MAIN GROUP ELEMENTS (GROUPS 1, 2, & 13 - 18)
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GROUP |
NAME |
ENDING e- |
# OF |
e- DOT |
WANTS TO (lose or |
CHARGE |
OXID- |
GETS (smaller or larger) WHEN ATOM TO ION? |
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1 |
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2 |
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13 |
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14
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15
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16
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17
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18
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ION:
UNIT 5 - THE PERIODIC LAW
History of the Periodic Table
I.
Mendeleev and Chemical Periodicity
A. Wanted to organize elements according to their
____________________
B. When elements were arranged in order of increasing
atomic mass*, similarities in chemical
properties appeared at regular
intervals (____________________)
C. *Several elements did not quite fit this pattern -
Mendeleev put elements with similar
____________________ in the same
column or group
D. 1871 - Mendeleev predicted the existence and
properties of several (then undiscovered)
elements. These elements were:
E. Within 15 years, those elements with those
properties had been discovered
II.
Moseley and the Periodic Law
A. When elements were arranged in order of increasing
___________________________________,
there was a distinct regular
pattern.
B. ____________________: The physical and
chemical properties of the elements are periodic
functions of their atomic
numbers.
C. In other words, when elements are arranged in order
of increasing atomic number, elements
with similar properties appear
at regular intervals.
D. Bottom line = elements in the same group have
similar properties
III.
Modern Periodic Table: arrangement of the elements in order of their
atomic numbers so that elements with
similar properties fall in the same group
Electron
Configuration and the Periodic Table
I.
Stability of Noble Gases
A. Noble gases undergo very few chemical reactions -
why?
B. Highest occupied energy level contains
________________________________________
C. Electrons in the highest occupied energy level are
what determines an element's _____________
II. Periods and Blocks of the Periodic Table
A. Horizontal row = ____________________; 7 on
modern Periodic Table
B. Length of period determined by the sublevels being
filled in that period
C. Period 1: only _____ sublevel being
filled; can hold a maximum of _____ electrons;
period contains _____ elements
D. Period 4: ____, ____, and ____ sublevels
being filled; s can hold ___ electrons, d can hold ___
electrons, & p can hold ___
electrons; total of _____ electrons;
Period 4 contains _____ elements
E. Period can be determined from the element's
electron configuration
1. Bromine: [Ar] 4s2
3d10 4p5
2. Highest number in front of
letter is the element's highest occupied _____________________ -
tells
which period the element is in
3. For bromine, _____ is
highest number, so it is in Period _____
III.
The "s" block elements: Groups 1 and 2
A. Group 1 - Alkali Metals
1. generalized outermost
energy level (valence) electron configuration:
2. silvery appearance
3. soft enough to cut with a
knife
4. not found in nature as free
elements - they're always part of a compound
5. with increasing atomic
number, melting point ______________________
B. Group 2 - Alkaline Earth Metals
1. generalized valence
electron configuration:
2. harder, stronger, more
dense than Group 1
3. also have higher melting
points than Group 1
4. less reactive than Group 1,
but still not found in nature as free elements
C. Exceptions: Hydrogen and Helium
1. Hydrogen (H)
a.
electron configuration:
b.
properties do not resemble those of any other element on the periodic table
2. Helium (He)
a.
electron configuration:
b. in
Group 18 because
IV.
The "d" block elements: Groups 3 - 12
A. called
B. have typical metallic properties: ductile,
malleable, shiny, solid, conduct electricity
C. less reactive than "s" block elements
D. found in nature as free elements
E. usual ending of electron configuration:
V.
The "p" block elements: Groups 13 - 18
A. "s" and "p" block elements
together referred to as _____________________________ elements
B. ending electron configurations of
__________________ through ___________________
C. properties vary greatly b/c there are metals,
metalloids, and nonmetals
D. Group 17 - Halogens
1. most reactive nonmetals
2. seven electrons in
outermost energy level
E. "p" block metals are harder and more
dense than "s" block , but not as hard or dense as the "d"
block metals
LOCATING MAIN GROUP ELEMENTS ON THE PERIODIC
TABLE
Given the
electron configuration or noble gas configuration for an element, it is
possible to determine its location on the Periodic Table without actually looking
at a Periodic Table.
