Unit 4 Atomic History Flashcards
1
Q
Democritus
A
- Proposed the idea of atoms as the smallest undividiable particle of a substance.
- Stated that all the universe is composed of two elements: the atoms and the void in which they exist
2
Q
John Dalton
A
- Developed an “atomic theory” with spherical solid atoms based upon measurable properties of mass
- Atoms make up everything and cannot be created or destroyed.
- Atoms of an element are identical.
- Atoms are rearranged in chemical reactions to form different substances.
3
Q
Sir William Crookes
A
- Discovered
- cathode rays travel in straight lines
- cause glass to fluoresce
- give a negative charge to objects they strike
4
Q
J.J. Thomson
A
- Discovered/proved the electron
- Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram
- Also studied “canal rays” and found they were associated with the proton ( H+)
5
Q
Ernest Rutherford
A
- Studied radiations emitted from uranium and thorium and named them alpha and beta
- Gold Foil experiement
- Using alpha particles as atomic bullets, discovered the nucleus and established that the nucleus was
- very dense
- very small
- positively charged
- Disproved the Plum Pudding Model (assumed that the electrons were located outside the nucleus)
6
Q
Max Planck
A
- used the idea of quanta (discrete units of energy) to explain hot glowing matter
7
Q
Hantaro Nagaoka
A
- Proposed a “Saturnian” model of the atom with flat rings of electrons revolving around a positively charged particle
8
Q
R.A. Millikan
A
- Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron.
9
Q
H.G.J. Moseley
A
- Using x-ray tubes, determined the charges on the nuclei of most atoms
- wrote “The atomic number of an element is equal to the number of protons in the nucleus”
10
Q
Niels Bohr
A
- Developed an explanation of atomic structure that underlies regularities of the periodic table of elements;
- Developed Bohr model (planetary model) - had atoms built up of sucessive orbital shells of electrons
- Proposed energy levels for electrons
11
Q
Louis de Broglie
A
- Discovered that electrons had a dual nature-similar to both particles and waves (Particle/wave duality)
12
Q
Werner Heisenberg
A
- Described atoms by means of formula connected to the frequencies of spectral lines.
- Proposed Principle of Indeterminancy (Heisenberg Uncertainty Principle) - you can not know both the position and velocity of a particle
13
Q
Erwin Schrodinger
A
- Viewed electrons as continuous clouds
- Introduced “wave mechanics” as a mathematical model of the atom
14
Q
James Chadwick
A
- Using alpha particles discovered the neutron
15
Q
s sublevel
A
Has one orbital
Present on every energy level
16
Q
p sublevel
A
3 orbitals
appears for the first time on 2nd energy level
17
Q
d sublevel
A
5 orbitals
appears for the first time on 3rd energy level
always fills after the s on the level above (4s and then 3d)
18
Q
f sublevel
A
7 orbitals
appears for the first time on 4th energy level
fills after the s orbital two energy levels above
(4f fills immediately after 6s)
