Atomic Theory and Structure

1. Atomic Theory and Structure

2. The Theory of the Atom • ___________, a Greek teacher in the 4th Century B.C., first suggested the idea of the atom. • All matter is composed of tiny, _________ particles called _______ • http://images.google.com/imgres?imgurl=http://www.furryelephant.com/lib/swf/radioactivity/preview/re7Ms66.jpg&imgrefurl=http://www.furryelephant.com/content/radioactivity/democritus-lavoisier-dalton/&usg=__l-hTL60sR3IuOH7Z68HEc4nEp40=&h=126&w=195&sz=11&hl=en&start=3&um=1&tbnid=qyhFfwms7UcLvM:&tbnh=67&tbnw=104&prev=/images%3Fq%3DDalton%2527s%2BAtom%26hl%3Den%26sa%3DN%26um%3D1 Democritus indivisible atoms

3. John Dalton • In 1803, ____________ studied experiments and concluded that the properties of matter could be explained in terms of _____. atoms

4. Atomic Theory • Dalton’s _____________ had 4 points • Each ________ is composed of extremely small particles called atoms (which are indivisible). • All atoms of a given element are _______, but they differ from those of any other element. element identical

5. Atomic Theory Continued… created 3. Atoms are neither ________ nor ________ in any chemical reaction. 4. A given _________ always has the same relative numbers and kinds of atoms. destroyed compound

6. Dalton’s Model of the Atom He believed the atom was a solid sphere http://images.google.com/imgres?imgurl=http://www.furryelephant.com/lib/swf/radioactivity/preview/re7Ms66.jpg&imgrefurl=http://www.furryelephant.com/content/radioactivity/democritus-lavoisier-dalton/&usg=__l-hTL60sR3IuOH7Z68HEc4nEp40=&h=126&w=195&sz=11&hl=en&start=3&um=1&tbnid=qyhFfwms7UcLvM:&tbnh=67&tbnw=104&prev=/images%3Fq%3DDalton%2527s%2BAtom%26hl%3Den%26sa%3DN%26um%3D1

7. The Atom • Is composed of an __________ is an atom. • The atom is made up of three ___________ particles: ________, ___________ and __________ ELEMENT SUBATOMIC PROTONS NUETRONS ELECTRONS

8. electrical • Michael Faraday • 1893 • Atoms contain particles that have an __________ charge

9. Electron • Discovered in 1897 by __________ • Has a _________ charge JJ Thomson negative

11. Thomson also thought in addition to the negatively charged electrons, there must be something with a __________ charge because the overall charge of the atom is ___________ positive neutral

12. Plum Pudding Model

13. Ernest Rutherford 1909 • Performed Gold Foil Experiment in ______. • He shot _______ particles (very small, dense, fast and positively charged particles) at a thin layer of gold foil. alpha

14. Gold foil Alpha particles source Detector screen Alpha particles Because of Thomson’s Atom

15. But, what he found was this…

16. Most of the alpha particles went straight through but a tiny amount were deflected In the atom there was something dense enough to deflect the alpha particles = ________ Like this… nucleus

17. Importance of Rutherford’s Experiment space nucleus positive protons 1. Showed most of the atom is made up of empty __________ 2. Proved the atom had a small, dense area in its center known now as the _____________ 3. The nucleus has a _________ charge (must have __________ in it)

18. Rutherford’s Atom

19. Other important discoveries……

20. Neutron James Chadwick • Discovered in 1932 by ____________ • Has no charge (i.e. It is ______) neutral

21. Proton 1886 • Discovered in ______ by E. Goldstein • Has a ________ charge positive

22. Bohr Model

23. nucleus Modern Atomic Structure • The atom is made up of 2 parts/sections (1) The _________ --- (in the center of the atom; contains protons and neutrons) (2) The _____________ --- (surrounds the nucleus) electron cloud Nucleus (protons and neutrons) Electrons cloud (electrons)

