Define ionisation energy .

An ionisation energy ( IE ) is the energy required to remove one mole of electrons from one mole of gaseous atoms of an element, forming one mole of gaseous 1+ ions.

Ionisation energies are measured under standard conditions of .......... K and .......... kPa, and have units of .......... .

Ionisation energies are measured under standard conditions of 298 K and 101 kPa, and have units of kJ mol -1 .

Why are ionisation energies always positive values?

Ionisation is endothermic, so energy must be supplied to overcome the force of attraction between the electron and the positive nucleus.

True or False? The first ionisation energy involves removing an electron from a gaseous 1+ ion.

False. The first IE involves removing an electron from a neutral gaseous atom, producing a gaseous 1+ ion. The second IE involves removal from a gaseous 1+ ion.

Write the equation for the first ionisation energy of calcium.

Ca (g) → Ca + (g) + e - IE 1 = +590 kJ mol -1

The second ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous .......... ions to form one mole of gaseous .......... ions.

The second ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

Write the equation for the second ionisation energy of calcium.

Ca + (g) → Ca 2+ (g) + e - IE 2 = +1145.4 kJ mol -1

True or False? The equation Ca (g) → Ca 2+ (g) + 2e - correctly represents an ionisation energy.

False. Ionisation energies must be written one step at a time, removing one mole of electrons per equation. This equation represents two separate ionisation steps combined.

Why must atoms in ionisation energy equations be in the gaseous state?

Ionisation energy is defined specifically for gaseous species. Including solid or liquid atoms would incorporate the energy of vaporisation, which is not part of the IE definition.

Define electron shielding .

An electron shielding is the reduction in effective nuclear charge experienced by outer electrons, caused by repulsion from inner-shell electrons that partially block the attraction of the nucleus.

Across a period, first ionisation energy generally .......... because nuclear charge .......... while shielding remains roughly .......... and atomic radius .......... .

Across a period, first ionisation energy generally increases because nuclear charge increases while shielding remains roughly constant and atomic radius decreases .

Explain why first ionisation energy decreases down a group.

Down a group, atomic radius increases and shielding increases as more electron shells are added. Both effects weaken the attraction between the nucleus and outer electrons, outweighing the increased nuclear charge.

True or False? Successive ionisation energies for a given element always increase.

True. Removing each electron leaves an increasingly positive ion, so the remaining electrons are held more tightly by the nucleus and require more energy to remove.

Why is the first ionisation energy of oxygen lower than that of nitrogen?

Oxygen has two electrons paired in the 2p x orbital. Spin-pair repulsion makes it easier to remove one of these paired electrons, lowering the first IE relative to nitrogen, where each 2p orbital holds only one electron.

A large jump in successive ionisation energies indicates an electron is being removed from a new .......... closer to the nucleus. The number of electrons removed before the jump equals the number of .......... electrons.

A large jump in successive ionisation energies indicates an electron is being removed from a new inner shell closer to the nucleus. The number of electrons removed before the jump equals the number of valence electrons.

Why is the first ionisation energy of boron lower than that of beryllium?

Boron's outer electron is in the 2p sub-shell, which is at a higher energy level and further from the nucleus than beryllium's 2s outer electrons, so less energy is needed to remove it.

True or False? A large jump between the first and second ionisation energies of an element indicates it belongs to Group 1.

True. Only one valence electron is removed before the large jump, indicating the element has one outer-shell electron, a defining feature of Group 1 elements.

State four factors that affect ionisation energy.

Nuclear charge: higher charge increases IE. Distance from the nucleus: greater distance decreases IE. Electron shielding: more inner shells decrease IE. Spin-pair repulsion: paired electrons in an orbital decrease IE.

Define successive ionisation energies .

Successive ionisation energies are the energies required to remove each subsequent mole of electrons from one mole of a gaseous element, one electron at a time from an increasingly positive ion.

How can successive ionisation energy data be used to determine an element's group?

Identify the largest jump between consecutive ionisation energies. The number of electrons removed before that jump equals the number of valence electrons, which gives the group number for s- and p-block elements.

