How do the following properties change in group - 1 and in the third period? Explain with example.
(d) Nature of oxides.

Explanation

Nature of oxides: All the elements of 1A group are called alkali metals. Their oxides are basic in nature. They dissolve in water to give basic solutions.
Ex : `Na_(2)O, K_(2)O` etc.
`Na_(2)O + H_(2)O rarr 2NaOH`
The basic nature of these oxides increases from top to bottom in 1A group.
In 3rd period the basic nature of oxides decreases and acidic nature increases form left to right.
`{:(Na_(2)O,MgO,Al_(2)O_(3),SiO_(2), P_(4)P_(10),SO_(3),Cl_(2)O_(7)),("Strong basic oxide","Weak basic oxide", "Amphoteric oxide","Weak acidic oxide","Acidic oxide","Strong acidic oxide","Strong acidic oxide"):}`.