Question

atomic number quick check
which statement describes the properties of lanthanoids and actinoids? (1 point)
○ they are brittle and dull, and they tend to conduct both electricity and thermal energy.
○ they are malleable and lustrous, and they tend to be poor conductors of both electricity and thermal energy.
○ they are malleable and lustrous, and they tend to conduct both electricity and thermal energy.
○ they are brittle and dull, and they tend to be poor conductors of both electricity and thermal energy.

Explanation:

Lanthanoids and actinoids are part of the inner - transition metals. Metals in general have properties like being malleable (can be hammered into thin sheets), lustrous (shiny), and good conductors of electricity and thermal energy.

• The first option says they are brittle and dull, which is incorrect as metals are not brittle and dull in general.
• The second option says they are poor conductors, but metals are good conductors.
• The fourth option also has incorrect properties (brittle, dull, poor conductors) for metals.
• The third option correctly states the metallic properties of lanthanoids and actinoids.

Answer:

C. They are malleable and lustrous, and they tend to conduct both electricity and thermal energy.