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Ch. 14 Notes---Chemical Periodicity
Valence Electrons and Electron Dot Notations
What are “valence electrons”?
•
outer
most energy level
These are the electrons in the _________-_______
(or shell).
p electrons only.
s electrons and “___”
• They will be “___”
Counting Valence Electrons
•
Group A # = number of valence electrons
2 e-’s)
(only exception Helium = __
2 e-’s Nitrogen = __
5 e-’s Argon = __
8 e-’s
Examples: Ca = __
•
2
d-block and f-block = ___valence
e-’s
Drawing Valence Electrons
•
“Electron-dot notation”: Electrons will be represented as dots
located around the symbol of the element in the pattern shown
below.
8 3
2
7
X
5
1
4 6
Examples: Nitrogen =
N
Hydrogen =
(Important Exception: Helium)
H
He
Valence Electrons On The Periodic Table
1
8
2
3 4 5 6 7
Sucktastic!
Assume 2
The Development of the Periodic Table
•
Dmitri Mendeleev
_________________________:
constructed the 1st periodic table
Features of Mendeleev’s Periodic Table
(See p.390)
•
•
blank _________
spaces for “missing elements”. Later when
He left ______
these elements were discovered, he filled in the gaps.
He arranged the elements in columns and rows according to their
properties
__________________.
Elements with similar properties were in the
same horizontal row.
•
predict
He was able to accurately ___________
the properties of the missing
rows
elements based on the properties of the elements in similar _______.
•
atomic ___________.
mass
He ordered the elements by increasing __________
Features of the Modern Periodic Table
(See Fig. 14.2)
•
•
•
•
Moseley
In 1913, Henry ______________
determined the atomic number, (#
p+ of the elements.
of ___),
– He then arranged the elements in the periodic table by increasing
number
atomic ____________.
– This switched the position of some elements. This is how the
modern periodic table is arranged today.
Periods or Series
Horizontal Rows = ____________
Groups
Vertical Columns = ____________
or Families
groups
families have similar properties.
Elements in the same _________/_________
Parts of the Periodic Table
•
left of the dark zig-zag line running
Metals: located to the _______
f
through the “p-block”. This includes the elements in the ___-block.
Properties of Metals
– shiny surface
malleable (you can pound it into a flat sheet)
– ______________
ductile
– ______________
(you can draw it into a thin wire)
conductors
– good _______________
(heat/electricity travels through it easily)
Parts of the Periodic Table
•
Nonmetals: located to the ___________
right
of the dark zig-zag line.
Properties of Nonmetals
dull surface
– _______
brittle
– ______________
insulators
– good _______________
(or poor conductors)
•
Metalliods: located on the border of the dark zig-zag line.
Examples: Silicon & Germanium
–
Properties of Metalliods
semiconductors
(Used in computer chips)
___________________
Parts of the Periodic Table
•
•
d-block metals: “_________________
transition
metals”
rare-earth metals”
f-block metals: “Inner-transition metals” or “____________
Special Group/Family Names
•
Alkali metals”
Group 1A: “_________
water to form a base
– React with _________
•
Alkaline-earth metals”
Group 2A: “________________
– Compounds are used in batteries
•
Halogens
Group 7A: “_________________”
– Used in some light fixtures
•
Noble gases”
Group 8A (or 0 or 18): “_______
inert
– Don’t form compounds (_________)
Parts of the Periodic Table
Trends in the Periodic Table
Atomic Size (Atomic Radius)
(See Fig. 14.10)
•
increases
Moving Down a Group= the size of the atoms ________________
–
•
more of electrons to higher and
Why? You are adding ________
higher energy levels (farther and farther out.)
decreases
Moving Across a Period= the size generally ______________
–
Why? You are adding more e- and p+ to the same energy
attraction
level. This causes more ______________
of opposite
pulls the electron cloud inward.
charges and it __________
Trends in the Periodic Table
Atomic Size vs. Ion Size
(See Fig. 14.8)
•
removing e-’s.
Cation = (___)
+ charged atom created by ___________
smaller
– Cations are ______________
than the original atom.
Metals generally form cations.
– _____________
•
adding
Anion = (___)
e-’s.
− charged atom created by _____________
larger
– Anions are ____________
than the original atom.
Nonmetals
– _______________
generally form anions.
Trends in the Periodic Table
Atomic Size vs. Ion Size
Trends in the Periodic Table
Ionization Energy
(See Table 14.1 & Fig. 14.12)
•
•
remove
Ionization energy is the energy required to _______________
the
outer most electron in an atom.
decreases
Moving Down a Group= _______________
(less energy is
needed)
– Why?
You are trying to remove an electron that is farther
and farther out (for larger and larger atoms). These e-’s
attracted
are not as ________________to
the nucleus.
less attracted it is to its e-’s.
– In general, the larger the atom, the ____
Trends in the Periodic Table
Ionization Energy
•
increases
Moving Across a Period= generally ________________
– Why?
Moving across a period takes us from metals to
nonmetals. More ionization energy is needed for
nonmetals
metals
______________
compared to __________.
cations it won’t take as
– Also, since metals generally form _________,
much energy to remove it’s outer most electron.
– Remember that as you move across the period, the atoms get
smaller and therefore ______
more attracted to the electrons.
_________
Trends in the Periodic Table
“Successive Ionization Energies”
(See Table 14.1)
•
“Successive Ionization Energies” means the energy required to
2nd or a _____
3rd electron from an atom.
remove a _____
more and ______
more
– Removing more and more e-’s requires ______
energy.
– Why?
tightly _________
bound
The remaining e-’s are more _________
to
the nucleus.
Trends in the Periodic Table
Electronegativity
(See Table 14.2)
•
•
0 – 4.0 which
Electronegativity is a relative value (from_________)
compares how much an atom is attracted to the e-’s in a
chemical bond.
____________
decreases
Moving Down a Group= generally ______________
(less
attraction)
– Why?
The bonded electron is farther and farther out. These
e-’s will not be as attracted to the larger and larger
atoms.
Trends in the Periodic Table
Electronegativity
•
increases
Moving Across a Period= generally _________________
– Why?
smaller so they are
Again, the atoms are getting ________
more attracted to the bonding electrons.
_______
– Also, moving across a period takes us from metals to
anions
nonmetals. Since nonmetals generally form _________,
they
gain
tend to __________
e-’s anyway, and this makes them
highly
________________
attracted to e-’s when forming a chemical
bond.
Noble __________
gases
– ___________
are not listed in Table 14.2 since
form _____________
compounds !
they do not ________
Determining the Ion Formed
•
Atoms try to achieve a ________
noble ______
gas configuration when
forming an ion. (This makes them more stable.)
– Locate the nearest noble gas and count how many “places” it is
away, but remember that you can skip over the d-block!!
– This amount will be the same as the # of e-’s either gained or lost
by the atom when forming an ion.
Practice Problem: How many electrons are gained or lost when
forming an ion from the following elements?
2 (gained or lost) b) Iodine: ____
1 (gained or lost)
a) Magnesium: ____
3 (gained or lost)
c) Gallium:____
3 (gained or lost)
d) Boron:____