To get a good grasp on chemistry, you've got to understand the
Periodic Table of Elements. If you understand the elements of the
table, you'll be able to grasp a huge portion of information
about an element just by glancing at its placement on the chart.
An atom's position on the table is based on its atomic number,
which is derived from the number of protons in the nucleus. Since
the properties of the elements depend on changes in its
structure, which is mostly determined
by the electrons, ordering the atoms by number (indicating
the number of electrons as well as protons) will suggest certain
chemical properties of the element.
Properties of the Elements will depend on several conditions
including, arrangement of the elements, atomic radii, and the
element type.
Arrangement of the
Elements:
There are several characteristics of atoms as you go across or
down the rows and columns of the table. Properties will be
different depending on which way you travel along the table.
Horizontally:
The horizontal rows are called periods, and the chemical
properties of the elements change systematically throughout a
period. Some physical properties such as atomic size and the
number of electrons also change, as well as where the electrons
are located.
Columns:
Vertical columns of the table are called groups or families.
Their chemical properties do not change as we progress through
the column. In fact, going down columns shows us remarkably
similar properties. The reason behind this? All elements in a
family have the same number of electrons in their outermost
levels. Therefore, their physical properties might be different,
but chemical ones will be the same.
Atomic Radii:
Covalent atomic radius:
This is half of the measured internuclear distance in the solid
phase, it's a property of the periods (rows) of the table. Within
a single period on the table, the covalent atomic radius
generally decreases as the atomic number increases. Adding more
protons and corresponding electrons will cause an increase in the
covalent atomic radius.
Ionic radius:
A loss or gain of electrons by an atom will cause a change in the
size of the atom. A cation is smaller than the neutral
atom, while an anion is larger. Changing the number of
electrons brings a corresponding change in the energy levels and
sublevels.
Element Types:
Metals — tend to form positive ions when combining with
other elements and usually have high thermal and electrical
conductivity, metallic luster, and malleability.
Nonmetals — tend to form negative ions when combining
with other elements, or share electrons. When solid, they are
usually brittle, have low thermal and electrical conductivity,
and lack metallic luster.
Metalloids — are elements that have some properties
characteristic of metals and other properties characteristic of
nonmetals.
Now you try it...
