Atomic Structure and the Periodic Table of the Elements Flashcards
Dalton’s five basic ideas about atoms
(helium nucleus 4/2 He) Positively charged, 2+
Ex. 230/90 Th –> 4/2 He + 226/88 Ra
- All matter is made up of very small, discrete particles called atoms 2. All atoms of an element are alike in weight, and this weight is different from that of any other kind of atom. 3. Atoms cannot be subdivided, created, or destroyed 4. Atoms of different elements combine in simple whole-number ratios to form chemical compounds. 5. In chemical reactions, atoms are combined, separated, or rearranged
Niels Bohr
Published a theory explaining the line spectrum of hydrogen. He proposed a PLANETARY MODEL that quantized the energy of electrons to specific orbits. Louis de Broglie and others showed that quantum theory described a more PROBABILISTIC MODEL of where the electrons could be found that resulted in the theory of orbitals.
J. J. Thomson
Discovered the electron and ratio of the electrical charge the electron to its mass Using a cathode ray - beam was deflected because it was magnetics and electrical
Robert Millikan
Experiment determined the mass of an electron - Oil drop experiment
Ernest Rutherford
Gold foil experiment using alpha particles confirmed that there was mostly empty space between the nucleus and electron
James Chadwick
Discovered the neutron
Bohr Model of the Atom
Electron distribution to principal energy levels has the formula: 2n^2 Principal Energy Level –> Max. Number of Electrons (2n^2) 1 –> 2 2 –> 8 3 –> 18 4 –> 32 5 –> 50
Nucleons
Proton and neutrons are in the nucleus. These particles are known as nucleons.
atomic number
The number of protons in the nucleus
Henry Moseley
First determined the atomic number of the elements through the use of X-ray
Mass number
sum of protons and neutrons in the nucleus
Average atomic mass
The weighted average of the atomic masses of the naturally occurring isotopes of an element
Calculating Average Atomic Mass
69.17% copper-63 –> atomic mass of 62.919 30.83% copper-65 –> atomic mass of 64.93 (0.6917 x 62.919) + (0.3083 x 64.93) = ANSWER
Valence electrons
The electrons found on the outer-most energy level
Lewis Structure
A Lewis strucutre shows the atomic symbol to represent the nucleus and inner shell electrons. It shows dots to represent the valence electrons.
Change in energy (DELTA E)
DELTA E = Efinal - Einitial
Photons
discrete radiant energy
Atomic Spectra Chart
Lyman series: When an electron cascades from a level higher than the first level down to n = 1 (ultraviolet range) Balmer series: n = 2 (visible range) Paschen series: n = 3
Spectra
(spectroscope) distinct color line