Problem 107 - Introductory Chemistry Atoms First

Question

What is the most electronegative element in the periodic table? What is the least electronegative element? What kind of compound would form if these two elements were brought together?

Step-by-Step Solution

Answer

The most electronegative element in the periodic table is Fluorine (F) with an electronegativity value of 3.98, while the least electronegative element is Francium (Fr) with an electronegativity value of 0.7. When these two elements are brought together, they form an ionic compound called Francium fluoride (FrF), where Fluorine gains an electron (F-) and Francium loses an electron (Fr+).

Step 1: Identify the most electronegative element

The most electronegative element can be found in the upper right corner of the periodic table, excluding the noble gases. This element is Fluorine (F) with an electronegativity value of 3.98 on the Pauling scale.

Step 2: Identify the least electronegative element

The least electronegative element can be found in the lower left corner of the periodic table. This element is Francium (Fr) with an electronegativity value of 0.7 on the Pauling scale.

Step 3: Determine the type of compound that would form between these two elements

Fluorine, being highly electronegative, will attract electrons and develop a negative charge. Francium, being least electronegative, will lose electrons and develop a positive charge. When these two elements are brought together, they will form an ionic compound with Fluorine gaining an electron (F-) and Francium losing an electron (Fr+). The compound formed is Francium fluoride (FrF).

Key Concepts

The Periodic Table

The periodic table is a systematic way to organize all known elements. It is arranged by increasing atomic number, and elements are positioned according to similar properties.
One of the most important patterns observed is electronegativity, which is the tendency of an atom to attract electrons towards itself.

• Electronegativity generally increases as you move from left to right across a period.
• It generally decreases as you move down a group.

Fluorine, located in the upper right corner, is the most electronegative element. In contrast, elements on the lower left, such as Francium, have the lowest electronegativity. Understanding this arrangement can help predict how different elements might interact to form compounds.

Ionic Compound

Ionic compounds are formed when atoms transfer electrons between each other. The difference in electronegativity between the two interacting elements usually dictates this process.
Fluorine, with a high electronegativity, tends to attract electrons, forming a negative ion (anion). Francium, on the other hand, loses electrons due to its low electronegativity, forming a positive ion (cation).

• This electron transfer creates a strong electrostatic attraction.
• The resulting substance is an ionic compound, such as Francium fluoride (FrF).

Ionic compounds are characterized by high melting and boiling points and can conduct electricity when dissolved in water or melted.

Fluorine

Fluorine is often referred to as the most electronegative element on the periodic table. This high electronegativity means that it has a strong ability to attract electrons.
Due to its reactivity, Fluorine can form bonds with many elements, which results in a wide range of compounds.

• In the periodic table, Fluorine is situated in Group 17, which is the halogens group.
• Fluorine's high electronegativity makes it a powerful oxidizing agent.

Understanding Fluorine’s properties is crucial in predicting its behavior with other elements, particularly when forming ionic compounds.

Francium

Francium is known for being one of the least electronegative elements. This means it doesn't attract electrons strongly.
Located in the alkali metals group, it is highly reactive, especially with electronegative elements like Fluorine.

• Francium is positioned at the far bottom left of the periodic table.
• It rarely exists in nature due to its instability and high reactivity.

Due to its properties, Francium easily gives up its electrons, which results in the formation of ionic compounds when combined with more electronegative elements.