Download Periodic Table Workshop

I. CHEMICAL PERIODICITY
"the variation in
properties of elements
based on their positions
in the periodic table”
Dmitri Mendeleev
• a 19th cent. Russian chemist,
published (1862) an
arrangement of elements
based on chem. properties of
the elements, so that
elements with similar
properties fell in the same
column (62 known in his time)
• Brilliant b/c: he left spaces in
columns for yet-undiscovered
elements
Lothar Meyer
• a 19th century German
chemist, published an
arrangement of elements
based on physical
properties of elements
• the two tables were
surprisingly similar, and
emphasized regular
periodic repetition of
properties of elements
with increasing a.w.
Periodic Law
• a revision of Mendeleev's/Meyer's
groupings, states that "the
properties of the elements are
periodic functions of their atomic
NUMBERS" (not their atomic
weights!)
1. Groups/Families
• vertical columns • elements in a group/family have
similar chem/phys prop's
• e- dot notation is the same in a
group
1. Groups/Families
2. Periods/Rows
• horizontal rows • elements in a period have
properties that change
progressively across the periodic
table
2. Periods/Rows
3. Group Numbers
-1-8 or 1-18 or A & B
-makes sense to number them 1-8 (based on e- dots)
when speaking in general
-When getting specific, “column 17” would obviously
mean the Halogens
1 2
3
4 5 6 7 8
4. Period Numbers
1-7 (correspond to "n", or principal quantum
number), which gives an idea of distance from
the nucleus
1
2
3
4
5
6
7
5. Major Categories
Inert (Noble)
Gases
METALS
Transition
TransitionMetals
Metals
Lanthanides
Actinides
Actinides
Non-Metals
6. Group Names
• a. Alkali Metals - Grp 1 - b/c they are
metals that can react w/ water,
forming alkaline sol'ns. Found
combined in nature; not uncombined.
• b. Alkaline Earth Metals - Grp 2 - Found
uncombined in nature
• c. Halogens - Grp 7 - "salt-formers"
• d. Noble (Inert) Gases - Grp 8 - Tend to
be unreactive due to their completed
octet of e-'s
6. Group Names
Alkali Metals
Alkaline Earth Metals
Chalcogens
Halogens
Noble
Gases
(Inert
Gases)
Important Trends
•
•
•
•
•
•
First Ionization Energy
Second Ionization Energy
Electron Affinity
Atomic Radii
Ionic Radii
Electronegativity
First Ionization Energy
• Def: “the min. am’t of energy required
to remove the most loosely held e-”
• top to bottom: decreases, since as
atomic size increases, e- from higher
energy levels are "shielded*" from the
nucleus and are therefore not as tightly
bound. (the "*shielding effect")
• left to right: increases, as elem's closer
to group 7 tend to want to gain e-'s.
(Noble gases have the highest F.I.E.)
F.I.E.
• Which of
these more
easily loses
e-’s?
• That’s the
one with
lower F.I.E.
First Ionization Energy
Second Ionization Energy
• Def: “the amount of energy
required to remove the
second e• Which is higher – FIE or SIE?
• top to bottom and left to
right - same trend as F.I.E.
S.I.E.
Second Ionization Energy
Electron Affinity
• Def: the amount of energy absorbed
when an e- is added to an isolated
gaseous atom forming a -1 ion
• Elements w/very neg. E.A.'s gain e-'s
easily to form anions.
• top to bottom - values become less
negative
• left to right - values become more
negative
Electron Affinity
Ionic Radii
• Defined as radius of the ion
• top to bottom - increase, due to the
increase in "n"
• left to right - decrease, due to the
addition of e- to same "n“
• Explanation: e- are added to same
“n”; there is a ‘tightening” of the
overall atomic radius due to
increased positive nuclear charge
For Metal Atoms forming
Metal Ions…
• Ionic radii smaller since e- is lost
from outermost level;
• ie: Na
For Nonmetal Atoms
forming Nonmetal Ions
• As an e- is added to a valence
shell, more room is needed (like
charges repel) and the ion is
larger
• ie: F
Electronegativity
• Def:
a measure of the relative
tendency of an atom to attract e-'s to
itself when it is chemically combined
with another atom
• Developed by Linus Pauling
• EN has no units, since it's relative
• top to bottom - decrease in EN
• left to right - increase in EN
Using Electronegativity
to Determine Bond Type
• there are two main types of
chemical bonds,
• a) ionic - have a diff. in EN of > 1.67
• b) covalent - have a diff. in EN of <
1.67
• COVALENT < 1.67 < IONIC
Calculate the Bond Type
• i.e.: What
kind of bond
is likely to
form in:
•
H2O
•
CO2
•
NaBr
•
MgO
For: H – O you would
look up the EN’s for H
and O and subtract
For: C – O you would
look up the EN’s for C
and O and subtract
For: Na – Br (same
process)
More
For: Mg – O (same
process)
on
this in
the
next
unit!
Miscellaneous Terms
•
•
•
•
anion - any negative ion
cation – any positive ion
isoelectronic –
(ie: N-3, O-2, F-1, Ne, Na+1, Mg+2, Al+3 )
What must this mean?
• For the next unit…
• Polyatomic ion – a group of atoms that
behaves as a single ion (ie: NH4+, NO3-,
CO3-2, SO4-2, etc etc)