1. The central core of the atom,
containing protons and usually
neutrons
NUCLEUS
PROTON
• Small positively charged particles that are
found in the nucleus of an atom
NEUTRON
• Small uncharged particles that are found in
the nucleus of an atom
ELECTRON
• Tiny, negatively charged, high-energy particles
that move around outside the nucleus of an
atom
VALENCE ELECTRONS
• The electrons that are farthest away from the
nucleus of an atom and are involved in
chemical interactions.
ELECTRON DOT DIAGRAM
A representation of the number of valence
electrons in an atom, using dots placed around
the symbol of an element
ATOMIC NUMBER
• The number of protons in the nucleus of an
atom
GROUP
• Elements in the same vertical column of the
periodic table. Also called family.
PERIOD
• Elements in the same horizontal row of the
periodic table.
HALOGEN
REACTIVE NON METAL
• An element belonging to Group 17 of the
periodic table.
ION
• An atom or group of atoms that has become
electrically charged.
IONIC BOND
• The attraction between oppositely charged
ions.
POLYATOMIC
ION
• An ion that is made of more than one atom.
CRYSTAL
• An orderly, three-dimensional pattern of ions
or atoms in a solid.
MINERAL
• A naturally occurring solid that has a crystal
structure and a definite chemical composition.