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Atomic Structure

3.1. Atomic Structure. October 1, 2015. Objective: Explain Dalton’s atomic theory and describe why it was more successful than Democritus’ atomic theory. Do Now: Name the 3 subatomic particles found in an atom (the 3 parts of an atom). Atomic History.

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Atomic Structure

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  1. 3.1 Atomic Structure

  2. October 1, 2015 • Objective: Explain Dalton’s atomic theory and describe why it was more successful than Democritus’ atomic theory. • Do Now: Name the 3 subatomic particles found in an atom (the 3 parts of an atom).

  3. Atomic History • In 400 BC a Greek Philosopher, Democritus suggested the universe was made of invisible units--atoms.

  4. 1800’s John Dalton’s Theory (Still Accepted) • Every element is made of tiny, unique particles called atoms • Atoms of different elements can join to form molecules.

  5. John Dalton’s Theory- Disproved • Atoms are the smallest particles and cannot be subdivided. • Atoms of the same element are exactly alike in mass

  6. JJ Thomson • Credited with discovering negative charged particles called electrons.

  7. https://www.youtube.com/watch?v=2xKZRpAsWL8 https://www.youtube.com/watch?v=O9Goyscbazk

  8. Rutherford • Credited with discovering nucleus. • and atoms are mostly empty space.

  9. https://www.youtube.com/watch?v=5pZj0u_XMbc

  10. http://micro.magnet.fsu.edu/electromag/java/rutherford/

  11. Further Research Finding • Later on, the discovery of protons and neutrons were discovered in the nucleus. • And it was later concluded that all atoms are neutral in charge. • The number of protons and electrons in any atom are always equal.

  12. Niels Bohr • Suggested that electrons move around atoms in set paths around the nucleus. • He said each path is an energy level

  13. See visual aid in Ch4 online txtbk

  14. Today’s Theory • It is impossible to pinpoint an electron’s exact position due to its tremendous speed. • Electrons do not move around in definite paths.

  15. Today’s Theory • Electrons are found in orbitals within energy levels. (s, p, d, and f ) • a region in an atom where there is a high probability of finding electrons.

  16. Today’s Theory • Electrons are now viewed as waves vibrating on a string rather than simple particles. • Wave-Particle Duality Theory

  17. What are atoms? • The smallest part of an element that still has the element’s properties.

  18. Parts of an atom • Nucleus • Proton • Neutron • Electron Subatomic particles

  19. Nucleus • center of an atom • positively charged • makes up 99.9% of the atom’s mass • contains protons and neutrons

  20. Charge (+) Mass is equal to 1 atomic mass unit (amu) Found in the nucleus Identifies the element/atom Protons

  21. Charge (0) – neutral Mass is equal to 1amu Found in the nucleus Helps determine mass Neutrons

  22. Charge is negative (-) Mass is equal to 0 amu Found outside the nucleus, in the electron cloud Electrons

  23. Energy levels • 1st level holds up to 2 e- • 2nd level holds up to 8 e- • 3rd level holds up to 8 or 18 e- • 4th level holds up to 8, 18, or 32 e- • Outer Level holds up to 8 e- (called valence electrons)

  24. Valence Electron • The number of electrons in the outermost electron shell. • Most important

  25. Oct 6, 2014 • Objective: Quantify atoms and ions based on subatomic particles • Do Now: How many valence e- will the following elements have? (Draw out your energy orbitals with the “nucleus” in the center to show work) • Carbon • Na • Hydrogen • Chlorine

  26. A Guided Tour of the Periodic Table 3.2 https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=meet%20the%20elements Meet the Elements

  27. Periodic Law • Properties of elements tend to change in a regular pattern when elements are arranged in order of increasing atomic number.

  28. Periodic Law • Periodic Table is set up by increasing atomic number. • Atomic Number is the # of protons in the atom.

  29. Average Atomic Mass

  30. Atomic Number • tells you number of protons • Never Changes for an atom. • Appears as a whole # on the periodic table. • No two elements can have same atomic #.

  31. Atomic Number Atomic Number # of protons

  32. Mass Number • The mass of an atom • Total number of protons plus neutrons in the nucleus of a single atom. • Atoms of the same element won’t always have the same mass number

  33. Mass Number # of neutrons Mass # # of protons

  34. Isotopes • Any atoms having the same number of protons but different number of neutrons. • So they also have different mass numbers.

  35. Average Atomic Mass • Average mass of all known isotopes for an element • Found on the periodic table as a number with a decimal

  36. Atom’s Charge • They are neutral. • All atoms have the same number of protons and electrons. • Charges cancel each other out.

  37. Ions • Charged particles. • Form when atoms lose or gain electrons. • They do this so the ions have a full outer shell • Two Types.

  38. Cations • Positively charged ions. • Form when atoms lose electrons. • Metals • Left side of table

  39. Cations • # of protons greater than # of electrons • More (+) than (-)

  40. Na Atom Na+ Cation

  41. Anions • Negatively charged ions. • Form when atoms gain electrons. • Nonmetals • Right side of table

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