1. Chapter 2 Atoms, Molecules, & Ions

2. Atomic Theory Elements composed of atoms Atoms can’t be changed Compounds of multiple atoms John Dalton

3. Conservation of Mass In ordinary chemical reactions, matter can be neither created nor destroyed

4. Constant Composition Compounds contain elements that are always in the same proportions

5. Multiple Proportions The elements making up a compound will form whole number ratios

6. Atom The smallest particle an element can be broken down into and still maintain the identity of the element

7. Nuclear Atom Proved by Rutherford & Bohr in the famous gold foil experimentsgold foil experiments

8. Atomic Composition Proton: in the nucleus Neutron: in the nucleus Electron: outside the nucleus

9. Proton In Nucleus +1 relative charge About 1 amu in mass

10. Neutron In nucleus Neutral, zero charge Mass is about 1 amu

11. Electron Outside the nucleus -1 in relative charge Negligible mass about 1/2000 amu

12. Electron Charge Determined by Robert Milliken in the famous oil droplet experimentoil droplet experiment

13. Atomic Number The number of protons in an element Z number

14. Mass Number The number of protons and neutrons in an atom A - number

15. Nuclear Symbol A 4 X He Z 2 GeneralSpecific FormulaExample

16. Isotopes Atoms that contain the same number of protons, but different number of neutrons Z constant, A variable

17. Isotopes are useful! C 14 - dating Isotopic-tracing

18. Shorthand for isotopes Instead of full notation: 14 CWrite: C-14 6 So, only the Z number (protons + neutrons)

19. Atomic Mass All elements have >1 isotope. The percentage of one isotope is its relative abundance. Atomic mass = (isotopic mass # 1 multiplied by % of isotope #1) + (isotopic mass # 2 multiplied by % of isotope # 2) + etc… Usually about 3 or 4 isotopes for a given element is maximum.

20. Periodic Table Graphic hierarchy of all the elements. The order is used to predict size, charge, electronic structure, & reactivity of elements

21. Periods Rows which indicate energy level or shell or size of the atoms

22. Groups or Families Columns which indicate the number of electrons in the outermost energy level determining charge & reactivity

23. Metals Left three quarters of the chart Lose electrons Become positive

24. Nonmetals Upper right portion Gain, lose, or share electrons when they react

25. Metalloids Along the stair-stepped line from B to At Share properties of metals & nonmetals

26. Radioactivity The spontaneous breakdown of an unstable nucleus

27. Radioactive Decay Alpha radiation Beta radiation Gamma radiation

28. Alpha Particle Helium nucleus 2 protons & two neutrons mass = 4 & charge = +2 Low penetrating power

29. Beta Particle High speed electron Mass = 0 & charge = -1 Medium penetrating power

30. Gamma Rays High energy electromagnetic wave No mass or charge Very high penetrating power

31. Compound A group of atoms that are chemically combined

32. Molecule A compound that can exist by itself

33. Diatomic Molecule Two atoms of the same element that are chemically combined Cl 2, F 2, O 2

34. Ion Charged Particle Cl -1

35. Polyatomic Ion A group of atoms chemically combined that together has a charge SO 4 -2

36. Binary Compound A compound made up of two elements in any ratio NaCl Mg 3 P 2

37. Chemical Formula A formula that shows the number and kinds of atoms in a compound CaCO 3

38. Molecular Formula A formula that shows the number and kinds of atoms in a molecule C 6 H 12 O 6

39. Atomic Structure List & describe the three subatomic particles

40. Atomic Structure Fill in the Chart: Isotope protons neutrons electrons U-235 - - - - 56 80 - - - 14 13

41. Calculate the atomic mass of the element made up of the following isotopes: 99.50 % H-1 0.30 % H-2 0.20 % H-3

42. Calculate Pt’s atomic mass : 5.0 % Pu-242 5.0 % Pu-243 80.0 % Pu-244 10.0 % Pu-245

43. Determine the number of atoms in each compound C 6 H 12 O 6 NaNO 3 H 3 PO 4 Al 2 (SO 4 ) 3

44. List & describe each of the three types of radiation