Table of Contents
What is the periodic trend of first ionization energy?
The first ionization energy varies in a predictable way across the periodic table. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest first ionization energy, while francium has one of the lowest.
What is the trend in first ionization energy down a group on the periodic table?
On the periodic table, first ionization energy generally decreases as you move down a group. This is because the outermost electron is, on average, farther from the nucleus, meaning it is held less tightly and requires less energy to remove.
What is the trend for first ionization energy in groups and across periods?
In general, ionization energy increases across a period and decreases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant.
Why does first ionization energy decrease down a group?
Going down a group, the ionisation energy decreases. This is due to the shielding or screen effect of the outer electrons from the nucleus and so the attraction is weaker and they are more easily removed.
Why we see the trend in first ionization energy across periods?
The ionization energy of an element increases as one moves across a period in the periodic table because the electrons are held tighter by the higher effective nuclear charge.
What is ionization energy describe explain the trends in first ionization energies within groups and across periods in the periodic table provide examples?
First ionization energies decrease from top to bottom within a group and increase across a period from left to right. For example, the first ionization energy of rubidium is less than that of lithium.
Why does the first ionization energy decrease down a group?
How is ionization energy measured?
In physics, the ionization energy is measured in electron volts (eV) and measures how much energy is needed to remove one electron from one atom or molecule. In chemistry, the ionization energy is measured per mole of atoms or molecules and is expressed in kiloJoules per mole (kJ/mol).