Name:

Atomic Theory Vocabulary Fill-in

Atom
Tiniest particle of an element that has all the _____________________ of the element. Atoms are composed of protons, neutrons and electrons.
Nucleus
_____________________ part of an atom made up of the protons and neutrons.
Atomic mass units (AMU)
Unit to describe the _____________________ of atoms, molecules and subatomic particles. The new name for this unit is _____________________ (D).
Protons (p+)
_____________________ -charged _____________________ particle found in the nucleus. Its mass is ________ AMU.
Neutrons (no)
_____________________ subatomic particle found in the nucleus. Its mass is one __________.
Electrons (e-)
Negatively-charged _____________________ particle found in the electron cloud. Its mass is _____________________ .
Electron cloud
The space around the nucleus of the atom through which the electrons move.
Electron shell/orbital
Energy level of an electron that we model as an orbit the e- will travel around as it circles the nucleus. If the orbit is farther from the nucleus, we say the e- has more energy.
Atomic number
Number of _____________________ in an atom.
Mass number
Mass of an atom in atom mass units (AMU). It is the _____________________ of the number of protons and neutrons.
Isotopes
Atoms of the same element having different _____________________ of _____________________ . Isotopes have the same _____________________ properties.
Atomic mass
_____________________ of the masses of naturally occurring _____________________ of an element, weighted by abundance.