1periodic table review

Atomic Structure and the Periodic
All Matter is Made of Atoms
 Hydrogen is the most
common atom of our
 Types of atoms in Earth’s
Iron 5%, Aluminum 8%,
Silicon 28%, Oxygen 47%,
Other 12%
 Types of atoms in Humans
Nitrogen 3%, Hydrogen 10%,
Oxygen 61%, Other 26 %
Names and Symbols of Elements
 Each element has its own symbol
 Some elements use the first letter of the name:
hydrogen (H), Sulfur (S),Carbon (C)
 Other elements use the first letter of the name
plus another letter: aluminum (Al), Platinum (Pt),
Zinc (Zn)
 The first letter is always capitalized and the
following letters are lower case.
Early Greek Philosophers
determined that atoms are the
building blocks of matter.
John Dalton (1766–1844)
John Dalton’s theory of the
atom started out as a solid
sphere with no charges
Proposed the atomic theory
by investigating atomic
weights of atoms
J.J. Thomson determines that an atom
is made up of negative electrons
embedded in a sea of positive charges .
- +
Ernest Rutherford did some
experiments with thin metal foils and
found that the positive charge is
located within a central nucleus
Neils Bohr worked under Rutherford but
found problems with his theory. He
ultimately determined that Electrons are in
circular orbits with increasing energy
The modern atomic model shows that
electrons occupy regions of space
whose shape is described by complex
mathematical equations. (James
History of Atomic Theory
 John Dalton’s theory of the atom started out as a solid
sphere with no charges.
 Then J.J. Thomson figured out there were positive and
negative charges in an atom.
 Rutherford determined that the positive charges
(protons) were located in the center of the atom and the
negative charges (electrons) were scattered around the
 Bohr’s theory said that the protons are in the middle and
the electrons travel in specific energy levels and orbits
around the nucleus
 Modern model- protons and neutrons in nucleus,
electrons on energy levels
IP 15: Electron Configuration &
Periodic Table Organization p.
 An atom is made up of protons (+),
neutrons (no charge), and electrons(-).
 The protons and neutrons are found in the nucleus
 There has to be an equal number of protons and
electrons because atoms have no net charge!
 Atomic mass is the number of protons and
 Atomic number is the number of protons (which is
the same as the number of electrons)
Atom: the smallest particle of an element that has the
chemical properties of the element
Nucleus: found in the center of the atom and contains the
protons and neutrons
Proton: a positively charged particle found in the nucleus
of an atom
Neutrons: an uncharged particle found in the nucleus of an
Electron: negatively charged particles that move around
outside the nucleus of the atom
Isotopes: atoms of the same element that have a different
number of neutrons. Chlorine atoms have 17 protons, but some
atoms of chlorine have 18 or 20 neutrons these atoms are the
isotopes of chlorine
Atoms form Ions
Ions: formed when an atom loses or gains one
or more electrons(- or + charge)
Cation: formed when an atom loses an
electron (+ charge)
Anion: formed when an atom gains an
electron (- charge), larger radius.
Elements are organized by similarity
Modern Periodic Table
organized by the atomic
# of the elements
Dmitri Mendeleev began
organizing elements by
their physical and
chemical properties
How is the Periodic Table organized?
Mendeleev produced
the first periodic table
organized by the
atomic # of the
Named the periodic
table because a
periodic, or repeating
pattern of properties of
the elements
How is the Periodic Table organized?
 Period: each row of the periodic
table is called a period. If you
read from left to right one
proton and one electron are
added from one element to the
 Group/Family: name for each
column of the table. Read top to
-share similar properties.
-divided into Representative
elements= Groups 1-8 &
Trans. Metals
Aufbau Process: lowest energy
orbitals first.
Valence Electrons
Valence Electrons
How many
How many
Valence Electrons (Cont’d)
 Determined by the elements’ Group
Lewis Dot Structure
All elements in the 1st group have
only 1 valence electron. All elements
in the first group have a Lewis Dot
Structure like this:
Atomic Size on the Periodic Table
Left to right atomic size decreases
Top to bottom atomic size increases
More Properties of Periodic Table
Periodic Table has distinct regions
Reactive: indicates how likely an
element is to undergo a chemical
Most elements are somewhat reactive
and combine with other materials
The most reactive are in groups
(up/down) 1 and 17
The least reactive are in group
(up/down) 18
Elements combine by the outside
 All of the electrons in the combining elements do not interact with
each other to form compounds….
 Valence Electrons: Only the electrons in the element’s outside
energy level interact with each other.
 The most stable configuration has 8 electrons in the outer
energy level.
 Elements in group 1 have 1 electron in outside energy level and
elements in group 17 have 7 electrons in outside energy level so
they react with each other easily to form compounds and fulfill the 8
electron stable configuration.
Most elements are
Metals are elements
that conduct
electricity and heat,
have shiny
appearance, and can
be shaped by
(malleability), bending,
or being drawn into a
thin wire (ductility)
Metals (Cont’d)
Reactive metals:
Group 1 (up/down)
most reactive
Transition Metals:
Group 3-12
generally less
reactive than most
Rare Earth Elements
 Top row of the two rows of metals that are outside of the main
periodic table
 Also known as Lanthanides because they follow the element
lanthanum (La) on the table
 Scientists once thought these metals were available only in tiny
amounts on the Earth
• bottom row of the two
rows of metals that are
outside of the main
periodic table
• The Actinide series is
all radioactive and
some are not found in
Nonmetals: the elements on the right side of
the periodic table
Many are gases at room temperature, dull
surfaces on the solid nonmetals, cannot be
shaped by ductility or malleability
Elements in group 17
7 valence electrons
Greek “forming salts
Very reactive nonmetals
Easily form compounds
w/ metals. These
compounds are known
as salts.
Noble Gases
Group 18 on the
periodic table
8 valence e(electrons)
Noble or inert
because they
almost never react
with other
Have properties
of both metals &
Located on
either side of the
zigzag line
metals and
Most common is
Summary: 3 N/H
-Valence e-Lewis Dot Structures
-Group characteristics
Poor Metals
 Radioactivity: the process by
which the nucleus of an atom
releases energy and particles
 Marie Curie was the first person to
isolate two radioactive elements
(polonium and radium)
 An isotope is radioactive if the
nucleus has too many or too few
 Radioactive atoms
produce energy and
particles from their nuclei
Radioactive Decay
 The identity of these
atoms changes because
the # of protons changes.
(radioactive decay)
 Occurs at a steady rate
characteristic to each
 The amount of time for
one-half of the atoms to
decay is called the halflife of the isotope
Radioactive Decay
 Parent decays into daughter isotope.
 Combination of both is 100%
 Parent starts at 100% and decays to 50%
 100% 1 half-life to 50% (daughter 50%)
 50% 2 half-lives to 25% (daughter 75%)
 25% 3 half-lives to 12.5% (daughter 87.5%)
 12.5% 4 half-lives to 6.25% (daughter 93.75%)
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