Unit 3: Periodic Table

awfulhihatΠολεοδομικά Έργα

15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

96 εμφανίσεις


Unit 3: Periodic Table

Chapter 6

Objectives

21

Understand
the historical background of the periodic table including
such contributions of Newlands, Mendeleev, and
Moseley


22

Use
the periodic table to predict properties of certain
elements


23

Identify
the difference between periods and
groups


24

Identify
where main group, metals, metalloids, non
-
metals, alkali,
alkaline
-
earth, halogen, noble gases, transition metals, lanthanides
(rare earth metals) and actinides exist on the periodic table along
with their characteristics and electron
configurations


25

Define
and apply the periodic law to the trends on the periodic table
including atomic radius, ionization energy, and electron
affinity/electronegativity


21 Historical Background on the
Periodic Table


The Periodic Table was original designed by
John Newlands and was published in the
1860s.


He also proposed an idea known as the Law of
Octaves to help explain his setup for the table.


More extensive work was done on the
Periodic Table by Dmitri Mendeleev.


He arranged the table by atomic mass.


He left blanks where he felt elements should
belong even though they were not discovered
yet.

Mendeleev’s Periodic Table


Historical Background Continued


While Mendeleev’s table was the first that
resembled our current model, there were
some flaws.


None of the noble gases were present.


There were some discrepancies Mendeleev could
not explain in certain properties.


It did not account for isotopes.

Historical Background Continued


In 1914, Henry Moseley rearranged the
Periodic Table by atomic number.


By doing this, he eliminated the
discrepancies that Mendeleev could not
explain.


Moseley’s table is the model used today with
the elements found after 1914 added to the
table.

22 Characteristics of the Table


The Periodic Table was carefully designed to
provide as much information as possible.



The table is ordered into:


Periods: horizontal rows


Groups: vertical columns


Blocks: S, P, D, or F

23,24 Sections of the Table


There are certain sections of the Periodic
Table that have common properties.


Metals


Metalloids


Non
-
metals


Main Group Elements

Metals


Shiny


Form positive ions


Ductile


Malleable


High melting and
boiling points


Good conductors


Heat and energy

Return

Non
-
Metals


Make up the majority
of the crust,
atmosphere and living
organisms


Low melting and
boiling points


Form negative ions


Low densities


If solid, tend to be dull
and brittle


Poor conductors


Both heat and energy

Return

Metalloids


Semi
-
conductors



Contain some
metallic properties



Contain some non
-
metallic properties

Return

Main Group Elements



Made up of the S and
P blocks




Consists of some of
the most common
elements.

Return

Groups and Blocks

Alkali Metals

Alkaline Earth Metals

Transition Metals

Halogens

Noble Gases

Actinide Series

Lathanide

Series

Alkali Metals


Highly reactive


Rarely found in the
elemental form


Soft metals


Low densities


Make +1 ions


Last electron is
always a s
1

Return

Alkaline Earth Metals



Always from +2 ions



Last electron is
always an s
2



High melting points



Reactive but not as
violent as the alkali
metals


Return

Halogens


Highly reactive


Form
-
1 ions


All but astatine can
form a diatomic
molecule


Common in acids


Used as disinfectants
and in pesticides

Return

Noble Gases


Odorless, colorless
gases


Outer (valence)
energy level is full


Very low reactivity


Melting and boiling
points are low and
very close together


Cryogenic
refrigerants

Return

Transition Metals


Form the D
-
Block of
the Periodic Table


Magnetic Properties


1 or more unpaired
electrons


High melting and boiling
points


Can from +1, +2, +3
ions


Generally solid


Return

Lanthanide Series



Make up the 4f block


Typically used in lasers


Sometimes referred to
as the rare earth
metals


Though actually found in
high concentrations in
the crust


Superconductors


Batteries and magnets

Return

Actinide Series


Make up the 5f
-
block


Most are man
-
made


Thorium and uranium are
the only two the occur
naturally with any
abundance.


Radioactive



Return

25 Periodic Law


Certain properties follow periodic law.


Periodic law refers to the increasing or
decreasing of a trend as one progresses
across a period or group on the Periodic
Table.


Three of the most common trends that are
monitored and follow periodic law are
atomic radius, ionization energy, and
electron affinity.

Atomic Radius


Atomic radius refers to the size of the
electron cloud surrounding the nucleus.


The atomic radius increases as each new
energy level is added.


While electrons are being added to an
energy level, electron shielding allows for the
affects the size of the atom.

Electron Shielding


As electrons start filling
energy levels, the nucleus
holds them close.


As more are added, the
inner ring prevents the
nucleus from pulling the
outer ring too close (it
shields the positive
charge).


The nucleus will pull the
energy level slightly closer
though as you progress
across the table.

Atomic Radius Trend


The atomic radius increases in the
direction of the arrow.

Ionization Energy


Ionization energy is the energy required to
remove an electron from an atom.



The larger the atom, the more difficult it is
for the nucleus to hold onto its electrons.



Smaller atoms can hold onto electrons much
easier.

Ionization Energy Trend


The ionization energy increases in the
direction of the arrow.

Electronegativity


Electronegativity refers to how well an
atom attracts electrons.



Smaller atoms have more nuclear charge
to attract electrons.



As that large atoms have a difficult time
holding onto their electrons, they do not
readily attract electrons.

Electronegativity Trend


The electronegativity increases in the
direction of the arrow.


This concludes the tutorial on
measurements.


To try some practice problems, click here.


To return to the objective page,
click
here.


To exit the tutorial, hit escape.

Definitions
-
Select the word to return to the tutorial