chem 4
John Dalton
In a chemical reaction, atoms are separated, combined or rearranged
1/12 the mass of a carbon-12 atom
One atomic mass unit is...
false
true or false? Ancient philosophers regularly preformed controlled experiments.
true
true or false? Both Democritus and Dalton suggested that matter is made up of atoms.
true
true or false? Dalton thought that all atoms of a specific element have the same mass.
false
true or false? Daltons atomic theory stated that matter is mostly empty space.
true
true or false? Philosophers formulated explanations about the nature of matter based on their own expiriences
protons, electrons, and atomic number
what isotopes are all equal?
Rutherford
Proposed the nuclear atomic model
Thomson
Calculated the mass of an electron
mass number
sum of the atomic number and neutrons in the nucleus
Democritus
believed matter was made up of tiny individual particles called atomos
51 protons, 51 electrons, 72 neutrons
An isotope has an atomic number 51 and a mass number 123
John Dalton
Atoms are indivisible and indistructible
John Dalton
Atoms of a given element are identical in size, mass, and chemical properties.
John Dalton
Atoms of a specific element are different from those of other elements
isotopes
Atoms with the same number of protons but different numbers of neutrons are called isotopes
Millikan
Determined the mass-to-charge ratio of an electron
Democritus
Greek philosopher that was the first person to propose the idea that matter was not infinitely divisible.
Plum pudding model
J.J. Thomson proposed a model that did not last
John Dalton
Matter is composed of extremely small particles, called atoms
Aristotle
Matter is made of earth, fire, air, and water.
John Dalton
Revived and revised democritus' ideas based on the results of scientific research he conducted.
Democritus
Size, shape, and movement of atoms determine the properties of matter
neutron
Subatomic particle that has a mass nearly equal to that of a proton, but it carries non electric charge
133, 55 Cs
Symbolic notation of cesium-133
4,2 He
Symbolic notation of helium-4
22,10 Ne
Symbolic notation of neon-22
234,92 U
Symbolic notation of uranium-234
atomic number
The number of protons in an atom is referred to as the...
proton
a subatomic particle carrying a charge equal to but opposite that of an electron
Democritus
believed atoms could not be created, destroyed, or further divided.
Democritus
atoms are solid, homogeneous, indestructible, and indivisible
atomic mass unit
defined as 1/12 the mass of a carbon-12 atom
Aristotle
did not believe atoms moved through empty space
Aristotle
did not believe that empty space existed
John Dalton
different atoms combine in simple whole-number ratios to form compounds
Democritus
different kinds of atoms have different sizes and shapes
Democritus
his atomic theory was eventually rejected
atom
smallest particle of an element that retains the properties of the element is called an atom.
Democritus
matter is composed of atoms, which move through empty space
electron
negatively charged particles that are part of all forms of matter
atomic mass
part of an element that is the weighted average mass of the isotopes of that element
cathode ray
ray, originating from the cathode and traveling to the anode. A stream of negatively charged particles
