lect_3oct1f09

lect_3oct1f09 - Outline 3 1-OCT-2009 1. Review a....

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Outline 3 1-OCT-2009 1. Review a. Electrons, Nuclei, Protons, Neutrons (Thompson, Milliken, Rutherford, Chadwick) b. A Z X , nuclides, isotopes SKILL: Write and interpret nuclide symbols 2. Atomic Mass Isotopic Abundance & Mass; SKILL: Get atomic mass from isotopic mass and fractional abundance. Examples 3. Periodic Table Period and Group (Family) 4. Compounds- Ionic (exchange e - ), Covalent (share e - )
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Despite Dalton’s postulates of indivisibility, experiments (late 1800’s & early 1900’s) showed atoms themselves consist of particles . Mostly empty space Nucleus (core): + charge, has most of mass, contains protons and neutrons. Electrons: - charge, very small mass. Protons: + charge Evidence for these were given in previous lecture. Explains why we know what we know! Atomic Structure (Review) Structure of Atom (Nuclear Model)
Background image of page 2
3 Electron Evidence (Review) Experiment: Examine cathode rays with electric and magnetic fields. ( J. J. Thomson Charge/mass: m e /e =5.686*10 12 kg/C Rays produced by all metals (so in all elements) Rays bend away from negative plate (so – charge). Charge = - 1.602*10 -19 C (Millikan)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Nucleus Evidence (Review) Experiment: Alpha particle ( + charge) scattered by thin metal foil experiments ( Geiger and Marsden) Observation: Most particles went straight through foil Interpretation: mostly empty space ( Rutherford). Observation: Some were scattered Interpretation: some + charged particles (Rutherford).
Background image of page 4
5 Proton Evidence (Review) Experiment : Examine canal rays in cathode ray tubes. Rays move opposite direction to cathode rays and bend toward negative plate (so + charge). Smallest mass to charge ratio (m/e) occurs with hydrogen in tube; mass ~1800 * m e (so smallest + charged particle).
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Neutron Evidence: Review Experiment: Beryllium metal bombarded by alpha particles (saw these in slide 20). British Physicist James Chadwick (1932). Observation : Strongly penetrating radiation is emitted by Beryllium. Interpretation : Strong penetration implies uncharged particle. Further studies : This particle has almost same mass as proton, mass ~1800 * m e .
Background image of page 6
7 Element - substance whose atoms all have same atomic number , Z. Atomic number ( Z ) - Number of protons in nucleus of atom = # electrons in neutral atom. Proton - nuclear particle with positive charge equal to that of e -’ s (“unit” charge) and mass more than 1800 times that of e - ’s. Summary: Atomic Structure (1) Nuclear structure
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
8 Neutron- nuclear particle with mass almost identical to that of proton, but zero electric charge . Mass number
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 42

lect_3oct1f09 - Outline 3 1-OCT-2009 1. Review a....

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online