Atom Vocabulary
Atom
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The smallest particle
of an element
the building blocks
of all matter
Element
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Is a substance that cannot be broken down
into simpler substances
Sodium atom
Subatomic particle
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particles smaller than the atom
parts of the atom
there are three main subatomic particles
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Protons
Neutrons
Electrons
Proton
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a subatomic particle
found in the nucleus of
the atom
has a positive electrical
charge
has a mass of 1 amu
used to help find the mass of an atom
used to help find the charge of an atom
determines the identity of an atom
Neutron
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a subatomic particle of the atom found in the
nucleus
has no electrical charge (neutral)
has a mass of 1 amu
used to help find the
mass of the atom
has no effect on the
charge of the atom
a different number of neutrons makes a
different isotope of the same element
Electron
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a subatomic particle found
outside of the nucleus in the
electron cloud
has a negative electrical charge
is 1/1600th the size of a proton or neutron
does NOT affect the mass of the atom
is used in determining the charge of an atom
Nucleus
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a region located in the
center of the atom
contains protons and
neutrons
contains the mass of the
atom
it has a positive electrical
charge
held together by strong
nuclear force
Electron cloud
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a region surrounding the
nucleus of an atom where
electrons are likely to be
found
is mainly empty space
is negatively charged
is arranged in energy levels
called shells or orbitals
Valence Electrons
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the electrons found on the outermost energy
level of an atom
most important
in determining
an element’s
chemical
properties and
reactivity
Atomic Number
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Number of protons in the nucleus of an atom
of an element
Atomic Mass or Mass Number
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The total number of protons and neutrons in
the nucleus of an atom
Mass (of an atom) = protons + neutrons
unit is amu (atomic mass unit)
Ion
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An atom that has gained or lost electrons and
has a charge
Anion
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A type of ion when an atom gains electrons
and becomes negatively charged
Cation
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A type of ion when an atom loses electrons
and becomes positively charged
Isotopes
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Atoms of the same element, but having a
different numbers of neutrons in their nucleus
Isotopes will have the same number of
protons (same element), but a different
number of neutrons
(different mass)
Atoms, Elements, Periodic
Table
Groups
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Vertical columns in the periodic table.
All elements in a group have the same
number of electrons in their outer orbital
Periods
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Horizontal rows in the periodic table.
All elements in a period have the same
number of atomic orbitals
Metals
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Elements that are good conductors of
electricity and heat.
Found left of “stairs”
Alkali Metals
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Group 1 (minus
Hydrogen)
Metals with one valence
electron
Alkaline Earth Metals
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Group 2
Metals with 2 valence electrons
Transition Metals
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Groups 3-12
Elements that have valence electrons at 2
different energy levels.
Nonmetals
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Elements that are poor conductors of
electricity and heat.
Found to the right of “stairs”
Metalloids
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Semi-metals
Physical properties of both metals and
nonmetals.
Halogens
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Group 17
Nonmetals with 7 valence electrons
Noble Gases
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Group 18; 8 Valence electrons
Except Helium (has 2 valence electrons)
Full valence shell- not very reactive
Properties of Matter
Molecule
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Particle that is made up of 2 or more atoms
of the same element.
Compound
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Substance made up of the combined atoms
of 2 or more elements.
Mixture
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Contains 2 or more types of substances and
does not form a new compound after mixing;
maintains individual properties.
Colloid
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A mixture of substances in which one of the
substances is suspended within the other as
small, non-dissolved particles.
Ex: hairspray (aerosols), foams (whipped
cream), gels, butter.
Mixing to make butter
Butter
Solution
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Homogeneous
mixture in which one
substance is
dissolved in another
substance
The ocean is a solution.
Solute
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A substance that is dissolved into another
Salt is a solute.
Solvent
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A liquid or gas that another substance
dissolves in
Water is a solvent
Physical Property
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Characteristics of a substance that can be
observed or measured without changing the
substance
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Size, shape, color, density, melting point, boiling
point, volume
Chemical Property
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Properties of matter that become evident
during a chemical reaction
Precipitate
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A solid formed by mixing two liquids
A yellow solid
precipitate forms
from the mixture of
two clear liquids:
potassium iodide
and lead nitrate.
Corrosiveness
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A substance that can cause damage to
another that is irreversible.
Flammability
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A measure of the extent to which a material
will support combustion
Oxidation
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The combination of a substance with
oxygen.
A reaction in which the atoms in an element
lose electrons
Luster
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The appearance of a mineral surface judged
by its brilliance and ability to reflect light.
Viscosity
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Measure of a liquid’s resistance to flow