Qu'est-ce qui va se passer quand on met plus d'électrons dans les éléments comme le francium, ils vont devenir plus forts ou plus faibles ?
Extensions

Although francium is the heaviest alkali metal that has been discovered, there has been some theoretical work predicting the physical and chemical characteristics of hypothetical heavier alkali metals. Being the first period 8 element, the undiscovered element ununennium (element 119) is predicted to be the next alkali metal after francium and behave much like their lighter congeners; however, it is also predicted to differ from the lighter alkali metals in some properties. Its chemistry is predicted to be closer to that of potassium or rubidium instead of caesium or francium. This is unusual as periodic trends, ignoring relativistic effects would predict ununennium to be even more reactive than caesium and francium. This lowered reactivity is due to the relativistic stabilisation of ununennium's valence electron, increasing ununennium's first ionisation energy and decreasing the metallic and ionic radii; this effect is already seen for francium. This assumes that ununennium will behave chemically as an alkali metal, which, although likely, may not be true due to relativistic effects. The relativistic stabilisation of the 8s orbital also increases ununennium's electron affinity far beyond that of caesium and francium; indeed, ununennium is expected to have an electron affinity higher than all the alkali metals lighter than it. Relativistic effects also cause a very large drop in the polarisability of ununennium. On the other hand, ununennium is predicted to continue the trend of melting points decreasing going down the group, being expected to have a melting point between 0 °C and 30 °C.

The stabilisation of ununennium's valence electron and thus the contraction of the 8s orbital cause its atomic radius to be lowered to 240 pm, very close to that of rubidium (247 pm), so that the chemistry of ununennium in the +1 oxidation state should be more similar to the chemistry of rubidium than to that of francium. On the other hand, the ionic radius of the Uue ion is predicted to be larger than that of Rb, because the 7p orbitals are destabilised and are thus larger than the p-orbitals of the lower shells. Ununennium may also show the +3 and +5 oxidation states, which are not seen in any other alkali metal, in addition to the +1 oxidation state that is characteristic of the other alkali metals and is also the main oxidation state of all the known alkali metals: this is because of the destabilisation and expansion of the 7p spinor, causing its outermost electrons to have a lower ionisation energy than what would otherwise be expected. Indeed, many ununennium compounds are expected to have a large covalent character, due to the involvement of the 7p electrons in the bonding.

Not as much work has been done predicting the properties of the alkali metals beyond ununennium. Although a simple extrapolation of the periodic table (by the Aufbau principle) would put element 169, unhexennium, under ununennium, Dirac-Fock calculations predict that the next element after ununennium with alkali-metal-like properties may be element 165, unhexpentium, which is predicted to have the electron configuration 5g 6f 7d 8s 8p 9s. This element would be intermediate in properties between an alkali metal and a group 11 element, and while its physical and atomic properties would be closer to the former, its chemistry may be closer to that of the latter. Further calculations show that unhexpentium would follow the trend of increasing ionisation energy beyond caesium, having an ionisation energy comparable to that of sodium, and that it should also continue the trend of decreasing atomic radii beyond caesium, having an atomic radius comparable to that of potassium. However, the 7d electrons of unhexpentium may also be able to participate in chemical reactions along with the 9s electron, possibly allowing oxidation states beyond +1, whence the likely transition metal behaviour of unhexpentium. Due to the alkali and alkaline earth metals both being s-block elements, these predictions for the trends and properties of ununennium and unhexpentium also mostly hold quite similarly for the corresponding alkaline earth metals unbinilium (Ubn) and unhexhexium (Uhh). Unsepttrium, element 173, may be an even better heavier homologue of ununennium; with a predicted electron configuration of 6g, it returns to the alkali-metal-like situation of having one easily removed electron far above a closed p-shell in energy, and is expected to be even more reactive than caesium.

