Classification of elements in the Periodic Table
Sharifah Mona Abdul Aziz Abdullah
Abdul Al-Hafiz Ismail
Centre for Pre-University Studies
Universiti Malaysia Sarawak
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The periodic table shows all of the known elements
in order of increasing atomic number.
Horizontal row of periodic table is called period.
Periods are arranged horizontally across the
periodic table, labeled as rows 1 – 7.
These elements have the same number of valence
The periodic table is organized to group elements
with similar properties in vertical columns.
Groups are arranged vertically down the periodic
table, labeled as column 1 – 18.
These elements have the same number electrons in
the outer most shells, the valence shell.
Elements can be grouped into 3 classes based
on their general properties:
Metal – shiny and conduct electricity
Non-metal – do not conduct electricity
Metalloids – semiconductors
They are in group 1 of periodic table
They are shiny, soft and can be cut with a knife
They have 1 valence electron
The most reactive metals (react violently with
Reactivity increasing down the group
Never found as free elements in nature
Alkaline Earth Metal
They are in Group 2 of periodic table
They are less reactive than alkali metal
They are shiny and silvery-white in
They have 2 valence electrons
Thay are never found uncombined in
They are in Group 3 to 12 of periodic table
Good conductors of heat and electricity
The compounds of transition metals are usually brightly coloured
Have variable oxidation number
Sc Ti V Cr Mn Fe Co Ni Cu Zn
They are in Group 17 of periodic
They have 7 valence electron
The most reactive of the non-metals
React with alkali metal to form salts.
Reactivity decreasing down the group
They are in group 18 of the
Also known as inert gases
All exist in gases at room
Non-reactive because they have a
full valence shell (which is 8)