Chemistry Flashcards
Basic atomic structure
The three particles of the atom are:
Protons, neutrons, and electrons.
Their respective charges are:
Positive, neutral, and negative.
The number of protons in one atom of an element determines the atom’s ____, and the number of electrons determines the _____ of the element.
atomic number, charge.
The atomic number tells you the number of ____ in one atom of an element. It also tells you the number of ____ in a neutral atom of that element. The atomic number gives the “identity” of an element as well as its location on the periodic table. No two different elements will have the ___ atomic number.
protons, electrons, same.
The _______ of an element is the average mass of an element’s naturally occurring atom, or isotopes, taking into account the ___ of each isotope.
average atomic weight, mass.
The ______ of an element is the total number of protons and neutrons in the ____ of an atom.
mass number, nucleus .
The mass number is used to calculate the number of ____ in one atom of an element. In order to calculate the number of neutrons you must subtract the ____ from the ____.
neutrons, protons, mass number.
The symbol and number of protons in Lithium:
Li, 3.
The symbol of and the number of electrons in a neutral atom of Uranium:
U, 92.
The symbol of and the number of neutrons in an atom of Barium:
Ba,81.
JJ Thomson
confirmed existence of neutrons
Ernest Rutherford
first suggested the presence of atoms and named them atomos
James Chadwick
developed the beginnings of the modern atomic theory in the 1800’s
STM
gave scientists first image of individual atoms
Democritus
used cathode ray tube to discover electrons
