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Successive Ionisation Energies

Successive ionisation energies increase because the remaining electrons are pulled closer to the nucleus after each electron is lost and the nuclear attraction on the remaining electrons increases.

The second ionisation energy is the energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions.

Mg⁺(g) → Mg²⁺(g) + e^-

Large jumps in ionisation energies provide evidence for electrons existing in shells. A large jump indicates the electron is being removed from a shell closer to the nucleus.
_{Successive ionisation energies of period 2 elements in kJmol^-1}

	e^-	1st I.E.	2nd I.E.	3rd I.E.	4th I.E.	5th I.E.	6th I.E.	7th I.E.	8th I.E.	9th I.E.
Li	1	520	7300
Be	2	900	1760	14850
B	3	800	2430	3660	25020
C	4	1090	2350	4620	6220	37830
N	5	1400	2860	4580	7480	9440	53270
O	6	1310	3390	5300	7470	10980	13330	71330
F	7	1680	3370	6050	8410	11020	15160	17870	92040
Ne	8	2080	3950	6120	9370	12180	15240	20000	23070	115380

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Specification: OCR Chemistry A (H032), AS-level, 3.1.1 Periodicity. Topic: Periodicity.

Key terms in this lesson

Ion: A positively or negatively charged atom or group of atoms, formed by the loss or gain of electrons.
Ionisation: The loss or gain of electrons by an atom or molecule to form a charged ion.
Electron shell: A main energy level occupied by electrons, given a principal quantum number n, with n = 1 closest to and lowest in energy relative to the nucleus.
Mole: The amount of substance that contains as many particles as there are atoms in exactly 12g of carbon-12.
Period: A horizontal row of the periodic table, containing elements with the same number of electron shells.

More in Periodicity

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