AtomBasic Component
of Matter
Electrons Negatively charged
particles
NucleusTiny, massive core containing protons
and neutrons
ProtonsPositively charged particles
in an atom’s nucleus
Made of 3 quarks
Energy Level Specific amount of energy
an electron has
Neutron Particles in the nucleus of
an atom that has no electric charge
Atomic NumberNumber of protons in
nucleus of an atom
Isotopes Atoms of the same element but have a different amount of
neutrons
Mass NumberThe sum of the protons
and neutrons in the nucleus. Note: a whole number because it refers to specific atom.
Atomic MassAverage mass of all
isotopes
Periodic Table Arrangement of elements
showing repeating pattern of elements
Periods Horizontal rows in the periodic table
Groups Vertical columns of the periodic table
Chemical Symbol Symbol of an element
using letters
Metals
An element that is a conductor of heat
MalleableMaterial that can be
hammered, rolled into flat sheets, or shaped
DuctileMaterial that can be pulled
out into a long wire
Thermal Conductivity Ability of an object to
transfer heat
Electrical Conductivity
Ability of an object to transfer electricity
Reactivity The speed which a substance reacts with other substances
CorrosionGradual wearing wearing of a
metal because of chemical reaction
Alkali Metals Metals in group one of the
periodic table
Alkaline Earth Metals
Group two of the periodic table
Transition Metals Elements in group three to group
twelve on the periodic table
Particle AcceleratorsPowerful machines that move
atomic nuclei really fast
Nonmetal Elements that lack most
properties of metal
Diatomic Molecule
Molecule that consists of two atoms
HalogensGroup 17 of the periodic
table
Inert Gases
Group 18 of the periodic table
Semimetals
Elements that have some metal and have some properties that are
nonmetal
Semiconductors Substances that can conduct an electric current under some circumstances and
cannot in some circumstances
Radioactive Decay Atomic nuclei of isotopes
release fast-moving particles and energy
Radioactivity Property that is able
to emit radiation
Alpha Particle
Consists of two neutrons and two protons and is positively
charged
Beta Particle Fast moving electron that is given off by a nucleus during radioactive
decay
Gamma Radiation
High energy waves
TracersRadioactive isotopes that can be
followed using a detector
MoleculeTwo or more atoms
joined in chem. bond
CompoundA pure substance made of
two or more elements chemically combined