Theories and Models
Chapter 4 Key Terms
Chapter 5 Key Terms
Periodic Table Groups
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100
That the universe was made up of indivisible units.
What is Democritus' Theory?
100
A subatomic particle that has a negative charge.
What is an electron?
100
The law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements.
What is the periodic law?
100
Group 1: Alkali Metals
What is in Group 1?
100
Rutherford proposed that most of the atom was concentrated at the atoms center.
What is Rutherford's Model?
200
All atoms of a given element were exactly alike, and atoms of different elements could join to form compounds.
What is Dalton's Theory?
200
An atom's central region, which is made up of protons and neutrons.
What is the nucleus?
200
A horizontal row of elements in the periodic table
What is a period on the periodic table?
200
Group 2: alkaline-earth metals
What is in Group 2?
200
An element that conducts heat and electricity poorly.
What is a nonmetal?
300
Thomson's cathode-ray tube experiment suggested that cathode rays were made of negatively charged particles that came from inside atoms.
What is Thomson's Model?
300
A subatomic particle that has a positive charge and that is located in the nucleus of an atom.
What is a proton?
300
A vertical column of elements in the periodic table. They share chemical properties
What is a group on the periodic table?
300
Group 2: alkaline-earth metals
What is in Groups 3-12?
300
One of the metals that can use the inner shell before using the outer shell to bond.
What is a transition metal?
400
Electrons have a set path.
What is Bohr's Atomic Theory?
400
A subatomic particle that has no charge and that is located in the nucleus of an atom.
What is a neutron?
400
An element that is shiny and that conducts heat and electricity
What is a metal?
400
An atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons.
What is an isotope?
500
Electrons can be found only in certain energy levels. Furthermore, the location of electrons cannot be predicted precisely.
What is the Modern Atomic Theory?
500
The number of protons in the nucleus of an atom.
What is the atomic number?
500
An element or compound that conducts electric current better than an insulator does but not as well as a conductor does.
What is a semiconductor?
500
A unit of mass that describes the mass of an atom or molecule. It is exactly 1/12 the mass of a carbon atom with a mass number of 12 (symbol, u)
What is the unified atomic mass unit?
M
e
n
u