Subatomic Particles
The average atomic mass of an atom is determined by
the weighted average of each naturally occurring isotope
Developed the theory that electrons are in orbitals or distinct energy levels outside the nucleus.
Who is Bohr?
2 ways isotopes are distinct from each other
They have different #'s of neutrons; their masses are different
Greek philosopher who declared that all matter was made of tiny indivisible particles called atoms
Who is Democritus?
The Law that states that a chemical compound always contains the same elements in the exact same proportions by mass?
What is the law of definite proportions?
The scientist responsible for discovering the charge on an electron & the name of the experiment
Who is Robert Milikan? oil drop experiment
The periodic table that can be used to determine the number of protons in an atom.
What is the atomic number?
This scientist discovered the existence of neutrons.
Who is James Chadwick?
Determine the identity of the atom
What is the [number of] proton?
How a mole is defined (NOT the value)
The number of atoms in 12 grams of carbon-12
Developed principles of atomic theory
Dalton
What is term for the number "35.45" for chlorine (on the periodic table)?
What is its average atomic mass.
What is Avogadro's number [word and value]?
A mole, equal to 6.022 x 1023
The mass number is determined by
What is the number of protons and neutrons in a particle?
These particles are responsible for the properties of an atom.
What is the electrons?
Three discoveries by Rutherford, and the name of his experiment.
Gold foil experiment --> protons; dense nucleus; that atom is mostly empty space.
The isotope name and symbol for an element with 20 protons and 22 neutrons.
What is Calcium - 42 and 42Ca ?
How you can know the molar mass of an element.
It is numerically equivalent to the element's average atomic mass in atomic mass units (a.m.u.'s) - found on the periodic table.
a particle with a negligible mass (mass number = 0)
What is the electron?
Law that states atoms combine in small whole-number ratios; give an example
Law of multiple Proportions: NO and NO2
Discoverer of electrons, and the name of his model.
Who is JJ Thomson; plum-pudding.
Mass number, atomic number, and isotope symbol for an atom with 34 protons and 44 neutrons
A = 78; Z = 34; 78Se
2 postulates of Dalton's atomic theory that are no longer considered valid.
What are
1) All atoms of the same element are identical [have the same mass]
2) Atoms cannot be subdivided, created or destroyed.