The Periodic Table
The Periodic Table
Intro to the Periodic Table
Intro to the Periodic Table
Intro to the Periodic Table
Dobereiner:
Developed ‘triads’ that
groups elements based on
common characteristics.
No arrangement between
triads, however.
Dmitri Mendeleev
Mendeleev:
Developed a version of the periodic table of elements that reflected patterns and properties.
Biggest contribution: leaving blank spaces predicting elements (and their properties) that had yet to be discovered!
Intro to the Periodic Table
In 1913 Henry Mosely (along with Rutherford)discovered the idea of positive charge within thenucleus. Discovered each element had a certain
amount of positive charge in the center. Called these whole number positive charges
atomic number. Determined the atomic number of all known
elements at that time.
B. Moseley
Mosely: Arranged the periodic table in order of
increasing atomic number.
- This is the way the table is
currently arranged.
- Remember # of protons =
atomic #
Intro to the Periodic Table
Periodic Law: The properties of elements are
periodic – that is a repeating pattern of chemical
and physical properties. (they repeat in a
systematic way)
Key Idea
For example, which elements are similar to sodium?
Elements in the same group have similar properties.
This is because they have the same # of valence
electrons!
Intro to the Periodic Table
Valence Electrons:
Outermost electrons in an atom (responsible for
properties of an element).
Intro to the Periodic Table
Example: State the valence electrons for the
Following elements.# of valence electrons
Li Mg Al O Cl Ne
Lewis Dot Diagram
Periodic TrendsValence electrons and group properties:Each element in a group has similar properties, due to all members
having the same number of valence electrons.
Metals: Nonmetals:
Form (+) ions Form (-) ions
Lose electrons Gain electrons
Group 1 Group 2 Groups 3-12 Group 13 Group 14 Group 15 Group 16 Group 17 Group 18
1 Valence Electron
2 Valence Electrons
Varies 3 Valence Electrons
4 Valence Electrons
5 Valence Electrons
6 Valence Electrons
7 Valence Electrons
8 Valence Electrons
+1+2 Varies +3 +/- 4 -3 -2 -1 No Ions
Ever wonder what people who like science and
music do in their spare time?
https://www.youtube.com/watch?v=VgVQKCcfwnU
Groups of the Periodic Table
http://periodictable.com/index.html
Groups of the Periodic Table
Hydrogen:
Has 1 valence electron, so it
is placed with
group1 but it is NOT a
metal. One of the more
common elements in the
universe.
Groups of the Periodic Table
Alkali Metals:
Very reactive, explosive metals (often grey, soft).
1 valence electron and forms +1 ions.
Alkali Metal Reactivity
Reactivity with air & water:
http://www.youtube.com/watch?v=uixxJtJPVXk&safety_mode=true&persist_safety_mode=1&safe=active
Brainiac’s play with alkali metals:
http://www.youtube.com/watch?v=m55kgyApYrY&safety_mode=true&persist_safety_mode=1&safe=active
Groups on the Periodic Table
Alkaline Earth Metals:
Reactive metals, tend to be found in compounds
in nature. 2 valence electrons and forms +2 ions.
Groups on the Periodic Table
Transition Metals:
Stable metals. Can form
more than one (+) ion
b/c they can change the #
of electrons lost. They
form colorful (+) ions
when in a solution.
Groups on the Periodic Table
Lanthanide Series:
4f block of elements
Actinide Series: 5f block of
elements. Almost all
are man-made, all are
radioactive.
Groups of the Periodic Table
Halogens:
Reactive nonmetals.
Group contains all 3 states
of matter (s,l,g). Mainly
form -1 ions b/c they
only need 1 valence
electron to achieve octet.
Reactivity of Halogens:
http://www.youtube.com/watch?v=u2ogMUDBaf4
Groups of the Periodic Table
Noble Gases:
Stable valence electron configuration, which
means they are nonreactive – they have a full
octet (remember that # is 2 for He, but 8 for the
rest of the group.)
Group 13
+3 Ion
Group 14
+/- 4 Ion
Group 15
-3 Ion
Group 16
-2 Ion
Groups of the Periodic Table
Metals SemimetalsMetalloids
Nonmetals
Malleable, ductileShiny (luster)Lose electrons = (+) ionsGood conductorsOnly liquid: Hg (rest are solid)
7 total (on step line)B, Si, Ge, As, Sb, Te, At
Properties are in between metals and nonmetals
BrittleNonconductorsGases, liquid (Br), and solidsGain electrons = (-) ions
The Octet Rule:
Atoms will lose, gain or
share electrons to achieve
stability – a full octet of 8
valence electrons.
Metals accomplish this by
losing electrons.
Nonmetals gain electrons
to fill the valence shell.
Exception: 1st PEL only
holds 2 electrons.
As you move across a period:
- # of PEL’s stays the same
- # of protons increases
- # of e- in the valence shell increases
which increases attraction.
Coulombic attraction increases b/c
atomic radius decreases.
As you move across a period the # of
protons increases & the # of e- in the
valence shell increases, which
increases attraction.
Coulo
mbic
att
ract
ion d
ecre
ases
b/c
ato
mic
rad
ius
incr
ease
s. I
ncr
ease
in #
of
PE
L’s
cau
ses
e-to
be
fart
her
fro
m
the
nucl
eus
dec
reas
ing a
ttra
ctio
n.
Coulo
mbic attractio
n in
creases b/c
atom
ic radiu
s decreases.
As y
ou m
ove acro
ss a perio
d th
e # o
f
pro
tons in
creases & th
e # o
f e-in
the
valen
ce shell in
creases, which
increases attractio
n.
Coulombic attraction decreases b/c
atomic radius increases. Increase in #
of PEL’s causes e- to be farther from
the nucleus decreasing attraction.
Periodic TrendsPeriodic Trends:
Predictable patterns across the periodic table
(atomic radius, metallic character, ionization
energy, electronegativity) and down the groups.
Atomic Radius:
Across a period:
Get Smaller
Down a group:
Get Larger
Metallic Character:
How much an atom acts
metallic – i.e. how easily it
loses electrons.
Across a period:
Decreases ( you are heading
towards the nonmetals)
Down a group:
Increases (easier to lose an
electron if the atom is
bigger).
* Most metallic elements are in the lower left corner.
+ ion:
Loss of an electron
reduces the electron cloud
size. Radius decreases.
- ion:
Gain of an electron
increases electron cloud
size. Radius increase.
Ionization Energy:
Energy to remove
outermost electron
Across a period:
Increase
Down a group:
Decrease
Electronegativity:
Ability to attract an electron
(“affinity for electrons”)
Across a period:
Increase
Down a group:
Decrease