Transcript Atoms and Periodic Table

Atoms
The smallest particle of an element.
Valence Electrons
• Electrons
located in the
outermost
energy level
of an atom
Proton
• located inside
nucleus
• positively charged.
Neutron
• located inside
the nucleus
• no charge.
Electron
• located outside
the nucleus in
the electron
cloud
• negatively
charged.
Atomic Number
• Number of protons in
an element
• Also the number of
electrons in a stable
element.
Mass Number
• Number of atomic
particles in the
nucleus of an atom
• Protons + neutrons =
mass number
• Also referred to as
atomic mass.
Energy Levels / Shells
• The space an
electron occupies in
the electron cloud
• Determined by the
amount of energy the
electron contains
• Less energy = lower
level
• More energy= higher
level.
Element
A substance that cannot be broken down
into any other substances by chemical or
physical means.
Groups
Elements in the same vertical (up and down)
column of the periodic table; also called a
family.
Periods
A horizontal row (side-to-side) of elements in
the periodic table.
Alkali Metals
Elements with only one
electron in the
outermost energy
level of their atoms;
located in Group 1 on
the Periodic Table;
not stable and tend
to lose their one
electron easily.
Alkaline Earth Metals
• Elements in
group/family 2.
• Form positive
ions
• 2 valence
electrons
Transition Metal
• any element in any of
the series of elements
with atomic
numbers 21–29, 39–
47, 57–79, and 89–
107, that in a given
inner orbital has less
than a full quota of
electrons
Halogens
Elements that have seven valence electrons
in their atoms; need one additional
electron to have a filled outer energy level;
tend to gain one electron from other
elements; not stable.
Noble Gas
The elements located I the far right column
of the Group 18; their outermost energy
level is holding the maximum number of
electrons possible; stable.
Metalloid/Semiconductor
• an element that has
both metallic and
nonmetallic
properties, as arsenic,
silicon, or boron.
Lanthanide Series
• Fifteen elements that
start with lanthanum
(La) at atomic number
57 and finishing up
with lutetium (Lu) at
number 71.
Actinide Series
• Fifteen elements that
start with actinium
(Ac) at atomic number
89 and finishing up
with lawrencium (Lr)
at number 103.
• They are all
radioactive and some
are not found in
nature.
Metals
An element that easily
gives up its valence
electron in a chemical
reaction and that be
classified based on
physical properties
such as hardness,
shininess, ease of
malleability, and
ductility.
Nonmetal
An element
that lacks
most of the
properties of
metals.
Ions
An atom that has an electrical charge
because it no longer has an equal number
of protons and electrons.
Isotope
• any of two or more forms
of a chemical element,
having the same number
of protons in the nucleus,
or the same atomic
number, but having
different numbers of
neutrons in the nucleus,
or different atomic
weights.