Concept 1-3 Notes. Structure of the
Atom
Atom - answer The smallest particle of an element that has the properties of that
element
Proton - answer(p+) Positive particle in the nucleus
Neutron - answer(n0) Neutral particle in the nucleus with protons
Electron - answer(e-) Negative particle outside of the nucleus in the electron cloud
Quarks - answer smallest known particles that makes up p+ and n0
Valence Electrons - answerElectrons on the outermost energy level of an atom
Atomic Number - answerTells the number of p+ in an atom of the element. Used to
identify an element Periodic table arranged by these.
Mass Number - answerNot on the periodic table Tells the number of protons & neutrons
in the nucleus of an atom ( where most of its mass is located)
Isotopes - answerAtoms of the same element with different numbers of neutrons
Average Atomic Mass - answerWeighted average of all the isotopes of an element;
closest to the most common isotope of the element
Groups/Families - answerThe vertical columns in the periodic table; contain elements
with similar chemical properties and the same number of valence electrons ( skipping 3-
12)
Periods - answerHorizontal rows on the periodic table; every element in that row has the
same number of energy levels (shells)
Democritus (400 BC) - answerFirst to name the atom
John Dalton (1803) - answerHe believed that an atom is a solid sphere that can get any
smaller. Elements are made of atoms that all have the same mass and compounds are
atoms of different element combined.
Dmitri Mendeleev (1869) - answerDeveloped the first periodic table of elements,
organized by atomic mass
Atom
Atom - answer The smallest particle of an element that has the properties of that
element
Proton - answer(p+) Positive particle in the nucleus
Neutron - answer(n0) Neutral particle in the nucleus with protons
Electron - answer(e-) Negative particle outside of the nucleus in the electron cloud
Quarks - answer smallest known particles that makes up p+ and n0
Valence Electrons - answerElectrons on the outermost energy level of an atom
Atomic Number - answerTells the number of p+ in an atom of the element. Used to
identify an element Periodic table arranged by these.
Mass Number - answerNot on the periodic table Tells the number of protons & neutrons
in the nucleus of an atom ( where most of its mass is located)
Isotopes - answerAtoms of the same element with different numbers of neutrons
Average Atomic Mass - answerWeighted average of all the isotopes of an element;
closest to the most common isotope of the element
Groups/Families - answerThe vertical columns in the periodic table; contain elements
with similar chemical properties and the same number of valence electrons ( skipping 3-
12)
Periods - answerHorizontal rows on the periodic table; every element in that row has the
same number of energy levels (shells)
Democritus (400 BC) - answerFirst to name the atom
John Dalton (1803) - answerHe believed that an atom is a solid sphere that can get any
smaller. Elements are made of atoms that all have the same mass and compounds are
atoms of different element combined.
Dmitri Mendeleev (1869) - answerDeveloped the first periodic table of elements,
organized by atomic mass
