Atomic Theory
This Greek philosopher first suggested that matter is made of tiny particles called atoms.
Who is Democritus?
This subatomic particle has a positive charge.
What is a Proton?
These are the horizontal rows on the periodic table.
What are periods?
Elements that are shiny and conduct electricity well.
What are metals?
These are the electrons located in the outermost energy level.
What are valence electrons?
This philosopher disagreed with Democritus and believed matter was made up of four elements.
Who is Aristotle?
What is a neutron?
Elements that are poor conductors are often dull.
What are nonmetals?
The first energy level can hold this many electrons.
What is 2?
Who is John Dalton?
These negatively charged particles move around the nucleus.
Elements in the same group have the same number of these.
What are valence electrons?
What are metalloids?
The second level can hold up to this many electrons?
What is 8?
This scientist discovered the electron using cathode ray experiments.
Who is J.J. Thomson?
The center of an atom, where the protons and the neutrons are found.
This scientist created the first periodic table and left blank spaces for unknown elements.
Who is Dmitri Mendeleev?
What are alkali metals?
Bohr suggested electrons travel in orbits around the nucleus.
What are energy levels (or shells)?
This scientist performed the gold foil experiment and discovered the nucleus.
The number of protons in an atom determines the element.
What is the atomic number?
This scientist arranged the periodic table by increasing atomic number.
Who is Henry Moseley?
These elements are very stable and rarely react with other elements.
What are noble gases?
This is the rule where an element wants 8 valence electrons in the outermost shell. (hint: nonmetals tend to gain electrons)
What is the rule of Octect?