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

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".