The periodic table is a tabular arrangement
of the chemical elements, ordered by their
atomic number (From previous videos you already
know that atomic number is the number of protons
in each atom)
The rows of the table are called periods,
and the columns are called groups.
The table you are seeing in this video is
a simplified version of the periodic table.
Elements in the first three groups are generally
metals (or in terms of electronics, conductors).
The forth group, which is highlighted by orange
are semiconductors.
And elements in groups five to seven are generally
non-metals.
Elements of the eighth group are called noble
gases.
Noble gases are extremely stable atoms, since
they have full valence electron shells.
Question 02
Now, lets take a quick look at a simple question
to make sure you have fully understood, the
concepts of atomic number, groups and periodic
table.
Imagine we don’t have access to the periodic
table, and we haven’t memorized it.
We have an element with the atomic number
17.
We also have 4 other elements and we only
know their atomic numbers.
How do we know which one of these elements
has the same characteristics of element with
atomic number 17?
Pause the video and think about it.
OK.
As you may already found, first we have to
see which group these elements belong to.
I start with the element with atomic number
17.
As we discussed earlier, electrons fill shells
and sub-shells from inside starting at shell
K, and electrons of the last shell indicate
the group of an element.
Electrons of the last shell are valence electrons.
So element with the atomic number 17 belongs
to group 7 of the periodic table, since it
has 7 electrons in its valence shell.
Element 32 belongs to group 4, element 15
belongs to group 5, atomic number 11 belongs
to group 1, and element with atomic number
35 belongs to group 7 which is the same group
as element 17.
So, by having atomic number we can find valuable
information about the elements of the periodic
table.
