The element with atomic number 57 belongs to:
d-block
To identify the block of the modern periodic table an element belongs to, we look at the sub-shell in which the last electron enters.
The element with atomic number 57 is lanthanum (La). Its electronic configuration is [Xe] 5d1 6s2. The last differentiating electron occupies the 5d sub-shell rather than the 4f sub-shell, so lanthanum is placed in the d-block, in Group 3 of Period 6, and is often treated as the first member of the lanthanide series.
s-block elements have their last electron in an s sub-shell, p-block in a p sub-shell and f-block in an f sub-shell.
Hence, d-block.
Similar Questions
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Important Questions from Classification of Elements and Periodicity in Properties
- Which one of the following statements about alkaline earth metals is NOT true ?
- What element is a greenish yellow gas with a characteristic smell at room temperature?
- In the periodic table, as one goes down the group, which property doesn't change?
- Which of the following is a copper ore?
- Which scientist invented the Periodic table?