The probable properties of further alkali metals beyond unsepttrium have not been explored yet as of 2019, and they may or may not be able to exist. In periods 8 and above of the periodic table, relativistic and shell-structure effects become so strong that extrapolations from lighter congeners become completely inaccurate. In addition, the relativistic and shell-structure effects (which stabilise the s-orbitals and destabilise and expand the d-, f-, and g-orbitals of higher shells) have opposite effects, causing even larger difference between relativistic and non-relativistic calculations of the properties of elements with such high atomic numbers. Interest in the chemical properties of ununennium, unhexpentium, and unsepttrium stems from the fact that they are located close to the expected locations of islands of stability, centered at elements 122 (Ubb) and 164 (Uhq).
Francium

On prédit également que le francium présentera certaines différences en raison de son poids atomique élevé, ce qui amène ses électrons à se déplacer à des fractions considérables de la vitesse de la lumière et rend ainsi les effets relativistes plus importants. Contrairement à la tendance à la diminution des électronégativités et des énergies d'ionisation des métaux alcalins, l'électronégativité et l'énergie d'ionisation du francium sont prédites comme étant plus élevées que celles du césium, en raison de la stabilisation relativiste des électrons 7s ; de plus, son rayon atomique devrait être anormalement faible. Ainsi, contrairement à ce que l'on pourrait attendre, le césium est le métal alcalin le plus réactif, et non le francium. Toutes les propriétés physiques connues du francium s'écartent également des tendances claires observées du lithium au césium, telles que la première énergie d'ionisation, l'affinité électronique et la polarisabilité anionique, bien que, en raison du manque de données connues sur le francium, de nombreuses sources fournissent des valeurs extrapolées, ignorant le fait que les effets relativistes rendent la tendance du lithium au césium inapplicable au francium. Parmi les rares propriétés du francium qui ont été prédites en tenant compte de la relativité, on trouve l'affinité électronique (47,2 kJ/mol) et l'enthalpie de dissociation de la molécule de Fr (42,1 kJ/mol). La molécule CsFr est polarisée en Cs Fr, ce qui montre que la sous-couche 7s du francium est beaucoup plus fortement affectée par les effets relativistes que la sous-couche 6s du césium. De plus, on s'attend à ce que le superoxyde de francium (FrO) présente un caractère covalent important, contrairement aux autres superoxydes des métaux alcalins, en raison des contributions de liaison provenant des électrons 6p du francium.
### Query ###
Qu'est-ce qui va se passer quand on met plus d'électrons dans les éléments comme le francium, ils vont devenir plus forts ou plus faibles ?

### Main Text ###
Extensions

Although francium is the heaviest alkali metal that has been discovered, there has been some theoretical work predicting the physical and chemical characteristics of hypothetical heavier alkali metals. Being the first period 8 element, the undiscovered element ununennium (element 119) is predicted to be the next alkali metal after francium and behave much like their lighter congeners; however, it is also predicted to differ from the lighter alkali metals in some properties. Its chemistry is predicted to be closer to that of potassium or rubidium instead of caesium or francium. This is unusual as periodic trends, ignoring relativistic effects would predict ununennium to be even more reactive than caesium and francium. This lowered reactivity is due to the relativistic stabilisation of ununennium's valence electron, increasing ununennium's first ionisation energy and decreasing the metallic and ionic radii; this effect is already seen for francium. This assumes that ununennium will behave chemically as an alkali metal, which, although likely, may not be true due to relativistic effects. The relativistic stabilisation of the 8s orbital also increases ununennium's electron affinity far beyond that of caesium and francium; indeed, ununennium is expected to have an electron affinity higher than all the alkali metals lighter than it. Relativistic effects also cause a very large drop in the polarisability of ununennium. On the other hand, ununennium is predicted to continue the trend of melting points decreasing going down the group, being expected to have a melting point between 0 °C and 30 °C.

