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Lesson 13
The Periodic Table of Elements
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•The Periodic Table of Elements
• During
this lesson, you will see many
things that you have seen before.
• So,
•I
we will take a different approach.
will ask a question.
• You
find the answer and write it.
• Have
your PTE handy.
• Ready?
•Who is Dmitri Mendeleev?
• He
was a Russian teacher who
found a way to organize the
elements.
• He wrote each element’s name
and properties on a separate card
and found a pattern used to
classify them.
• It is not exactly what we use today,
but he created the first PTE.
•How are the elements on the PTE
arranged?
• Mendeleev
arranged them
by their atomic masses.
• When he did this, he saw
that many elements in the
same columns had similar
properties.
• However, some did not fit
right.
• Today, they are arranged by
their atomic number.
•What are the horizontal rows
called?
• Each
horizontal row is called a
period, thus the name periodic
table of elements.
• The
7.
periods are numbered 1 to
• Elements
in each period
increase in atomic number
moving across the row from left
to right.
•What are the vertical columns
called?
• They
are called a group or chemical
family.
• Groups
are numbered from 1 to 18.
• Elements
in the same group have
similar chemical properties.
• Their
properties are similar because all
the elements in a group have the
same number of valence electrons.
•What are valence electrons?
• Valence
electrons are the electrons in
the outermost energy level.
• The
number and arrangement of
valence electrons tells how atoms of
one element will combine with atoms of
other elements to form compounds.
•Which elements are the main
group elements?
•
Groups 1 and 2 and 13-18 are the main group
elements.
•What are groups 3-12 called and
why?
•They are the transition elements.
•They include the transition metals,
which
are
generally
hard
solids
with high melting points.
•Many transition metals change
color
when
they
lose
electrons
and
become charged.
•Which groups have how many
valence electrons?
• Group
1 has one valence
electron.
• Group
• So
2 has two.
on and so forth.
• This
is true for the main
group elements.
•Where on the PTE are the metals,
gases, non-metals, alkali metals,
etc.?
•With the exception of hydrogen, the
elements
on
the
left
side
of
the
PTE
are
metals.
•The elements on the right side are nonmetals.
•What are properties of metals?
• Metals• Are solid
at room temperatureexcept for Mercury, which is a liquid
• Are malleable and ductile, which
means they can be shaped and
drawn into wire form
• Have luster
• Have high conductivity for
electricity and heat
• Tend to lose electrons in chemical
reactions
•What are the properties of
nonmetals?
• Nonmetals• Are mostly gases while others are
solid or liquid at room temperature
• Are brittle when they are solid
• Most are dull in solid form
• Are poor conductors of electricity
and heat
• Tend to gain electrons in chemical
reactions
•What is reactivity in relation to
electrons?
• Reactivity is how likely an element is
to form compounds with other
elements.
• The most chemically active metals
are in Group 1, the alkali metals.
• They have one valence electron
that allows them to easily combine
with nonmetals.
•What are the alkaline earth metals?
•
•
•
The alkaline earth metals are the elements in Group
2.
They are highly reactive but are slightly less reactive
and harder than the Group 1 metals.
The reactivity of both Group 1 and 2 metals increases
with increasing atomic number.
•What is the jagged line on the PTE
for?
•
•
•
•
That line is there to designate the are between the
metals and nonmetals.
Elements found there are called metalloids.
They have properties of both metals and nonmetals.
Boron and silicon are both metalloids.
•What are the halogens?
•
•
•
•
•
The halogens are the nonmetals in Group 17.
They are the most reactive nonmetals
Reactivity in nonmetals increases as atomic number
deceases, so fluorine is the most reactive nonmetal.
Astatine is the least reactive.
The halogens react with the alkali metals to form salts.
Elements in the halogen family exist in all three states
of matter. Fl and Cl are gases, Br and I are liquids,
and I and At are solids.
•What are the noble gases?
•
•
•
•
•
•
The noble gases are the last column-Group 18.
They are also known as the inert gases.
They are the least reactive elements because they
have eight valence electrons, and all elements want
to have eight.
Originally, they were thought to be unable to react
chemically.
In 1962, however, a compound containing xenon
and fluorine was made.
Most noble gases only form compounds under
extreme conditions.