Chemistry AS ES CI 2.5
- Created by: A.B.
- Created on: 17-02-14 11:30
View mindmap
- ES Atoms and Ions CI 2.5
- First Ionisation Enthalpy
- The first ionisation enthalpy is the energy needed to remove one electron from one mole of isolated gaseous atoms of an element.
- X (g) -> X+ (g) + e-
- Always positive (energy must be supplied)
- Trends
- The elements at the peaks are all in Group 0. It is difficult to remove an electron from these atoms with full outer shells and the elements are very unreactive.
- The elements at the troughs are all in group 1 (alkali metals ). These atoms have only one outer shell electron and are relatively easy to ionise. They are all very reactive elements.
- How does it vary across a period?
- First ionisation enthalpy increases as atomic number increases.
- The nuclear charge increases going across the period and the electrons are being added to the same shell so there is greater attraction between the nucleus and electrons.
- First ionisation enthalpy increases as atomic number increases.
- How does it vary down a group?
- Decrease down the group
- Attraction between nucleus and outermost electron decreases (electron further with more shielding) -> easier to remove
- Decrease down the group
- Successive Ionisation Enthalpies
- The second and subsequent ionisation enthalpies involve the removal of an electron from a positive ion.
- Patterns
- Ionisation enthalpies increase as successive electrons are removed.
- After an electron is removed, the remaining electrons are attracted more strongly to the nucleus.
- There is a sharp jump in ionisation enthalpy when an electron is removed from a full electron shell.
- Ionisation enthalpies increase as successive electrons are removed.
- The first ionisation enthalpy is the energy needed to remove one electron from one mole of isolated gaseous atoms of an element.
- First Ionisation Enthalpy
Comments
No comments have yet been made