Modern Periodic Table — Chemistry STD 11 Science — Question
Maharashtra BoardEnglish MediumSTD 11 ScienceChemistryModern Periodic Table3 Marks
Question
What is lanthanide and actinide series?
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Answer
$i.$ Lanthanide series: The fourteen elements after lanthanum $(Z = 57)$ i.e., from cerium $(Z = 58)$ to lutetium $(Z = 71)$ are named after their preceding member $(_{57}La)$ present in the third group and $6^{th}$ period and are called lanthanides. They are kept in separate series called lanthanide series at the bottom of the modem periodic table.
$ii.$ Actinide series: The fourteen elements after actinium i.e., from thorium $(Z = 90)$ to lawrencium $(Z = 103)$ are named after $_{89}Ac$ present in third period and $7^{th}$ group. They are kept in separate series called actinide series at the bottom of the modem periodic table.
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