2.1 - 2.2 + Chp 19 Test Flashcards
Who is the Father of the Atomic Theory
John Dalton
The term “atomos” first spoken by the Greek philospher Democritus, means:
“uncuttable” or “indivisible”
What does the Modern Atomic Theory state? Write 2 out of 3 parts
a. all matter is composed of atoms
b. atoms of the same element are the same; atoms of different elements are different
c. atoms combine in whole-number ratios to form compunds
What happens to atoms during a chemical change? What can’t or doesn’t happen?
Atoms rearrange because they cannot be created or destroyed during a chemical change
the law of conservation of mass states:
in a chemical change mass and atoms are preserved –> stay the same
the Law of Definite Proportions (constant composition) states
the ratio of atoms and their masses in a compound are the same
the ratio of atoms in molecule of H2O is:
1:2
What did J.J. Thomson discover
Electrons
What is the charge of an electron, and what evidence is there that showed this
negative charge, the evidence to show that there is negative charge was through the cathode ray and the beam of energy would attract to a positive charge but repel to a negative charge
who determined that atoms have a nuclear structure
ernest rutherford
what is the charge of an alpha particle
positive
describe what happened to the alpha particles that was surprising in the gold foil experiment
most of the alpha particles were indeed not deflected, a very small percentage (about 1 in 8000 particles) bounced off the gold foil at very large angles, some were even redirected back toward the source
how did rutherford know that the nucleus was positively charged
he knew alpha particles were positive, and since they were repelled when they hit the nucleus, the nucleus had to be positive
how does the size of the nucleus compare with the size of the entire atom
the nucleus takes up a small portion of the atom
where is almost all the mass of the atom located
the nucleus of the atom (protons and neutrons together)
nuclear symbol: 120/51 Sb +4
charge: __
protons: __
neutrons: __
electrons: __
charge: +4
protons: 51
neutrons: 69
electrons: 47
