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24 terms

Atoms & the Periodic Table

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Atom
Smallest piece of matter that still retains the property of the element.
Nucleus
Protons and neutrons are found in a small positively charged center of the atom.
Protons
Particles with an electrical charge of 1+ (positively charged).
Neutrons
Neutral particles that do not have an electrical charge (no charge).
Electrons
Particles with an electrical charge of 1- (negatively charged) and are in the cloud outside the nucleus of the atom.
Quarks
Protons and neutrons are made up of these smaller particles.
Democritus
Around 400 BC he proposed the idea that atoms make up all substances.
John Dalton
In the 1800's he was able to prove atoms exist.
Niels Bohr
In 1913 he hypothesized that electrons travel in fixed orbits around the atom's nucleus.
Electron Cloud
The area around the nucleus of an atom where its electrons are most likely found.
Atomic Number
Equals the number of protons in an atom.
Mass Number
Sum of the number of protons and neutrons in the nucleus of the atom.
Isotopes
Atoms of the same element that have different numbers of neutrons.
Dmitri Mendeleev
In the 1800's discovered a pattern by arranging the atoms according to the atomic mass.
Henry G.J. Moseley
In 1913 arranged the elements according to their increasing atomic number.
Periodic Table
The elements are arranged by increasing atomic number and by changes in physical and chemical properties.
Groups/Families
Vertical Columns in the periodic table.
G.N. Lewis
Created the electron dot diagram.
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.
Erwin Shrodinger
Developed the electron cloud model of an atom.
Properties of Metals
Shiny luster, ductile, malleable, good conductor, mostly solid
Properties of Nonmetals
Brittle, poor conductor, mostly gas
Properties of Metalloids
Solid, brittle, semi-conductive, and metallic luster