Chapter 3: Atoms Flashcards
Who thought matter was continuous?
Aristotle
Who thought of indivisible “atomos?”
Democritus
Who first called particles atomos, from which we get out word atom?
Democritus
Who believed that atoms were spheres surrounded by heat envelopes?
Dalton
Who thought atoms were indivisible and cannot be destroyed?
Dalton
Who first suggested that elements are made of atoms and that the atoms of an element are alike?
Dalton
Who proposed that atoms are hard spheres of different sizes and masses?
Dalton
According to his research with Crookes tubes, which scientist suggested that the cathode rays were made of negatively charged particles?
Thompson
Who first proved that atoms were divisible when he saw evidence of charged particles existing in the atom?
Thompson
What is Thomson’s atomic model called?
Plum Pudding Model
The discovery of electrons demonstrated that atoms are not what?
Indivisble
Most of an atom consists of what?
Empty space
Who developed the nuclear model?
Thompson
Who developed the plum pudding model?
Thomspon
Who developed the Saturnian model?
Nagaoka
In Rutherford’s experiments a beam of what was directed at a piece of gold foil?
Alpha particle emmiter
What was not an observation that led Rutherford to believe that most of the atom’s mass and positive charges were densely packed into a very small space?
Some alpha particles emitted protons as they fell back to their original energy levels
The Bohr model suggests that electrons move how?
Energy levels
What are two reasons that Bohr model is still in widespread use today?
It’s simple and represents energy levels that are easier to visualize.
Who believed that electrons moved through spherical regions located a fixed distance from the nucleus?
Bohr
What is the currently accepted model of the atom?
Quantum mechanical model
Electrons in the quantum-mechanical model occupy what?
Orbitals
The quantity of what subatomic particle in an atom of a substance determines the atom’s identity?
Proton
What subatomic particle is the smallest of the three subatomic particles?
Electron
The ______ is about 1836 times the mass of an electron.
proton
The slightly more massive ______ is about 1838 times the mass of an electron.
neutron
Potassium-39 and potassium-41 always have the same number of what?
Protons
What subatomic particle has a charge of -1e?
Electron
Copper-63 and copper-65 can never have the same number of what?
Neutron
What subatomic particle is found in the nucleus and has no electrical charge?
Neutron
What subatomic particle has a charge of +1e?
Proton
An anion has more what than protons?
Electrons
A cation has more what than electrons?
Protons
Ions are atoms that have unequal numbers of what?
Electrons or protons
An anion has a negative charge because why?
It gained electrons or lost protons.
Which of these are typically represented with whole numbers - atomic mass, atomic number, or mass number?
Atomic number and mass number
Which of the following is a weighted average - atomic mass, atomic number, or mass number?
Atomic mass
Thompson discovered the existence of ________.
electrons
What term means an atom of an element with a different mass?
Isotope
What term means number of protons?
Atomic number
What term means protons plus neutrons?
Mass number
What is a cathode ray?
A stream of negatively charged particles.
What was not in Rutherford’s model?
Neutrons
Who was the first scientist to say that the atom is divisible?
Thompson
