Exam Flashcards
(16 cards)
Who was the first person to believe that matter was made up of smaller particles?
Democritus
Was Democritus supported? Why or why not?
No
Why did it take nearly 2,000 years before anyone developed the idea of smaller particles further?
It took nearly 2,000 years for the idea of smaller particles to be developed further because the ancient Greek philosopher Aristotle, who was highly influential, rejected the atomic theory proposed by Democritus, leading to the widespread acceptance of Aristotle’s view that matter could be infinitely divided, effectively halting further exploration of the concept for centuries until advancements in technology allowed for experimental verification of the atomic theory
Who developed the atomic theory?
Dalton
What is the first statement of the atomic theory?
all matter is composed of extremely small particles called atoms
What are the two modifications that have been made to the atomic theory?
- atoms are not indivisible, but are composed of smaller subatomic particles like protons, neutrons, and electrons; and 2. atoms of the same element can have slightly different masses due to the existence of isotopes with varying numbers of neutrons
Define atom. Can we see atoms?
The smallest part of a substance that cannot be broken down chemically. no
Who discovered that subatomic particles existed by performing the cathode ray experiment?
J.J. Thomson
How did scientists determine that the cathode ray was composed of negatively charged particles?
by observing how it deflected in an electric field
Draw and label Thompson’s plum pudding model of the atom.
What surprised scientists when observing the gold foil experiment?
Draw and label Rutherford’s nuclear atomic model of the atom.
What are the three subatomic particles that make up the atom? Include their charge and location in the atom for each.
The number of protons in an atom can also be called the ____________
- The total number of protons and neutrons can also be called the ___________ ____________.
