The element with atomic number 37 belongs to which block in the modern periodic table?  

CONCEPT:

Periodic Table and Blocks

• The modern periodic table is divided into four blocks: s-block, p-block, d-block, and f-block.
• The classification into blocks is based on the type of orbital (s, p, d, or f) in which the last electron enters.
• The s-block elements have their outermost electron in an s orbital, p-block in a p orbital, d-block in a d orbital, and f-block in an f orbital.

EXPLANATION:

• The atomic number 37 corresponds to the element Rubidium (Rb).
• The electronic configuration of Rubidium is:
  1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹
• The last electron enters the 5s orbital, which is part of the s-block.
• The s-block is located on the left side of the periodic table and includes groups 1 (alkali metals) and 2 (alkaline earth metals).

Therefore, the element with atomic number 37 (Rubidium) belongs to the s-block in the modern periodic table.