l22 - Today Announcements: HW#9 is due April 2 at 8:00 am...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
ISP209s8 Lecture 21 -1- Today • Announcements: – HW#9 is due April 2 at 8:00 am – Voting for the Spring Break Story contest is due April 2 at 8:00 am – HW#10 will be due April 9 at 8:00 am • Atoms and Nuclei
Background image of page 1

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

View Full DocumentRight Arrow Icon
ISP209s8 Lecture 21 -2- History • ca. Fourth century B.C.: Democritus proposes that matter is made of indivisible units called atoma . • 1896: Henri Becquerel discovers radioactivity by chance. • 1911: Ernest Rutherford discovers the nucleus. He found something hard and small at the center of atoms
Background image of page 2
ISP209s8 Lecture 21 -3- From Large to Small Atoms Atomic Nucleus A Proton Made of nuclei and electrons. Size: 10 -9 m Made of neutrons and protons. Size: 10 -14 m Made of quarks. Size: 10 -15 m A neutron has ddu quarks.
Background image of page 3

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

View Full DocumentRight Arrow Icon
ISP209s8 Lecture 21 -4- The Strong force at work Strong force actually is mostly the result of exchange of pairs of quarks. Looks like The probability of an interaction decreases exponentially with the mass of the exchanges particle. cm h t c range h t mc t E π 4 4 2 = Δ = Δ = Δ Δ
Background image of page 4
ISP209s8 Lecture 21 -5- The Nucleus • The nucleus contains more than 99.95% of an atom’s mass, but only 1E-15 of its volume! •T h e nucleons are held together by the strong force , even though the protons repel each other very strongly. 161 272 111 Rg Mass Number Atomic Number (or Proton Number) Neutron Number Element
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- Atomic Nuclei and Elements The number of protons determine the element (oxygen). The number of neutrons+protons determines the atomic mass (16 as shown). This nucleus is 16 O. The Chart of the
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/25/2008 for the course ISP 209 taught by Professor Sherrill during the Spring '07 term at Michigan State University.

Page1 / 21

l22 - Today Announcements: HW#9 is due April 2 at 8:00 am...

This preview shows document pages 1 - 7. Sign up to view the full document.

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