What do the numbers mean?
11
Na
22.990
sodium
This is the atomic number. It
is the number of protons in a
single atom of this element. It
is also # of electrons.
The symbol for this element.
This is the average atomic mass,
it is the number of protons +
neutrons, or the mass of the
nucleus of an atom.
This is the name of the element.
Periods
 Horizontal
rows on the table
 Correspond to the outermost energy
level of electrons being filled.
Groups





Vertical columns on the table
All groups have number designations
Are also called families
Same/similar physical and chemical
properties due to VALENCE ELECTRONS!
Some groups have special family names
based upon characteristics of elements in
that group
Regions of the Periodic
Table
 Metals
 Nonmetals
 Metalloids (semi-conductors)
 Transition metals
 Inner-transition metals
 Lanthanide Series
 Actinide Series
 Transuranium elements
Metals
Properties of element types:
1) Metals- high luster, good conductors,
ductile, malleable, most are solid at room
temp (except Hg is liquid)
2)Nonmetals- low luster, poor conductors,
very brittle, various states of matter at
room temperature (ex: S is solid, O is gas,
Br is liquid)
3) Semi-Conductors - sit on stair-step line
metals and non-metals; have properties
between metals and non-metals
Nonmetals
Semi Conductors
Transition Metals
Inner-Transition Metals
Regions of the Periodic
Table Continued



Radioactive elements ( atomic # > 83)
Most active metals (Fr)
Most active nonmetals (F)
 (A) Periods of the periodic table, and (B)
groups of the periodic table.
Family Names
Alkali Metals (Group 1)
 Alkaline Earth Metals (Group 2)
 Halogens (Group 7)
 Noble gases (Group 8)

Alkali Metals (Group 1)
 Form metal hydroxides (strong bases)
when reacting in water
 2 Na + 2 HOH
 2 NaOH + H2
 Are generally very reactive compared to
other groups of metals
 Have one valence electron
 Form cations with a +1 charge
 Brainiac: Alkali Metals
Alkali metals
Alkaline Earth Metals
(Group 2)
Form metal hydroxides (strong bases)
when reacting in water
Ca + 2 HOH

Ca(OH)2
+ H2
Are not as reactive as alkali metals
but are generally more reactive than
transition elements
Have two valence electrons
Form cations with a +2 charge
Alkaline earth metals
Halogens (Group 7)
Form a multitude of salts
 Are generally very reactive when
compared to other nonmetals
 Have seven valence electrons
 Form anions with a -1 charge

Halogens
Noble Gases (Group 18)
Are generally unreactive (inert)
 Have eight valence electrons
 Some compounds with xenon and
krypton have been synthesized

Nobel Gases – Group 18
 Atomic
Radius
 Ionization Energy
 Electron Affinity
 Ionic Radius
 Electronegativity
 Metallic Character
 Nonmetallic Character
Atomic Radii Trends on the
Periodic Table
For the main group
elements:
 atomic radii
increase going
down a group
 decrease going
across a period.
Going down a group radii increases
because:
 Energy
level is added for each
successive period
Ionization Energy
Is defined as the energy required to
remove an electron from an atom in
the gas phase.
Each atom can have a series of
ionization energies, since more than
one electron can always be removed
(except H).
First Ionization Energy Trends on the
Periodic Table
First ionization energies generally increase
across a period and decrease down a group.
Generally, the larger the atom the easier it is
to remove an electron and the less ionization
energy required.
 WHY? The outermost electrons are found in
higher energy levels as one goes down the
group. Since the electrons are farther
from the nucleus's pull the electrons are
more easily removed.
Ability to lose an electron by type
Low ionization energies are typical
of active metals.
High ionization energies are typical
of active nonmetals.
Very high ionization energies are
found with the Noble Gases
Ionization Energy
(kJ/mol)
Plot of First Ionization Energies
For Periods 1-4
Ionic Radii
 Cations
(+) have lost one or more
electrons and are smaller than
the atoms from which they were
derived.
 Anions (-) have gained one or
more electrons and are larger
than the atoms from which they
were derived.
Anions (negative ions) are larger
than their respective atoms.
WHY? Electron-electron repulsion
forces spread them further apart.
Electrons outnumber protons; the
protons cannot pull the extra
electrons as tightly toward the
nucleus.
Cations (positive ions) are smaller
than their respective atoms.
WHY?
Protons outnumber electrons; the protons
can pull the fewer electrons toward the
nucleus more tightly. If the electron that
is lost is the only valence electron so that
the electron configuration of the cation is
like that of a noble gas, then an entire
energy level is lost. In this case, the
radius of the cation is much smaller than
its respective atom.
Metallic Character
 Is
•
•
•
•
associated with:
Larger atomic radii
Lower ionization energies
Lower electron affinities
Lower electronegativities
 The
most active metals (ones with the
most metallic character) are located in
the lower left corner of the table.
Nonmetallic Character
 Is
•
•
•
•
associated with:
Smaller atomic radii
Higher ionization energies
Higher electron affinities
Higher electronegativities
 The
most active nonmetals are found
in the upper right hand corner of the
periodic table (excluding the Noble
gases).
What About the Noble Gases?
do not behave as metals or nonmetals.
 very high ionization energies and positive
electron affinity values.
 Noble gases usually are not assigned
electronegativities due to their tendency
to not form chemical bonds.
 Have full valence electron shells so they
do not tend to form compounds at all.

Chemical Reactivity




Metals increase
in reactivity left
and down.
Nonmetals
become more
reactive up and
to the right.
Most reactive
metal is? Fr
Most reactive
nonmetal is?
F