Ancient Atomic History
Democritus' name for the smallest indivisible piece of anything
What is an atomos?
The name given atoms with different number of neutrons (and different mass numbers)
What are isotopes?
The table that arranges elements in columns with properties that repeat from row to row
What is the Periodic Table?
His model was the first to account for the known properties of atoms
Who was Neils Bohr?
The center mass of the atom is known as this
What is the nucleus?
According to Empedocles, these four elements make up everything we see
What are earth, water, air, and fire?
A region of space around the nucleus where electrons are most likely to be found
What are orbitals?
The name of the rows on the periodic table
What are periods?
His model is also called the nuclear or planetary model of the atom
Who was Ernest Rutherford?
JJ Thompson knew that atoms had this charge
What is neutral?
This states that matter cannot be created or destroyed but it can change forms
What is the Law of conservation of mass?
This is the currently accepted model of atoms
What is the electron cloud model?
These two groups of the Periodic Table contain the most important elements for life
What are groups 1A through 8A?
In 1869 he developed an ingenious method of organizing elements that is still used today
Who was Dmitri Mendeleev?
Rejecting Democritus' philosophy of matter, this Greek philosopher argued that there was no limit to to how small a particle could be
Who was Aristotle?
This microscope is making it easier to "see" atoms
What is STEM?
These negatively-charged particles can never occupy the same space at the same time
What are electrons?
These gases in Group 8A used to make neon lights are odorless and colorless, rare, and unreactive
What are the Noble Gases?
He discovered the Law of Constant Composition (most of which is still accepted today)
Who was John Dalton?
Atoms are neutral in charge because they contain the same number of these
What are protons and electrons?
In addition to their mass and charge, this is used by scientists to tell protons, neutrons and electrons apart
What is location in the atom?
A very unstable state of an atom when an electron eventually jumps to a higher energy level
What is the excited state of an atom?
Electrons in the highest energy level of an atom
What are valence electrons?
He invented the first atomic theory
Who was John Dalton?
This reveals the number of protons in an atom
What is the Atomic Number?