What is ionization energy ? How does it change in a period as well as in a group ?

What is electron negativity ? How does it change in a period as well as in a group ?

What do you mean by ionization enthalpy? How does it vary across a period and down a group?

What do you mean by ionization enthalpy? How does it vary across a period and down a group?

What do you mean by ionization enthalpy? How does it vary across a period and down a group?

What do you mean by ionization enthalpy? How does it vary across a period and down a group?

Define valency. How does it change across a period and on going down a group?

What is ionisation energy? How does ionisation energy vary along the period in the modern periodic table ?