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Chemistry Ch. 11

What did Democritus, Dalton, Thomson,Rutherford, and Bohr all have in common? They each contributed to the development of the atomic theory.
In Thomson's plum-pudding model of the atom, the plums represent what? Electrons
An atom of gold with 79 protons, 79 electrons, and 118 neutrons would have a mass number of? 197
Which of the following has the least mass? Electron
If an isotope of uranium, uranium-235, has 92 protons, how many protons does uranium-238 have? 95
How did Democritus describe atoms? A single material with one shape and size.
What is the smallest particle into which an element can be divided and still be the same substance? Atom
Particle that cannot be cut Atom
Negatively charged particle discovered by Thomson Electron
Central region of the atom Nucleus
Region where electrons are likely to be found Electron cloud
Particle in the center of an atom that has no charge Neutron
Subatomic particle that has a positive charge Proton
A unit of mass that describes the mass of an atom or molecule Atomic Mass Unit
Atom that has the same number of protons but different number of neutrons Isotope
The sum of protons and neutrons in an atom Mass number
How was Bohr's theory of atomic structure similar to and different from the current theory? Bohr said there was no certain path for electrons, and in the current theory, the exact path cannot be predicted. But there is an electron cloud.
Describe atomic number and the atomic mass and explain the difference. Atomic number tells how many protons are in the nucleus of an atom, while atomic mass tells the mass of an atom or molecule.
What was one of Dalton's ideas? All substances are made of atoms
What is the meaning of atom? Not able to be divided
Which statement about isotopes is true? They have the same number of protons
According to Rutherford, what was in the center of an atom? Nucleus
Which phrase describes radioactive isotopes? They are unstable
Which of the following has the least mass in an atom? Electron
Thomson discovered the negatively charged particles called Electrons
Rutherford believed that each atom has a Nucleus
The current atomic theory includes the _ model. Electron cloud
All substances are made of Atoms
Isotopes always have the same number of Protons
Most elements have a mixture of two or more
Protons stay together in the nucleus because of _ force. Strong
Objects are pulled toward one another by _ force. gravitational
Electrons around the nucleus are held in place by _ force. electromagnetic
Created by: itslizzie143