C1 Flashcards
Atom Definition
Smallest Part Of An Element That Can Exist
Molecule
Cluster Of Non-Metal Atoms Chemically Bonded Together
Element
Substance That Contains One Type Of Atom
Compound
Two Or More Elements Chemically Combined In Fixed Proportions.
Who first proposed the idea that the atom wa sthe smallest thing?
Democritus
What did Dalton’s evidence support?
The idea that atoms existed.
They were tiny spheres that couldn’t be divided.
What did JJ Thompson discover and when?
In 1897, he discovered that atoms are made up of smaller particles.
He then made his plum pudding model.
What was the Geiger-Marsden-Rutherford experiment?
Fired alpha particles (large positively charged particles) at very thin gold foil.
What were the results of the Geiger-Marsden-Rutherford experiment and what did they inidcate?
Most of the alpha particles went straight through the gold particles - Atoms are mainly empty space.
Some of the alpha particles were deflected - Center of an atom must have a positive charge.
Some of the alpha particles bounced straight back - Center of an atom must contain a great deal of mass.
What did Bohr propose and when?
In 1913, Electrons orbit the nucleus in fixed shells or orbitals located at set distances from the nucleus.
What did Chadwick prove and when?
Proved the existence of neutral particles called neutrons. 1932.
What are the relative masses of the subatomic particles?
Electrons - Negligible
Protons - 1
Neutrons - 1
What is the Atomic Number?
The number of Protons.
What is the Mass Number?
Number of Protons + Number of Neutrons
What determines what type of atom one is?
The number of protons.
What is the name of the outermost shell?
Valence Shell
What does the cell become if the outer shell is full?
Much more stable
What is the rough radius of an atom?
1 x 10^-10 meters