Atom Flashcards
Atom
The smallest piece of matter.
Nucleus
The charged center of an atom.
Protons
Particles with electrical charge of 1+
Neutrons
Neutral particles that don’t have an electrical charge.
Electrons
Particles with an electric charge of 1-
Quarks
Smaller particles that make of Protons and Neutrons.
Democritus
He proposed the idea that atoms make up all substances.
John Dalton
He created the atom model.
Joseph Thomson
Inferred that atoms had negatively charged particles called electrons.
Ernest Rutherford
Proposed that all the mass of an atom is concentrated in a central atomic nucleus.
Niels Bohr
Hypothesized that electrons traveled in fixed orbits around the atom’s nucleus.
Electron Cloud
The area around the nucleus of an atom where the electrons are most likely found.
Atomic NUmber
The number of Protons in an atom is equal to a number.
Mass Number
The sum of the number or protons and neutrons in the nucleus of the atom.
Isotopes
Atoms of the same element that have different numbers of neutrons.
Average Atomic Mass
The weighed-average mass of the mixture of its isotopes.
Periodic Tables
Elements are arranged by increasing atomic number and by changes in the physical and chemical properties.
Dmitri Mendeleev
Searched for a way to organize the elements.
Henry Moseley
Led to the arrangement of the elements based on the increasing atomic number.
Groups
Otherwise known as families, are numbered 1 through 18.
Electron Dot Diagram
Uses the symbol of the element and dots to represent the electrons in the outer energy level.
Periods
The horizontal rows of elements on the periodic table.
