Q11. What are the lanthanides?

Ans. The lanthanides are a group of 15 elements in the middle of the periodic table that take their name from lanthanum. They are all shiny silvery metals and often occur naturally together. They all have two electrons in their outer electron shells. This makes them chemically similar- they are all very reactive.


Q7. What is a metal?

Ans. Most people can recognize a metal. It is hard, dense and shiny and goes ‘ping’ when you strike it with something else made of metal. It also conducts both electricity and heat well. Chemists define a metal as an electropositive element, which basically means that metals easily lose negatively charged electrons. It is these lost,’ free’ electrons that makes metals such excellent conductors of electricity.

Noble Gases.

Q3. What are noble gases?

Ans. Group 0 is the furthest right-hand column of the periodic table. This group is called the noble gases, because they have full-up outer electron shells and so nobly stay aloof from any reaction with ‘base’ metals or any other substance. They are sometimes called inert gases.