doubt in the chem Syllabus??

[The Ultimate]

The Syllabus says: "Describe the change from metallic to no-metallic character across a period."
What does this mean????

And can anyone help me understand it????

PLus: How is chromatography used to purify substances???(by separating impurities) An example??? The procedure???

Aluminium hydroxide is amphoteric. How would it react with NaOH? What are the products?

Is neutralisation REDOX??????

THANX IN ADVANCE!!

 

[LoayTYS]

The Syllabus says: "Describe the change from metallic to no-metallic character across a period."
What does this mean????

And can anyone help me understand it????

PLus: How is chromatography used to purify substances???(by separating impurities) An example??? The procedure???

Aluminium hydroxide is amphoteric. How would it react with NaOH? What are the products?

Is neutralisation REDOX??????

THANX IN ADVANCE!!

Q1) As you go from left to right in a period in the periodic table, the non metallic properties increase and the metallic properties decrease

Q2) Chromatography is not actually used to purify substances, it is used to test for purity ad food,drugs and medicines need to be 100% pure,if chromatography is being used then the result should be only one well defined spot being formed on the chromatogram paper

Q3) Aluminium hydroxide would produce sodium aluminate (Al(OH)3 + NaOH ----> Na[Al(OH)4] (this link will give you more info http://www2.uni-siegen.de/~pci/versuche ... 44-10.html)

Q4) No it is not , however the reaction between a metal and an acid is a redox reaction

Hope this helps

 

[M.S.Princess93]

I really dont understand well the answer about the chromotgraphy can u simplify what u said ?

 

[LoayTYS]

I really dont understand well the answer about the chromotgraphy can u simplify what u said ?

OK, for food products,drugs and medicines need to be safe and 100% pure,they should not contain any impurities
we can test the purity by 3 methods
A)Test the melting point:-the melting point should not be at a range but should be sharp and does not change during melting.
If it is impure then it would melt at a LOWER RANGE OF MELTING POINTS
B)Test the boiling point:-the boiling point should not be at a range but should be sharp and does not change during boiling.
If it is impure then it would boil at a HIGHER RANGE OF BOILING POINTS
C)Chromatography:-If the substance is pure then only one spot will be formed on the chromatogram paper,however if impure then you will get many spots at different levels.
Here is an image to simplify what I am talking about
http://www.hferrier.co.uk/standard/topi ... graphy.gif
in the diagram S,G,F are pure but H is not (it contains both G and F)

 

[M.S.Princess93]

thank u very much , it really helped

 

[The Ultimate]

hmm.... thanx guys :|