Which of the following are members of 15 naturally occurring metallic chemical elements whose atomic numbers are between 57 and 71?

The correct answer is Lanthanides.Key Points

• The atomic number of lanthanide is in the 57-71 range
• It is also called lanthanoid.
• It is any of the series of 14 consecutive chemical elements in the periodic table from lanthanum to lutetium i.e. atomic numbers 57–71 with 57 (Lanthanum) and 71 (Lutetium).
• Scandium and yttrium are rare-earth metals.

Additional Information

• Actinides are the 14 elements with atomic numbers from 89 to 103.
  • They are named after the first element in the series, actinium.
  • The actinides group includes mostly man-made elements with only a few exceptions such as uranium and thorium.
  • The actinides are most known for the elements uranium and plutonium which are used in nuclear reactors and nuclear bombs.
• Alkali metals belong to the s-block elements occupying the leftmost side of the periodic table.
  • Alkali metals readily lose electrons, making them the most reactive elements on earth.
  • In general ‘alkali’ refers to the basic or alkaline nature of their metal hydroxides.
  • The compounds are called alkali metals because when they react with water they usually form alkalies which are strong bases that can easily neutralize the strong acids.​
• Halogens contain 2 gases, one liquid, and 2 solids.
  • Halogens are elements of group 17 in the periodic table consisting of five elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
  • Fluorine and chlorine are gases.