Atoms Flashcards
(22 cards)
Atom
the smallest unit of matter that still has the properties of an element
Nucleus
the central and most important part of an object, movement, or group, forming the basis for its activity and growth.
Protons
positively charged particle
Neutrons
neutral subatomic particle that, in conjunction with protons, makes up the nucleus of every atom except ordinary hydrogen.
Electrons
one of the three basic subatomic particles
Quarks
any member of a group of elementary subatomic particles
Democritus
Proposed the idea that atoms make up all substances.
John Dalton
An English scientist that was able to offer proof atoms exist.
Joseph Thomson
A physicist that thought electrons were evenly embedded throughout the atom.
Ernest Rutherford
A physicist that said atoms were concentrated in a central atomic nucleus surrounded by electrons.
Niels Bohr
Physicist that the nucleus contained positive protons and neutral neutrons.
Electron cloud
Electrons do not follow fixed orbits but tend to occur more frequently in certain areas.
Atomic number
the number of a chemical element in the periodic system and on the periodic table
Mass number
total number of protons and neutrons
Isotopes
a variation of an element that has the same number of protons but different numbers of neutrons
Average Atomic Mass
the weighted average mass of all naturally occurring isotopes of an element
Periodic table
a tabular array of the chemical elements organized by atomic number
Dmitri Mendeleev
Russian chemist most recognized for developing the periodic table of elements
Henry Moseley
an English physicist who significantly contributed to atomic theory by experimentally establishing the concept of atomic number
Groups
a column in the periodic table of the chemical elements
Electron dot diagram
a visual representation of an atom where the valence electrons are shown as dots surrounding the element symbol
Periods
