Thursday 8 January 2015

4.5 Elements in a period

Properties of elements across Period 3
■ Period

The horizontal rows in the Periodic Table of Elements.

The proton number increase by one across the period from left to right.
■ Properties of elements across Period 3


The physical and chemical properties of the elements change gradually across the period as in the following table:
Element properties Na Mg Al Si P S Cl Ar
Electron arrangement 2.8.1 2.8.2 2.8.3 2.8.4 2.8.5 2.8.6 2.8.7 2.8.8
Electron valence 1 2 3 4 5 6 7 8

The animation below shows the explanation on the properties changes across Period 3.

■ This video contains information about the properties changes across Period 3.
Laboratory Activity 4.5.1: Determining the properties of oxide of elements in Period 3

Worked-example 4.5(a)
Choose true[ √ ] or false[ X ] for the statement given.
Statement Answer
The proton number increases by one across the period from left to right in the Periodic Table.
The atomic radius increases across the period from left to right in the Periodic Table.
The electronegativity increases across the period from left to right in the Periodic Table.
The melting point and boiling point increase and then decrease across the period from left to right in the Periodic Table.
The element oxide turns from basic to amphoteric and then to acidic across the period from left to right in the Periodic Table.





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