Unit 4: Up Close: The Periodic Table of Elements

Section 1: Representative Elements

* Introduction
* Properties
* Alkali Metals
* Alkali Earth Metals
* Aluminum

Introduction

You have seen the perodic table in your chemistry class, studied the symbols
of the elements, and probably used the numbers in some claculations. But
what exactly are the elements of the Periodic Table? In this section, we
will study the elements known as the representative metals, which make up
the first two families of the perodic table.

Properties of Metals

Many properties of metals are attributed to the way their atoms are bonded.
Each metal has electrons that when the right conditions exist, could move up
to empty enery levels. A small amount of enery is required to move these
electrons to the empty enery levels that each metal atom possess.
Similarily, a small loss in energy could easily drop the upgraded electron
to its former enery leverl. These properties account for the metallic bonds
between metal atoms. Metallic bonds result from the easy flow of electrons
between the closely spaced enery levels of metal atoms. Therefore each metal
atom is bonded to a sea of electrons.

Also, the flow of electrons around the metal atoms give the properties of
malleability (the ability of a metal to be shaped without breaking) and
ductility ( the ability of metal to be drawn into a wire.) The metal atoms
can withstand the stress of being moved against each other since they have
electrons in common.

Alkali Metals

Alkali Metals make up the first family of the perodic table. Lithium and
sodium are some examples. The alkali metals tend to give up one electron in
a chemical compound. This accounts for their high reactivity with out
elements. Therefore they are not found in nature, and difficult to obtain in
their pure form. They react with air, water, and other substances.

The properties that make the alkali metals disguish from other families in
the periodic table is that they are soft, have many metallic properties, are
soft enough to be cut with a knife, are soluble in water, can conduct heat
and electricity, and the solutions of these elements are colorless. Also,
the alkali metals react vigorously in water.Sodium Reacts Violently With
Water Lab For example, the reaction between water and sodium produces sodium
hydroxide, hydrogen gas, and a good deal of energy. Also, the name of this
family comes from the properties of alkali metals to form hydroxides with
water. Compounds containing hydroxide is alkali or is basic.

Alkali Earth Metals

Alkali earth metals make up the second family of the perodic table. Calcium
and barium are some examples. The alkali earth metals also called alkaline
earth metals usually give up two electrons in a chemical compound. However,
like alkai metals, they are too reactive to be found in their pure state in
nature. Alkali earth metals are also denser and not as soft as alkali
metals.

Magnesium, an alkali earth metal, can be used as a firework. When exposed to
a flame, magnesium produces a bright white light.

Aluminum

Aluminum is the third most abundant element in the Earth's crust and usually
is found combined with oxygen. Alumiun yields three electrons in a compound.
Aluminum was once more expensive that gold or silver. This was due to fact
that it was difficult to extract in its pure form. In the late nineteenth
century, better processes were developed, making it cheaper. Alumium is a
good electrical conducter, highly reactive, can form lightwieght alloys, and
is malleable.