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Chemistry

Terms in this set (31)

First person to say that matter wasn't infinitely divisible, but made up of individual particles, called atomos.
Democritus
Disagreed with Democritus because he didn't believe that empty space could exist
Aristotle
____________Revived the idea of the atom in the early 1800's based on numerous chemical reactions.
John Dalton
______________-explained conservation of mass in a reaction as the result of the combination, separation, or rearrangement of atoms.
Daltons Atomic Theory
The smallest particle of an element that retains the properties of the element is called an-_____________
Atom
When an electric charge is applied, a ray or radiation travels from the cathode to the anode, called a ____________________.
Cathode Ray
___________ are a stream of particles carrying a negative charge
Cathode Rays
The parts carrying a negative charge are known as -_____________.
Electrons
Who discovered electrons?
J.J. Thompson
In the early 1910s, ________________used the oil-drop apparatus to detect the charge of an electron.
Robert Milikan
In 1911, ___________________ studied how positively charged alpha particles interacted with solid matter.
Ernest Rutherford
_____________ concluded that atoms are mostly empty space
Rutherford
Almost all of the atoms positive charge and almost all of its mass is contained in a dense region in the center of the atom called the________________.
Nucleus
Chemical behavior can be explained by considering only an atoms _____________.
Electron
The number of protons in the nucleus of an atom identifies the element and is known as the elements -____________.
Atomic Number
Atoms with the same number of protons, but different numbers of neutrons are-_____________.
Isotopes
In _______________, most elements are found as mixtures of isotopes.
Nature
Isotopes containing more neutrons have a ________ mass.
Greater
The _____________ is the sum of the protons and neutrons in the nucleus.
Mass Number
One ________________________(____) is defined as 1/12th the mass of a carbon-12 atom.
Atomic Mass Unit(AMO_
The ____________ of an element is the weighted average mass of the isotopes of that element.
Atomic Mass
_____________ can change one element into another element.
Nuclear Reactions
In the late 1890s, Scientists noticed some substances spontaneously emited radiation, a process they called -______________.
Radioactivity
The rays and particles emited are called _______.
Radiation
A reaction that involves a change in an atoms nucleus is called a ____________.
Nuclear Reaction
Unstable nuclei lose energy by emitting radiation in a spontaneous process called ______________.
Radioactive Decay
Alpha Radiation is made up of positively charged particles called -_______________.
Alpha Particles
Each alpha particle contains two protons and two neutrons and have a ________ charge.
2+
______________--Radiation that has a negative charge and emits beta particles.
Beta Radiation
______________-Are high-energy radiation with no mass and are neutral.
Gamma Ray
Each _____________ is an electron with a 1- charge.
Beta Particle
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