Concept of Atomic
Number that Led to the
Synthesis of New Elements
in the Laboratory
INTRODUCTION QUARTER 1- MODULE 2
PERIODIC TABLE OF ELEMENTS
is
a rows and columns arrangement
of the chemical elements. It is widely
used in chemistry, physics, and other
sciences, and is generally seen as an
icon of chemistry.
KEY POINTS:
 Henry
Gwyn-Jeffreys
Moseley was an English
physicist who
demonstrated that the
atomic number, the
number of protons in an
atom, determines most of
the properties of an
element.
KEY POINTS:
In
1919, Ernest Rutherford
successfully carried out a
nuclear transmutation
reaction a process of
transforming one
element or isotope into
another element
KEY POINTS:
Dmitri
Mendeleev
created a classification of elements based
on their atomic weight. He found that
organizing the elements at the time by
their calculated weight demonstrated a
periodic pattern of both physical and
chemical properties, such as luster,
physical state, reactivity to water, and
others.
HOW TO READ
PERIODIC TABLE OF
ELEMENTS
Group in Periodic Table

Groups are the columns of the periodic table, and periods are the
rows. There are 18 groups.
The

Alkali Metals (Group 1)
The alkali metals consist of all of the elements in group one with the
exception of hydrogen. These elements are extremely reactive and
for this reason, are usually found in compounds. In addition, they are
water-sensitive (they react violently with water), so they must be
stored in oil. The most reactive alkali metal is francium and it
decreases as you go up the group. This means lithium is the least
reactive. Physically, the alkali metal family is silvery, white, and light.
They also have low melting and low boiling points.
The Alkaline Earth Metals
(Group 2)
 The
alkaline earth metals are the second most
reactive family on the periodic table (following
behind the alkali metals). Moreover, they are strong
reducing agents which means they donate
electrons in chemical reactions. They are also good
thermal and electrical conductors. Physically, they
have low density, low melting point, and a low
The Transition Metals
(Groups 3-11)
The
transition metals typically form two or
more oxidation states. They have low
ionization energies and high conductivity. In
addition, they have high melting points, high
boiling points, and high conductivity.
Physically they are both metallic and
Post Transition Metal
The
post transition metals are located in
between the transition metals and the
metalloids. At standard temperature, they
are in a solid state of matter. They tend to
have a high density as well as high
conductivity. Physically they are malleable
and ductile.
The Metalloids
 The
metalloids display properties of both metals
and non-metals. For example, metals are good
conductors and non-metals are poor
conductors. This means metalloids are
semiconductors (only conducts electricity at
high temperatures.). Also, they are more brittle
than metals but less brittle than non-metals.
Physically they can be either shiny or dull and
are typically ductile and malleable.
The Halogens (Group 17)

The name halogen means “salt formers” in greek. This is
evident in nature as halogens interact with metals to form
various salts. On another note, the halogens are a unique
group of elements. They are the only periodic family that
contains elements in the three states of matter at standard
temperature. There are 6 halogens and they are located in
group 17. These elements include fluorine (F), chlorine (Cl),
bromine (Br), iodine (I), and astatine (At). They are highly
reactive, highly electronegative, and highly toxic non-metals.
Noble Metals
 The
noble metals consist of ruthenium (Ru), osmium
(Os), rhodium (Rh), iridium (Ir), Pd, platinum (Pt), gold
(Au), silver (Ag). Like the noble gases, they are inert
due to having a complete valence shell. In addition,
noble metals have catalytic tendencies. Also, they are
very resistant to corrosion, tarnishing, and oxidation.
Finally, like many of the other metals, they are soft and
ductile.
Noble Gases (Group 18)
 The
noble gases, also called aerogens, are inert
gases. Some examples include argon, krypton, and
neon. They can be found in group eighteen on the
periodic table. Likewise, this means they have a
complete valence shell. For this reason, they are
stable and relatively unreactive. Furthermore, the
noble gases have low boiling points and low
melting points. Physically they are colorless and
have no smell.
WHAT IS PERIOD?
The
elements are arranged in seven
horizontal rows, in order of increasing
atomic number from left to right and
top to bottom. The rows are called
periods, and they are numbered from 1
to 7
HOW TO READ ELEMENTS
WHAT IS ATOMIC NUMBER?
The
atomic number is the number of protons
(positively charged particles) in an atom.
WHAT
The
IS ATOMIC MASS?
atomic mass is a weighted average of
all of the isotopes of that element, in which
the mass of each isotope is multiplied by the
abundance of that particular isotope.