# Unit 3: Periodic Table

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15 Νοε 2013 (πριν από 4 χρόνια και 7 μήνες)

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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
-

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

Return

25 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
electron affinity.

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

The atomic radius increases as each new

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.

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.

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

Electronegativity Trend

The electronegativity increases in the
direction of the arrow.

This concludes the tutorial on
measurements.