# 17 1 Atom by 62I0JCj

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```									17.1 Atomic Structure

*no need to write italicized notes
Atoms
   Determine the properties of all matter (ie.
Air/clothes/chair)
   Atoms of the same element are exactly alike
   Atoms combine with others to form molecules
Cathode Ray/Plum Pudding
   Ernst Rutherford: Gold Foil
Experiment=Discovery of the nucleus (+)
   It was quite the most incredible event that has ever happened to me
in my life. It was almost as incredible as if you fired a 15-inch shell at
a piece of tissue paper and it came back and hit you. On
consideration, I realized that this scattering backward must be the
result of a single collision, and when I made calculations I saw that it
was impossible to get anything of that order of magnitude unless
you took a system in which the greater part of the mass of the atom
was concentrated in a minute nucleus. It was then that I had the
idea of an atom with a minute massive center, carrying a
charge.[2]—Ernest Rutherford
History of an Atom
   4th century B.C. Democritus made atom up. VERY
hard to prove.
   1808-John Dalton- Atomic Theory
   1.) all elements have different atoms
   2.) Atoms link to other atom
   3. )Molecules or Compounds

   1900’s- atoms can be split into other parts…….
   Quarks: 3-p & 3-n
Composition
   Protons:+charge
   Neutrons: = charge
   Nucleus: Protons + Neutrons (+ charge)
   Electrons: - charge, moving outside nucleus
   Atoms overall neutral b/c same # of protons
as electrons

   # Protons determine the element- Atomic #
Atom Models
   1913- Niel Bohr- electrons move in set
orbits= energy levels.
   Can gain/lose energy to change E. Level
   1925-electrons move quickly=electron cloud
(orbitals)
   4 orbitals= s (sphere), p (dumbbell), d , f
(both variety)
   Valence electron- outermost
Bill Nye Loves Atoms
Periodic Table
   Periods = 7
   Group= 18

   4 shapes of atoms: S, P, D, F

   Lose or gain Neutron= isotope

   Lose or gain electrons= Ionization
   Gain Electron- anion
   Lose Electron- cation
17.2 Masses of Atoms
   Electrons VERY small-no mass
   Protons/neutrons = 1.6726 x 10-24g=1 amu

   Atomic #=# of protons=Identifies the element
   (Average) Atomic Mass=P+N=nucleus
   # neutrons= mass # - proton #

   Isotopes
The Atom
   Protons= 1800 times as big as electrons
   Electron CloudEmpty Space
   Atomic #=Protons
   Atomic Mass: Protons + Neutrons
   P and/or N mass= 1 u= 1/12 mass of C
   1 amu=1.67 e-27 kg
   Actual Mass: A x u
   Isotope=different masses=Same P/Differ N
   Nuclide= nucleus of isotope
   Strong Nuclear Force=Keeps nucleons together
   Electromagnetic Force= Keeps Nucleus and E
together

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