* To tell
which period this element is in...
~ find the highest occupied energy level for this
element
You can do this by...
~ finding the largest coefficient number
The largest coefficient number is the number of the period where the element is
located.
* To tell
which "block" this element is in... (like "s" block,
"p" block, "d" block, etc)
~ find the highest occupied sublevel for this element
You can do this by...
~ finding the last lowercase letter written
The last lowercase letter written in the configuration is the "block"
where the element is located.
* To tell
which group this element is in...
~ find the highest occupied energy level for this
element
You can do this by...
~ finding the largest coefficient number
Then...
~ add up the exponents of the largest coefficient
number
This gives you the number of valence electrons in the element.
You will then know that 1 valence electron indicates that the element is in
Group 1, 2 valence electrons indicates that the element is in Group 2, 3
valence electrons indicates that the element is in Group 13, 4 valence
electrons indicates that the element is in Group 14, 5 valence electrons
indicates that the element is in Group 15, 6 valence electrons indicates that
the element is in Group 16, 7 valence electrons indicates that the element is
in Group 17, and 8 valence electrons indicates that the element is in Group 18.
Look at the
following example.
EXAMPLE:
[Ar] 4s2 3d10 4p5
It is
possible to tell the period, group, and "block" where this element is
located.
* Period -- largest coefficient number is 4, so element is in
Period 4
* Block-- last lowercase letter written is "p", so
element is in "p" block
* Group-- largest coefficient number is 4... 2 electrons in
4s, 5 electrons in 4p --> total of 7 valence electrons,
so this element is in Group 17.
Periodic Trends
Electronegativity/Electron Affinity (EN/EA):
measure of how much an atom wants to gain an electron
EN/EA Left
to Right across a Period: INCREASES (not including Noble Gases)
Why?
* Elements on the left side of the P.T. (metals) want to lose electrons. Elements on the right side of
the P.T. (nonmetals) want to gain
electrons. Trend does not include Noble
Gases because these
elements do not want to lose or gain
electrons.
EN/EA Top to
Bottom in a Group: DECREASES
Why?
* 
This interference (and resulting decreased “hold”) is referred to as the
SHIELDING EFFECT.
Ionization Energy (IE):
amount of energy required to remove an atom’s most loosely held electron
IE Left to
Right across a Period: INCREASES
Why?
* Elements on the left side of the P.T. (metals) want to lose electrons. Therefore, it will not require
much energy to remove an
electron. Elements on the right side of
the P.T. (nonmetals) want to gain
electrons. Consequently, a lot of energy will be needed
to remove (take away) an electron.
IE Top to
Bottom in a Group: DECREASES
Why?
*
Atomic
Radius (AR): distance from the nucleus to the H.O.E.L.
AR Top to Bottom in a Group: INCREASES
Why?
* There are more occupied energy levels as you move towards the
bottom of the P.T.
AR Left to
Right across a Period: DECREASES
Why?
*
Metallic Character:
how easily an atom will lose valence electrons (easier to lose = more
metallic = more reactive METAL)
Which metal loses its valence electron(s) most easily? Fr
Why?
* Francium has one valence electron. It
is more reactive than elements at the top of Group 1 because there are many
inner shell electrons that decrease the attraction the nucleus has for the
valence electrons.
Nonmetallic Character:
how easily an atom will gain electrons (easier to gain = more nonmetallic
= more reactive NONMETAL)
Which nonmetal gains electron(s) most easily? F
Why?
* Fluorine has seven valence electrons.
It is more reactive than elements at the bottom of Group 17 because
there are only a few inner shell electrons.
Consequently, the nucleus has a strong attraction for other electrons.