25. http://images.google.com/imgres?imgurl=http://www.furryelephant.com/lib/swf/radioactivity/preview/re7Ms66.jpg&imgrefurl=http://www.furryelephant.com/content/radioactivity/democritus-lavoisier-dalton/&usg=__l-hTL60sR3IuOH7Z68HEc4nEp40=&h=126&w=195&sz=11&hl=en&start=3&um=1&tbnid=qyhFfwms7UcLvM:&tbnh=67&tbnw=104&prev=/images%3Fq%3DDalton%2527s%2BAtom%26hl%3Den%26sa%3DN%26um%3D1http://images.google.com/imgres?imgurl=http://www.furryelephant.com/lib/swf/radioactivity/preview/re7Ms66.jpg&imgrefurl=http://www.furryelephant.com/content/radioactivity/democritus-lavoisier-dalton/&usg=__l-hTL60sR3IuOH7Z68HEc4nEp40=&h=126&w=195&sz=11&hl=en&start=3&um=1&tbnid=qyhFfwms7UcLvM:&tbnh=67&tbnw=104&prev=/images%3Fq%3DDalton%2527s%2BAtom%26hl%3Den%26sa%3DN%26um%3D1

26. The Atom • The smallest particle of an ________ is an atom. • The atom is made up of three _________ particles: _______, _________, and _______ element subatomic protons neutrons electrons

27. -24 + -24 -28 -

29. Protons

31. Overall Charge 0 equal electrons The overall charge of an atom is ____(neutral) So, the number of protons must _______ the number of electrons So, the atomic number also tells us the number of _______________in an atom

32. Mass Number AMU’s protons neutrons The mass of an atom Measured in ________ Equal to the total number of __________ and __________

35. How to determine…….. atomic number atomic number Mass number 1) The number of protons = Look at ______________ 2) The number of electrons = Look at ______________(number of protons = number of electrons) 3) The number of neutrons = ___________ – atomic number

36. Practice Problems 1) Find the # of e-, p+ and n0 for sodium. (mass # = 23) 2) Find the # of e-, p+ and n0 for uranium. (mass # = 238) 3) What is the atomic # and mass # for the following atom? # e- = 15; # n0 = 16

37. Ions electrons ion • When an atom loses or gains one or more ________, it acquires a net electrical charge and is called an ____. • 2 types of ions: • 1) Anion • 2) Cation

38. Anions and Cations Anion negative Cation positive ____________: An ion that has more electrons than protons has a ___________ charge. **(Gained Electrons)** ____________:An ion that has fewer electrons that protons has a _____________ charge. **(Lost Electrons)**

40. Determining the Charge of an Ion # of protons - # of electrons

41. Ion Notation

42. Practice Problems 1) A neutral magnesium atom (atomic number 12) has 12 protons and 12 electrons. If the atom loses 2 electrons, what is the charge of the resulting ion? 2) How many electrons would be found in the ion O2-? 3) If an ion has 28 protons and 26 electrons, what is its charge? What is its symbol (including charge)?

43. Isotopes • An isotope refers to atoms that have the same # of ______, but they have a different # of _______. • Because of this, they have different ____ #’s (or simply, different ______.) protons neutrons mass masses

44. atomic mass Exm: (1) Carbon-12 & Carbon-13 (2) Chlorine-35 & Chlorine-37 (The # shown after the name is the mass #.) For each example, the elements have identical ______ #’s, but different _____ #’s

45. Isotopes cont… mixture percentage In nature, elements are found as a _______________ of all their isotopes The isotopes are found in the same __________________

48. More Practice Problems 1) Find the # e-, p+ and n0 for Xe-131. 2) Find the # e-, p+ and n0 for Cu 3) Write a shorthand way to represent the following isotope: # e- = 1 # n0 = 0 # p+ = 1 63 29

49. Atomic Mass • The atomic masses listed in the Periodic Table are a “_____________” of all the isotopes of the element. weighted average

50. Practice Problems (1) Mrs. Smith’s geometry semester grades are calculated using a weighted average of three category scores: Tests/Quizzes= 30% of your grade Homework/Participation=60% of your grade Semester Exam= 10% of your grade If a student had the following scores, what would they receive for the semester? Tests/Quizzes= 80 (B-) Homework/Participation= 60 (D-) Semester Exam=65 (D)