The stabilisation of ununennium's valence electron and thus the contraction of the 8s orbital cause its atomic radius to be lowered to 240 pm, very close to that of rubidium (247 pm), so that the chemistry of ununennium in the +1 oxidation state should be more similar to the chemistry of rubidium than to that of francium. On the other hand, the ionic radius of the Uue ion is predicted to be larger than that of Rb, because the 7p orbitals are destabilised and are thus larger than the p-orbitals of the lower shells. Ununennium may also show the +3 and +5 oxidation states, which are not seen in any other alkali metal, in addition to the +1 oxidation state that is characteristic of the other alkali metals and is also the main oxidation state of all the known alkali metals: this is because of the destabilisation and expansion of the 7p spinor, causing its outermost electrons to have a lower ionisation energy than what would otherwise be expected. Indeed, many ununennium compounds are expected to have a large covalent character, due to the involvement of the 7p electrons in the bonding.

Not as much work has been done predicting the properties of the alkali metals beyond ununennium. Although a simple extrapolation of the periodic table (by the Aufbau principle) would put element 169, unhexennium, under ununennium, Dirac-Fock calculations predict that the next element after ununennium with alkali-metal-like properties may be element 165, unhexpentium, which is predicted to have the electron configuration 5g 6f 7d 8s 8p 9s. This element would be intermediate in properties between an alkali metal and a group 11 element, and while its physical and atomic properties would be closer to the former, its chemistry may be closer to that of the latter. Further calculations show that unhexpentium would follow the trend of increasing ionisation energy beyond caesium, having an ionisation energy comparable to that of sodium, and that it should also continue the trend of decreasing atomic radii beyond caesium, having an atomic radius comparable to that of potassium. However, the 7d electrons of unhexpentium may also be able to participate in chemical reactions along with the 9s electron, possibly allowing oxidation states beyond +1, whence the likely transition metal behaviour of unhexpentium. Due to the alkali and alkaline earth metals both being s-block elements, these predictions for the trends and properties of ununennium and unhexpentium also mostly hold quite similarly for the corresponding alkaline earth metals unbinilium (Ubn) and unhexhexium (Uhh). Unsepttrium, element 173, may be an even better heavier homologue of ununennium; with a predicted electron configuration of 6g, it returns to the alkali-metal-like situation of having one easily removed electron far above a closed p-shell in energy, and is expected to be even more reactive than caesium.

The probable properties of further alkali metals beyond unsepttrium have not been explored yet as of 2019, and they may or may not be able to exist. In periods 8 and above of the periodic table, relativistic and shell-structure effects become so strong that extrapolations from lighter congeners become completely inaccurate. In addition, the relativistic and shell-structure effects (which stabilise the s-orbitals and destabilise and expand the d-, f-, and g-orbitals of higher shells) have opposite effects, causing even larger difference between relativistic and non-relativistic calculations of the properties of elements with such high atomic numbers. Interest in the chemical properties of ununennium, unhexpentium, and unsepttrium stems from the fact that they are located close to the expected locations of islands of stability, centered at elements 122 (Ubb) and 164 (Uhq).

### Supplementary Text ###
Francium

On prédit également que le francium présentera certaines différences en raison de son poids atomique élevé, ce qui amène ses électrons à se déplacer à des fractions considérables de la vitesse de la lumière et rend ainsi les effets relativistes plus importants. Contrairement à la tendance à la diminution des électronégativités et des énergies d'ionisation des métaux alcalins, l'électronégativité et l'énergie d'ionisation du francium sont prédites comme étant plus élevées que celles du césium, en raison de la stabilisation relativiste des électrons 7s ; de plus, son rayon atomique devrait être anormalement faible. Ainsi, contrairement à ce que l'on pourrait attendre, le césium est le métal alcalin le plus réactif, et non le francium. Toutes les propriétés physiques connues du francium s'écartent également des tendances claires observées du lithium au césium, telles que la première énergie d'ionisation, l'affinité électronique et la polarisabilité anionique, bien que, en raison du manque de données connues sur le francium, de nombreuses sources fournissent des valeurs extrapolées, ignorant le fait que les effets relativistes rendent la tendance du lithium au césium inapplicable au francium. Parmi les rares propriétés du francium qui ont été prédites en tenant compte de la relativité, on trouve l'affinité électronique (47,2 kJ/mol) et l'enthalpie de dissociation de la molécule de Fr (42,1 kJ/mol). La molécule CsFr est polarisée en Cs Fr, ce qui montre que la sous-couche 7s du francium est beaucoup plus fortement affectée par les effets relativistes que la sous-couche 6s du césium. De plus, on s'attend à ce que le superoxyde de francium (FrO) présente un caractère covalent important, contrairement aux autres superoxydes des métaux alcalins, en raison des contributions de liaison provenant des électrons 6p du francium.

