Transcript Ch. 13 Notes---Electrons in Atoms

Ch. 11.4 Notes---Atomic Properties and the Periodic Table
Valence Electrons and Electron Dot Notations
What are “valence electrons”?
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outer
most energy level
These are the electrons in the _________-_______
(or shell). These are responsible for chemical bonding.
All of the other electrons are called “core electrons”.
p electrons only.
s electrons and “___”
They will be “___”
Counting Valence Electrons
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Group A # = number of valence electrons
2 e-’s)
(only exception Helium = __
2 e-’s
Examples: Ca = __
’s
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5 e-’s
Nitrogen = __
2
d-block and f-block = ___valence e-’s
8 eArgon = __
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Drawing Valence Electrons
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“Electron-dot notation”: Electrons will be represented as dots
located around the symbol of the element in the pattern shown
below.
3
4
7
6
X
5
Examples: Nitrogen =
N
1
2
8
Hydrogen =
(important exception.... Carbon =
C
H
)
The Development of the Periodic Table
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Dmitri Mendeleev
_________________________:
constructed the 1st periodic table
Features of Mendeleev’s Periodic Table
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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
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Moseley
In 1913, Henry ______________
determined the atomic number, (#
p+ of the elements.
of ___),
– He then arranged the elements in the periodic table by increasing
atomic ____________.
number
– 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 _________/_________
Figure 11.35: Classification of elements as
metals, nonmetals, and metalloids.
Parts of the Periodic Table
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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
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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
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Nonmetals: located to the ___________
right
of the dark zig-zag line.
Properties of Nonmetals
dull surface
– _______
sulfur
brittle
– ______________
insulators
– good _______________
(or poor conductors)
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Metalloids: located on the border of the dark zig-zag line.
Examples: Silicon & Germanium
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Properties of Metalloids
semiconductors
(Used in computer chips)
___________________
Parts of the Periodic Table
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transition
d-block metals: “_________________
metals”
rare-earth
f-block metals: “Inner-transition metals” or “____________
metals”
Special Group/Family Names
Alkali
Group 1A: “_________ metals”
water
– React with _________
to form a base
Alkaline-earth
Group 2A: “________________ metals”
– Compounds areHalogens
used in batteries
Group 7A: “_________________”
– Used in some light fixtures
Noble
Group 8A (or 0 or 18): “_______ gases”
inert
– Don’t form compounds (_________)
Parts of the Periodic Table
Innertransition
metals
Trends in the Periodic Table
Atomic Size (Atomic Radius)
(See Fig. 11.36)
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increases
Moving Down a Group= the size of the atoms ________________
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more electrons to higher and
Why? You are adding ________
higher energy levels (farther and farther out.)
decreases
Moving Across a Period= the size generally ______________
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Why? You are adding more e- and p+ to the same energy
attraction of opposite
level. This causes more ______________
pulls the electron cloud inward.
charges and it __________
Figure 11.36: Relative atomic sizes for selected atoms.
Trends in the Periodic Table
Atomic Size vs. Ion Size
(See Figure 12.8)
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removing e-’s.
Cation = (___)
+ charged atom created by ___________
smaller
– Cations are ______________
than the original atom.
Metals generally form cations.
– _____________
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adding
− charged atom created by _____________
Anion = (___)
e-’s.
larger
– Anions are ____________
than the original atom.
Nonmetals
– _______________
generally form anions.
Trends in the Periodic Table
Atomic Size vs. Ion Size
Figure 12.8: Relative sizes of some ions and their parent atoms.
picometers
Trends in the Periodic Table
Ionization Energy
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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
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increases
Moving Across a Period= generally ________________
– Why?
Moving across a period takes us from metals to
nonmetals. More ionization energy is needed for
______________
nonmetals
compared to __________.
metals
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.
First Ionization Energies
Trends in the Periodic Table
“Successive Ionization Energies”
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“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 Figure 12.4)
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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.
Moving Down a Group= generally ______________
(less
decreases
attraction)
– Why?
The bonded electron is farther and farther out. These
e-’s will not be as attracted to the larger and larger
atoms.
Figure 12.4: Electronegativity values for selected elements.
Trends in the Periodic Table
Electronegativity
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increases
Moving Across a Period= generally _________________
– Why?
Again, the atoms are getting ________
smaller so they are
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 Figure 12.4 since
they do not ________
form _____________
compounds !
Determining the Ion Formed
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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?
a) Magnesium: ____
2 (gained or lost) b) Iodine: ____
1 (gained or lost)
3 (gained or lost)
c) Gallium:____
3 (gained or lost)
d) Boron:____