrier to separate a solid from liquid

    4. Distillation: difference in boiling points

    5. Crystallization: supersaturated solution

21. What is dialysis? a process that removes waste and excess from the body

22. What is the relationship between distillation and healthcare? recovering reactants, purifying medicines, isolating compounds

23. What are the types of chromatography? Gas, column, thin layer chromatography

24. How does chromatography help law enforcement? Chemical analysis and gas chromatography

1. When do nuclear reactions happen? Nuclei split, combine, emit radiation

2. What subatomic particle changes? Protons because you are making a new element

3. What is nuclear fission? Breaking apart of the nucleus

4. What is nuclear fusion? Joining nuclei (happens at the sun)

5. What are radioisotopes? Radioactive isotopes

6. What is the “magic” stability number? 60 AMU

7. What element is considered the most stable? nickel

8. What is alpha decay? Most stable; higher mass atoms do it; lose a hydrogen atom

9. What is beta decay? Lose an electron

10. What is gamma decay? Lose photons

11. What is half-life? The amount of time it takes for radioactive material to become half of its original mass

12. What is a decay curve? Exponential graph representing radioactive decay

1. Explain Coulomb’s Law. binding energy = (charge of particle 1 x charge of particle 2)/ radius^2

2. What are the three types of bonds? Ionic (nonmetal/metal; GIVE), covalent (nonmetal/nonmetal; SHARE), and metallic (metal/metal)