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Sodium and aluminium have atomic numbers...

Sodium and aluminium have atomic numbers 11 and 13 respectively. They are separated by one element in the periodic table and have valencies 1 and 3 respectively . Chlorine and potassium are also separated by one element in the periodic table. Their atomic numbers are 17 and 19 respectibely, buth both have a valency of 1. Explain why.

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BHARATI BHAWAN (ENGLISH)-PERIODIC CLASSIFICATION OF ELEMENTS -LONG - ANSWER QUESTIONS
  1. What were the early attempts to classify the elements ?

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  2. What is the significance of the blank spaces in Mendeleev's periodic t...

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  3. What is meant by the statement , 'Properties of elements are a periodi...

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  4. Why is the atomic number of an element more important than its atomic ...

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  5. Define the following : (a) group (b) period , (c) , representative ...

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  6. State how atomic size varies from left to right in a period and from t...

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  7. What is the basic difference between Mendeleev's periodic table been o...

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  8. How have the shortcomings of Mendeleev's periodic table been overcome ...

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  9. Describe briefly Mendeleev's periodic table along with its merits.

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  10. Write the electronic structures of the atoms of (a) potassium (b) lith...

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  11. What is the difference between valence electrons and valency of an ele...

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  12. Sodium and aluminium have atomic numbers 11 and 13 respectively. They ...

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  13. The atomic number of an element X is 17. Predict (a) its valency, (b) ...

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  14. Two elements X and Y belong to groups 1 and 2 respectively in the same...

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  15. Define periodic law. Why was it necessary to changes the basis of clas...

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  16. Explain the terms atomic radius, ionization energy and electron affini...

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