Home
Class 11
CHEMISTRY
Give two reasons, why the number of elem...

Give two reasons, why the number of elements in the first period is only `2`?

Text Solution

Verified by Experts

It is because the `1 st` energy level can have only `1s` orbital which can have two electrons. When `n=1`,`l=0`.
Promotional Banner

Topper's Solved these Questions

  • APPENDIX - INORGANIC VOLUME 1

    CENGAGE CHEMISTRY|Exercise chapter-2 Multiple correct answer|2 Videos

  • APPENDIX - INORGANIC VOLUME 1

    CENGAGE CHEMISTRY|Exercise chapter-2 Single correct answer|3 Videos

  • APPENDIX - INORGANIC VOLUME 1

    CENGAGE CHEMISTRY|Exercise Exercise very short|70 Videos

  • ALKYNES

    CENGAGE CHEMISTRY|Exercise Exercises (Archives - Analytical and Desriptive Type)|4 Videos

  • ATOMIC STRUCTURE

    CENGAGE CHEMISTRY|Exercise Concept Applicationexercise(4.3)|19 Videos

Similar Questions

Explore conceptually related problems

The number of elements in the 4th period of periodic table is

Two elements X and Y have atomic numbers 10 and 14 respectively. Identify the group numbers of these elements in the periodic table.

Consider the elements of period 2 in the modern periodic table. Answer the following questions with explanation. Name the element which has same number of electrons in the first and second shell.

Give the names of the first three elements of the periodic table.

Assertion:In the present form of periodic table,the period number corresponds to the highest principal quantum number of the elements in the period. Reason:Elements having similar outer electronic configuration in their atoms belongs to same period.

CENGAGE CHEMISTRY-APPENDIX - INORGANIC VOLUME 1-Exercise Short
  1. Give four characteristics of s-block elements.

    Text Solution

    |

  2. Give four defects of Mandeleev's periodic table.

    Text Solution

    |

  3. Give two reasons, why the number of elements in the first period is on...

    Text Solution

    |

  4. On the basis of their electronic configuration, explain why alkali met...

    Text Solution

    |

  5. Give the order in which the melting points of halides of sodium decrea...

    Text Solution

    |

  6. Why are group 1 elements called alkali metals and group 17 are called ...

    Text Solution

    |

  7. Give four characteristics of d-block elements.

    Text Solution

    |

  8. Give any two features of Mendeleev's periodic table.

    Text Solution

    |

  9. How do the solubilities of alkaline earth metal sulphate and carbonate...

    Text Solution

    |

  10. why is melting point of LiCI lower than NaCI?

    Text Solution

    |

  11. Arrange the following in increasing order: a. BeCO(3),BaCO(3),CaCO(3...

    Text Solution

    |

  12. Which alkali metal carbonate is thermally unstable and why?

    Text Solution

    |

  13. Out of O and S which has higher electron affinity and why?

    Text Solution

    |

  14. What is diagonal relationship? Why does Li resemble with Mg?

    Text Solution

    |

  15. Give four characteristics of f-block elements. Why are they called inn...

    Text Solution

    |

  16. Why are electron affinities of noble gases zero? Arrange halogens in i...

    Text Solution

    |

  17. Arrange the species in each group in order of increasing ionisation en...

    Text Solution

    |

  18. What are the factors that affect electron affinity?

    Text Solution

    |

  19. Explain the term (a) screening effect (b) penetration effect and ( c )...

    Text Solution

    |

  20. a. Explain why the second ionisation energy of B is significantly high...

    Text Solution

    |