The d-and f-Block Elements — Chemistry STD 12 Science — Question

→ All the lanthanoids are silvery white soft metals and tarnish rapidly in air.
→ The hardness increases with increasing atomic number, samarium being steel hard.
→ Their melting points range between 1000 to 1200 K but samarium melts at 1623 K.
→ They have typical metallic structure and are good conductors of heat and electricity.
→ Density and other properties change smoothl except for Eu and Yb and occasionally for Str and Tm.