Module 3: Atomic Theory Flashcards
philosophers during the 5th century that said all matter was composed of small, finite particles, that they called atomos
Leucippus and Democritus
meaning of atomos
indivisible
philosopher that said matter is the “four elements” and could be infinitely divided; held sway over for over 2000 years
Aristotle
he revolutionized chemistry with his hypothesis that the behavior of matter could be explained using an atomic theory
John Dalton
when did John Dalton published his postulates about his atomic theory
1807
also called the law of constant composition
Law of Definite Proportions
This law states that all samples of a pure compound contain the same element in the same proportion
Law of Definite Proportions
This law states that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other elements in a ration of small, whole numbers
Law of Multiple Proportions
This law states that 2 elements that form 2 different compounds will have different ratio of the elements
Law of Multiple Proportions
the experiment of J. J. Thomson
Cathode Ray Experiments
cathode ray particles are known as what now?
Electrons
who discovered the charge to mass ratio of an electron
J.J. Thomson
the experiment of Robert A. Millikan
Oil Drop Experiment
In 1909, he was able to determine the charge of a single electron
Robert A. Millikan
charge to mass ratio of an electron
1.759 x 10e11 C/kg
charge of a single electron
1.5 x 10e-19
In 1904, he proposed the “plum pudding” model which described a positively charged mass with an equal amount of negative charge in the form of electrons embedded in it
J.J. Thomson
the experiment of Ernest Rutherford
Gold-foil experiment
he performed a series of experiments using a beam of high-speed, positively charged alpha particles that were produced by radioactive decay of radium
Ernest Rutherford
He discovered that the volume occupied by an atom consist of a large amount of empty space and the center is a small, heavy positively charged body
Ernest Rutherford
He discovered electrons
J.J. Thomson
He discovered protons
Ernest Rutherford
He found evidences of neutrons in 1932, uncharged subatomic particles with mas approximately the same as that of protons
James Chadwick
Theory that state that an atom contains a very small nucleus composed of protons and neutrons surrounded by a much larger volume of space containing electrons
Modern Atomic Theory
the unit of mass that is used for masses of atoms, molecules, and subatomic particles
Atomic mass unit (amu)
This is defined with regard to the most abundant isotope of carbon (Carbon-12)
Atomic mass unit (amu)
1 amu is equivalent to how many grams?
1.6606 x e-24 g
Does the fundamental unit of charge equals the charge of an electron?
yes
Fundamental unit of charge of an electron
e = 1.602 x 10e-19
The number of protons in the nucleus of an atom
Atomic Number (Z)
Its value determine the identitiy of the atom
Atomic Number (Z)
The total number of protons and neutrons
Mass Number (A)
formula for number of neutrons
A - Z