### Draft ###

### 1. Query Parsing

"Qu'est-ce qui va se passer quand on met plus d'électrons dans les éléments comme le francium, ils vont devenir plus forts ou plus faibles ?"

Translation: "What happens when we put more electrons into elements like francium, will they become stronger or weaker?"

? Semantic ambiguity: "plus d'électrons" = additional electrons? Or hypothetical heavier elements?

### 2. Domain Contextualization  

● Francium (Z=87) - heaviest alkali metal, extreme relativistic effects
● Periodic trends: normal alkali metal behavior up to Cs, then breakdown
● Theoretical chemistry: predictions for superheavy elements beyond 119

Key challenge: relativistic quantum mechanics dominates for Z>119

### 3. Physical Constraints Analysis

**Electronic structure constraints:**
- 8s orbital stabilization (relativistic)
- 7p orbital destabilization  
- Electron shielding breakdown

**Chemical behavior predictions:**
- Ionization energy: ↑ (vs Cs trend)
- Reactivity: expected ↑, but Cs actually most reactive (paradox!)
- Bonding character: more covalent

### 4. Theoretical Framework

⟨H≈0.3⟩ Dirac equation becomes essential. 8s electron "feels" relativistic mass increase → tighter binding → higher IE. Counterintuitive. p-orbital electrons in 7p subshell experience relativistic expansion → larger ionic radii, weaker electronegativity.

**Key insight !** Heavier ≠ necessarily more reactive

### 5. Synthesis

**For francium itself:**
- More electrons → theoretical instability (radioactive decay)
- No stable isotopes beyond Fr-223

**For hypothetical superheavy elements (Z>119):**
- Predicted electron configurations: 9s, 10s, etc.
- Relativistic effects intensify: stronger 8s stabilization
- Result: elements behave as alkali metals but **weaker**
- Smaller atomic radii, higher IE, decreased reactivity

**Contradiction resolved:** 
Cs is actually strongest reducing agent (despite relativistic effects in Fr). Larger electron cloud = more polarizable = stronger reducing power.

∴ "Stronger" intuition incorrect for heaviest alkali metals.

### 6. Verification Against Physical Reality

● Cs reactivity data confirms theoretical predictions for Fr
● Superheavy element synthesis attempts support electronic structure models  
● Relativistic calculations reproduce observed trends for lighter heavy elements

**Conclusion:** Additional electrons in francium/superheavy alkali metals → decreased chemical activity, not increased. Relativistic effects dominate periodic trends.

### Answer###
Si l'on ajoutait des électrons au francium, les éléments ainsi formés suivraient des tendances particulières. Le francium, en tant que métal alcalin le plus lourd connu, présente déjà des propriétés qui s'écartent des tendances normales dues aux effets relativistes importants.

Pour les éléments hypothétiques plus lourds, plusieurs facteurs s'opposent. D'une part, l'orbitale 8s serait stabilisée par les effets relativistes, ce qui augmenterait leur énergie d'ionisation et diminuerait leurs rayons atomiques, les rendant moins réactifs que prévu. Paradoxalement, cela signifierait que ces éléments seraient plus faibles chimiquement que le césium, malgré leur plus grand nombre d'électrons.

D'autre part, les électrons dans les orbitales 7p seraient déstabilisés et se comporteraient de manière à former des composés avec un caractère covalent important. Les calculs prédisent que ces éléments pourraient théoriquement former des états d'oxydation supérieurs à +1, ce qui n'est pas observé chez les métaux alcalins légers.

Le résultat net serait donc une chimie intermédiaire entre celle des métaux alcalins et celle des métaux de transition, avec une réactivité potentiellement plus faible que celle du césium, bien que les effets relativistes rendent cette prédiction complexe.