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.


Q1. What is an element?

Ans. It is a substance that cannot be split into other substances.

Water is not an element because it can be split into the gases oxygen and hydrogen. Oxygen and hydrogen are elements because they cannot be split. Every element has its own atomic number. This is the number of protons in its nucleus, which is balanced by the same number of electrons.