As successive electrons are removed, ionisation energies increase because the ion becomes more .......... , increasing the attraction between the nucleus and the .......... electrons.

As successive electrons are removed, ionisation energies increase because the ion becomes more positive , increasing the attraction between the nucleus and the remaining electrons.

True or False? If the largest jump in successive ionisation energy data occurs between the 3rd and 4th IE, the element has 3 valence electrons.

True. The jump occurs because the 4th electron is removed from a new inner shell. The 3 electrons removed before the jump are the valence electrons.

Identify the Period 3 element with a large jump between IE 7 and IE 8 .

Seven electrons are removed before the large jump, indicating 7 valence electrons and Group 17. The Period 3 element in Group 17 is chlorine (Cl), with configuration 1s 2 2s 2 2p 6 3s 2 3p 5 .

To deduce electronic configuration from successive IE data, locate the .......... increase between consecutive IEs. Electrons removed before this jump represent the .......... electrons.

To deduce electronic configuration from successive IE data, locate the largest increase between consecutive IEs. Electrons removed before this jump represent the valence electrons.

Why does a large jump occur in successive ionisation energies?

The large jump occurs when an electron is removed from a new inner shell closer to the nucleus. These electrons experience less shielding and stronger nuclear attraction, so much more energy is required to remove them.

True or False? The position of the large jump in successive ionisation energy data indicates an element's period.

False. The position of the large jump indicates the number of valence electrons and therefore the element's group, not its period.

Explain why a large jump between IE 2 and IE 3 suggests an element is in Group 2.

Two electrons are removed before the large jump, indicating 2 valence electrons. For s- and p-block elements, the number of valence electrons equals the group number, so the element belongs to Group 2.

A LevelChemistryCambridge (CIE)Flashcards1. Atomic StructureIonisation Energy

Ionisation Energy (Cambridge (CIE) A Level Chemistry): Flashcards

Exam code: 9701

1/27

0Still learning

Know0

FrontDefining Ionisation Energy
Define ionisation energy.

Was this flashcard helpful?

Cards in this collection (27)

