Atoms Flashcards
The fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound
Law of definite proportions
If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers
Law of multiple proportions
Dalton’s atomic theory
- All matter is composed of extremely small particles called atoms
- Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties
- Atoms cannot be subdivided, created, or destroyed
- Atoms of different elements combined in simple whole-number ratios to form chemical compounds
- In chemical reactions, atoms are combined, separated, or rearranged
Who discovered the electron?
JJ Thompson
In a cathode ray, which direction do electrons move?
The ray traveled from the cathode to the anode when the current was passed through the tube.
Who discovered how to measure the charge of an electron?
Robert A. Millikan
Who discovered the atomic nucleus?
Earnest Rutherford
What did Earnest Rutherford’s experiments Discover?
The results of his gold foil experiment led to the discovery of a very densely packed bundle of matter with a positive electric charge (the nucleus)
What is an isotope?
And atom with a different number of neutrons
What is the first energy level and how much does a hold?
The “K” shell
Can only hold two electrons
What are the three isotopes of hydrogen?
Protium
Deuterium
Tritium
How would you write do Deuterium in hyphen notation?
H-2
When writing nuclear symbol for tritium, what number goes on top and which one goes on bottom?
Atomic mass on top
Atomic number on bottom
(Charge is on bottom if talking about a sub-atomic particle)
