He thought all matter was composed of small particles he called atomos, meaning "uncuttable" in greek.
Who is Democritus?
100
This positively charge subatomic particle is found in the nucleus of an atom.
What is the proton?
100
The number of protons an element has is this number on the periodic table.
What is the atomic number?
100
This property of metal is also called "shine".
What is luster?
100
Solid nonmetals are not shiny and hard like metals, instead they are _____________ and _____________.
What is dull and brittle?
200
He was the first scientist to propose an atomic theory. He thought the atom looked like a microscopic billiard ball.
Who is John Dalton?
200
This subatomic particle has no charge and exists in the nucleus of an atom.
What is the neutron?
200
Mendeleev organized elements on the periodic table according to this number.
What is atomic mass?
200
The destruction of metal when exposed to oxygen is called this.
What is corrosion?
200
The most reactive nonmetal group on the periodic table is this group.
What is the halogens?
300
He hypothesized that atoms were like positive "pudding" stuffed full with negative "plums".
Who is J.J. Thomson?
300
This subatomic particle has virtually no mass and exists around the nucleus in "clouds."
What is the electron?
300
The number of protons plus the number of neutrons in an element will provide this number.
What is the atomic mass?
300
This property of metals allow it to be pulled into wires.
What is ductility?
300
This group of nonmetals has full outer shells and therefore does not react with other elements.
What is the noble gases?
400
In 1911, this scientist discovered that atoms are mostly empty space with a small, positively charged center.
Who is Ernest Rutherford?
400
Two atoms that have the same number of protons but different numbers of neutrons are called this.
What are isotopes?
400
Vertical columns on the periodic table are called either ___________ or ____________. Alkali metals is an example.
What are groups or families?
400
This group of metals on the periodic table are the most reactive.
What are the alkali metals?
400
This is the state of matter that most nonmetals are in at room temperature.
What is gas?
500
In 1913, this scientist hypothesized that the electrons existed in energy levels and orbited the nucleus like planets around the sun.
Who is Niels Bohr?
500
These two subatomic particles must be equal in number for an atom to have no charge.
What are electrons and protons?
500
The zigzag line found in the periodic table separates _______________ from _____________ ; almost all elements touching the zigzag are called ______________
What are metals from nonmetals; metalloids?
500
These two things travel through metal, making it a good conductor.
What are electricity and heat?
500
This is the one element on the periodic table that does not fit well into a group and therefore stands alone.