Define ionisation energy.
An ionisation energy (IE) is the energy required to remove one mole of electrons from one mole of gaseous atoms of an element, forming one mole of gaseous 1+ ions.
Ionisation energies are measured under standard conditions of .......... K and .......... kPa, and have units of .......... .
Ionisation energies are measured under standard conditions of 298 K and 101 kPa, and have units of kJ mol^-1.
Why are ionisation energies always positive values?
Ionisation is endothermic, so energy must be supplied to overcome the force of attraction between the electron and the positive nucleus.
True or False?
The first ionisation energy involves removing an electron from a gaseous 1+ ion.
False.
The first IE involves removing an electron from a neutral gaseous atom, producing a gaseous 1+ ion. The second IE involves removal from a gaseous 1+ ion.
Write the equation for the first ionisation energy of calcium.
Ca (g) → Ca⁺ (g) + e^- IE₁ = +590 kJ mol^-1
The second ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous .......... ions to form one mole of gaseous .......... ions.
The second ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
Write the equation for the second ionisation energy of calcium.
Ca⁺ (g) → Ca²⁺ (g) + e^- IE₂ = +1145.4 kJ mol^-1
True or False?
The equation Ca (g) → Ca²⁺ (g) + 2e^- correctly represents an ionisation energy.
False.
Ionisation energies must be written one step at a time, removing one mole of electrons per equation. This equation represents two separate ionisation steps combined.
Why must atoms in ionisation energy equations be in the gaseous state?
Ionisation energy is defined specifically for gaseous species. Including solid or liquid atoms would incorporate the energy of vaporisation, which is not part of the IE definition.
Define electron shielding.
An electron shielding is the reduction in effective nuclear charge experienced by outer electrons, caused by repulsion from inner-shell electrons that partially block the attraction of the nucleus.
Across a period, first ionisation energy generally .......... because nuclear charge .......... while shielding remains roughly .......... and atomic radius ...........
Across a period, first ionisation energy generally increases because nuclear charge increases while shielding remains roughly constant and atomic radius decreases.
Explain why first ionisation energy decreases down a group.
Down a group, atomic radius increases and shielding increases as more electron shells are added. Both effects weaken the attraction between the nucleus and outer electrons, outweighing the increased nuclear charge.
True or False?
Successive ionisation energies for a given element always increase.
True.
Removing each electron leaves an increasingly positive ion, so the remaining electrons are held more tightly by the nucleus and require more energy to remove.
Why is the first ionisation energy of oxygen lower than that of nitrogen?
Oxygen has two electrons paired in the 2p^x orbital. Spin-pair repulsion makes it easier to remove one of these paired electrons, lowering the first IE relative to nitrogen, where each 2p orbital holds only one electron.
A large jump in successive ionisation energies indicates an electron is being removed from a new .......... closer to the nucleus. The number of electrons removed before the jump equals the number of .......... electrons.
A large jump in successive ionisation energies indicates an electron is being removed from a new inner shell closer to the nucleus. The number of electrons removed before the jump equals the number of valence electrons.
Why is the first ionisation energy of boron lower than that of beryllium?
Boron's outer electron is in the 2p sub-shell, which is at a higher energy level and further from the nucleus than beryllium's 2s outer electrons, so less energy is needed to remove it.
True or False?
A large jump between the first and second ionisation energies of an element indicates it belongs to Group 1.
True.
Only one valence electron is removed before the large jump, indicating the element has one outer-shell electron, a defining feature of Group 1 elements.
State four factors that affect ionisation energy.
1. Nuclear charge: higher charge increases IE.
2. Distance from the nucleus: greater distance decreases IE.
3. Electron shielding: more inner shells decrease IE.
4. Spin-pair repulsion: paired electrons in an orbital decrease IE.
Define successive ionisation energies.
Successive ionisation energies are the energies required to remove each subsequent mole of electrons from one mole of a gaseous element, one electron at a time from an increasingly positive ion.
How can successive ionisation energy data be used to determine an element's group?
Identify the largest jump between consecutive ionisation energies. The number of electrons removed before that jump equals the number of valence electrons, which gives the group number for s- and p-block elements.
As successive electrons are removed, ionisation energies increase because the ion becomes more .......... , increasing the attraction between the nucleus and the .......... electrons.
As successive electrons are removed, ionisation energies increase because the ion becomes more positive, increasing the attraction between the nucleus and the remaining electrons.
True or False?
If the largest jump in successive ionisation energy data occurs between the 3rd and 4th IE, the element has 3 valence electrons.
True.
The jump occurs because the 4th electron is removed from a new inner shell. The 3 electrons removed before the jump are the valence electrons.
Identify the Period 3 element with a large jump between IE₇ and IE₈.
Seven electrons are removed before the large jump, indicating 7 valence electrons and Group 17. The Period 3 element in Group 17 is chlorine (Cl), with configuration 1s² 2s² 2p⁶ 3s² 3p⁵.
To deduce electronic configuration from successive IE data, locate the .......... increase between consecutive IEs. Electrons removed before this jump represent the .......... electrons.
To deduce electronic configuration from successive IE data, locate the largest increase between consecutive IEs. Electrons removed before this jump represent the valence electrons.
Why does a large jump occur in successive ionisation energies?
The large jump occurs when an electron is removed from a new inner shell closer to the nucleus. These electrons experience less shielding and stronger nuclear attraction, so much more energy is required to remove them.
True or False?
The position of the large jump in successive ionisation energy data indicates an element's period.
False.
The position of the large jump indicates the number of valence electrons and therefore the element's group, not its period.
Explain why a large jump between IE₂ and IE₃ suggests an element is in Group 2.
Two electrons are removed before the large jump, indicating 2 valence electrons. For s- and p-block elements, the number of valence electrons equals the group number, so the element belongs to Group 2.

Sign up to unlock flashcards

By signing up you agree to our Terms and Privacy Policy

Previous:Electrons, Energy Levels & Atomic OrbitalsNext:Relative Masses of Atoms & Molecules