Atom Presentation Flashcards
What is the significance of Democritus (400 BC) when it comes to the history of the atom?
First person to use the term “atom”;
Made the theory of the universe
What is the significance of Aristotle when it comes to the history of the atom?
Believed that empty space did not exist;
Believed that matter was made up of earth, fire, and water
What is the significance of Dalton (1800’s) when it comes to the history of the atom?
He marked the beginning of the atomic theory
What is the atom?
The fundamental or basic unit
What is the significance of J.J. Thomson (1890’s) in the history of the atom?
Credited for discovering the electron by using the cathode ray tube
What is the significance of Rutherford (1910’s) in the history of the atom?
Discovered the nucleus and the fact that electrons orbit around the nucleus by his Gold Foil experiment
What is the significance of Bohr (1910’s) in the history of the atom?
Perfected Rutherford’s model;
Answered why the electrons did not collapse into the nucleus
Who (inadvertently) discovered the cathode ray tube?
William Crookes
From what side to what side does the cathode ray travel?
Travels from the cathode to the anode
Will the (cathode ray) beam always travel straight?
Yes
What did Thomson predict the mass of the negative charge to be?
Charge was 1000 times lighter than that of a hydrogen atom
What happened in the Gold Foil Experiment?
Rutherford shot a beam of positively charged alpha particles;
Most of the particles did no deflect at all (every now and then, a particle would deflect all the way back)
What did Rutherford conclude from his experiment?
That there must be a positive center of the foil;
He called this center the nucleus
Who created the planetary model of the atom?
Rutherford
What is radiation?
When an electron moves from one level to another
Describe Bohr’s atomic model.
Electrons orbit the nucleus in a way that has a set size and energy;
The lower the energy of the electron, the lower the orbit;
If that energy level is filled, a new energy level will begin
How many electrons can each orbital contain?
2 (two)
How do atoms of different elements differ in the periodic table?
Atomic number (the number of protos in an atom);
Chemical symbol
How much do protons and neutrons weigh approximately?
1.67 x 10^24 g
How much does an electron weigh?
1/1840 of a neutron
How much does an atomic mass unit weigh?
1/12 the mass of a carbon-12 atom
How can one calculate atomic mass?
By multiplying: (mass of isotope)(percent abundance)
