Atoms and ions Flashcards
Atom
The basic particle from which all elements are made is the smaller particle of an element that has properties of that element.
Electron
A tiny, negatively charged particle that moves around the outside of the nucleus of an atom
Nucleus
The central core of an atom, which contains protons and neutrons
Proton
A small, positively charged particle that is found in the nucleus of and atom
Neutron
a small particle in the nucleus, with no electrical charge
Atomic number
the number of protons in the nucleus of an atom
Isotope
An atom with the same number of protons and a different number of neutrons form other atoms of the same element
Mass number
The sum of protons and neutrons in the nucleus of an atom
Democritus
in 400 B.C.E. he theorized that all material bodies are made up of extremely small “atomos”
John Dalton
In 1803 he said that all matter was comprised of invisible and indestructible atoms with distinct masses and properties.
J.J. Thomson
In 1897, he discovered negatively charged particles called electrons, he stated that electrons must be stuck all throughout a positively charged area
Ernest Rutherford
He discovered that an atom is mostly empty space, and nearly all of its mass is concentrated in the central nucleus.
James Chadwick
He discover uncharged particles and called them neutrons.
Nelis Bohr
He discovered the electrons are arranged in energy levels.
Atomic mass
The average mass of all the isotopes of an element
Periodic table
An arrangement of elements showing the repeating pattern of their properties
