Ionisation Energy Flashcards
What is the definition of the first ionisation energy
Energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to from 1 mole of gaseous 1+ ions
Why is this process endothermic
Energy is put in to ionise an atom or molecule
What three factors affect ionisation energy
Nuclear charge
Electron shells
Shielding
How does nuclear charge affect ionisation energy
More protons in the nucleus the more positively charged the nucleus is so the stronger the attraction for the electrons
How does electron shells affect ionisation energy
More electrons shells the greater the atomic radius becomes so the distance increases
An electron close to the nucleus will be more attracted to the nucleus and require greater ionisation energy
How does shielding affect ionisation energy
As the number of electrons increase between the outer shell electron and the nucleus , the attraction between the outer shell electron and nucleus decreases so less ionisation energy is required
What does high ionisation energy mean
Strong attraction between electron and nucleus so more energy is needed to overcome the attraction and remove the electron
Why does ionisation energy decrease as you go down the group
Shielding increases as there are more shells so more electrons between the outer shell electron and the nucleus
More shells means the atomic radius increases so outer shell electron is further away from the nucleus
What does decrease in ionisation energy prove
Evidence that electrons shells really exist
What is the formulae for successive ionisation energy
X(n-1)—>Xn+ + e-
What’s the definition of second ionisation energy
Energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to from 1 mole of gases 2+ ions
What does a graph of successive ionisation energy provide evidence for
Shell structure of atoms
Why does ionisation energy within each shell increase
Electrons are being removed from an increasingly positive ions so less repulsion with remaining electrons so there held more strongly by the nucleus
Why do bigs jumps in ionisation energy happen
They happen when new shell is broken into so an electron is being removed from a shell closer to the nucleus
How does the graph tell you the group
By counting how many electrons are removed before first big jump
