Atoms and the Periodic Table Flashcards
Smallest piece of matter that still retains there property of the element.
Atom
The center of the atom and where protons and neutrons are found. Also is surrounded by a cloud containing electrons.
Nucleus
Particles with electrical charge of 1+.
Protons
Neutral particles that do not have an electrical charge.
Neutrons
Particles with an electrical charge of 1-.
Electrons
Protons and neutrons that are made up of smaller particles.
Quarks
Ancient Greek Philosopher that Proposed that matter was uniform throughout and was not composed of smaller particles.
Democritus
An English scientist, that was able to offer proof that atoms exist.
John Dalton
English physicist that inferred from his experiments that atoms contained small, negatively charged particles. He thought these “electrons” were evenly embedded throughout a positively charged sphere.
Joseph Thomson
British physicist that Proposed that almost all the mass of an atom- and all its positive charges- were concentrated in a central atomic nucleus surrounded by electrons.
Ernest Rutherford
Danish physicist that hypothesized that electrons traveled in fixed orbits around the atom’s nucleus.
Niels Bohr
The area around the nucleus of an atom where its electrons are most likely found.
Electron cloud
The number of protons in an atom is equal to a number.
Atomic number
The sum of the number of protons and the number of neutrons in the nucleus of an atom.
Mass number
Atoms of the same element that have different number of neutrons.
Isotopes
The weighted average mass of the mixture of its isotopes.
Average atomic mass
The elements are arranged by increasing atomic number and by changes in physical and chemical properties.
Periodic table
Discovered that the elements had a periodic pattern in their chemical properties.
Dmitri Mendeleev
A young English scientist that led the arrangement of elements based on their increasing atomic numbers instead of an arrangement based on atomic masses.
Henry Moseley
The vertical columns in the Periodic table.
Groups
Uses the symbol of the element and dots to represent the electrons in the outer energy level.
Electron dot diagram
The horizontal rows of element on the periodic table
Periods
