For Aluminium (Al) (atomic number: 13, mass number: 27), which one among the following statements is NOT correct?

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NDA-II 2024 (GAT) Official Paper (Held On: 01 Sept, 2024)
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  1. Number of electrons present in Al is 13
  2. Number of protons present in Al is 13
  3. Number of neutrons present in Al is 14
  4. The valency of Al is 2

Answer (Detailed Solution Below)

Option 4 : The valency of Al is 2
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CONCEPT:

Atomic Structure of Aluminium (Al)

  • Aluminium (Al) has an atomic number of 13 and a mass number of 27.
  • The atomic number (Z) represents the number of protons in the nucleus of an atom.
  • The mass number (A) represents the total number of protons and neutrons in the nucleus.
  • The number of electrons in a neutral atom is equal to the number of protons.
  • The valency of an element typically refers to its ability to combine with other atoms, often determined by the number of electrons in its outer shell.

EXPLANATION:

  • For Aluminium (Al):
    • Number of protons (atomic number, Z) = 13
    • Number of electrons in a neutral atom = 13
    • Number of neutrons = Mass number (A) - Atomic number (Z) = 27 - 13 = 14
    • The electron configuration of Aluminium is 2, 8, 3, meaning it has 3 electrons in its outer shell.
    • The valency of Aluminium is 3 because it tends to lose 3 electrons to achieve a stable electron configuration similar to the nearest noble gas (Neon).
  • Among the given options, the statement "The valency of Al is 2" is NOT correct. The correct valency of Aluminium is 3.

Therefore, the statement that is NOT correct is: "The valency of Al is 2".

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