chapter 4 atomic r outline - cardozohigh.enschool.org
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1
The Gold Foil Experiment
Most of the particles passed through, some are deflected.
ATOMIC STRUCTURE Reference Table: Periodic Table, Table O 1. Models of the atom:
A. Dalton: tiny, indestructible particles with no internal structure.
B. J.J. Thomson: plum pudding model electrons embedded in a positive atom.
C. Rutherford Model of the atom: most of the atom is empty space with small, dense positively charged nucleus.
D. Bohr’s model of the atom stated that the electrons traveled in certain orbits.
E. The Quantum Mechanical Model:
2. Structure of the atom: PEN
• Proton: positive charged; 1 amu • Neutron: neutral; 1 am • Electron: negative charged; 1/1836 amu
3. The charge of the atom is neutral. The nucleus is
positive. 4. Nucleon: particles found in the nucleus (protons and
neutrons) 5. Nucleus: contains most of the mass of the atom, has a
positive charge. The number of protons is called the nuclear charge.
6. 1 amu: the atomic mass unit; base on 1/12 the mass of a
carbon 12 atom. 7. Atomic number: the number of protons in an atom; used
to identify the element. 23 Atomic number à 11 Na 8. Mass number: See the periodic table. Mass number à 23 11 Na 9. Number of neutrons= mass number – atomic number mass number 23 atomic number - 11 Na 12 10. The Ground state: the lowest and most stable, energy
state of an atom. See periodic table 7 3 Li 2-1 11. Excited state: Absorption of energy will cause electrons
to temporarily jump to higher energy levels and when the electrons fall back down to lower levels they emit energy in the form of light.
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3 Li 1-2
Present: the Quantum Mechanical Model
Bohr 1913
Rutherford 1909
J.J. Thomson 1897
msm
Dalton 1803
α
_-‐=_
2
Na 2-‐8-‐1
12. How does an electron become excited?
13. Isotopes: same element, same atomic number, but
different number of neutrons and mass number. Mass Number 16 17 18
atomic number - 8 O - 8 O - 8 O neutrons 8 9 10 99.76% 0.04 % 0.20 % the number of neutrons = mass number – atomic number 14. Atomic mass: the average of the atomic mass of the
naturally occurring isotopes.
Isotope % Abundance Mass (amu) Boron-10 19.78 10.013 Boron-11 80.22 11.009
Atomic mass = (19.78 X 10.013) + (80.22 x 11.009)
100 100
Atomic mass = 1.9805 + 8.831 Atomic mass= 10.81 a.m.u.
15. Valence electron:
• electrons in the outermost shell 16. Lewis Electron Dot: represent the valence electron. Na ● 17. Draw the electron configuration of Na: 2-8-1
18. Spectroscope: An instrument that breaks light into colored bands
19. The visible spectrum is that part of the electromagnetic
spectrum that is visible to the eye, generally with wavelengths ranging between about 400 and 700 nm.
20. The Electromagnetic Spectrum:
21. Type of Spectra:
a) Continuous Spectrum: Separation of light by a
prism according to wavelength
Valence electron: 1
Kernel: nucleus + 2-‐8
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b) Bright-Line Spectra or Fingerprints of Elements: Each element has its own distinct line spectra made up of only the lines of specific wavelength that correspond to its atomic structure.
21. Examine the spectra below. The bottom spectrum is a mixture of two or more of the
elements above it. Which elements are present in the mixture?
Answer: ____________________________________
23. Flame Test:
Every element absorbs and emits different amounts of energy
Lithium Calcium