Question

Apply Sodium forms a \(1+\) ion, while fluorine forms a \(1-\) ion. Write the electron configuration for each ion. Why don't these two elements form \(2+\) and \(2-\) ions, respectively?

Short answer

The electron configuration for sodium ion (Na⁺) is 1s²2s²2p⁶, and for the fluorine ion (F⁻), it is 1s²2s²2p⁶. Both ions achieve the stable noble gas configuration of neon. Sodium doesn't form a 2+ ion because it would require a significantly higher amount of energy to remove an electron from an inner shell, making it energetically unfavorable. Fluorine doesn't form a 2- ion because adding a second extra electron would make the ion much larger and less stable, as the extra electron experiences weaker attraction to the nucleus due to increased electron-nucleus distance.

Step-by-step solution

Write the electron configuration for Sodium atom (Na)

To determine the electron configuration for sodium atom (Na), we need to look at its atomic number in the periodic table. Sodium has an atomic number of 11, which means it has 11 electrons in its ground state. The electron configuration for sodium is 1s²2s²2p⁶3s¹.

Write the electron configuration for Sodium ion (Na⁺)

To form a stable 1+ ion, sodium loses one electron from its outermost 3s orbital. Thus, the electron configuration for sodium ion (Na⁺) will be 1s²2s²2p⁶, which is the same as the noble gas neon (Ne).

Write the electron configuration for Fluorine atom (F)

Next, let's identify the electron configuration for fluorine atom (F), which has an atomic number of 9. The electron configuration for fluorine is 1s²2s²2p⁵.

Write the electron configuration for Fluorine ion (F⁻)

Fluorine forms a stable 1- ion by gaining one electron in its outermost 2p orbital. The electron configuration for fluorine ion (F⁻) will be 1s²2s²2p⁶, which is the same as the noble gas configuration for neon (Ne). Now let's address why sodium and fluorine do not form 2+ and 2- ions respectively.

Explain why Sodium doesn't form a 2+ ion

If sodium were to lose two electrons and form a 2+ ion, it would require removing an electron from the 2p orbital (1s²2s²2p⁴). This process would need a significantly higher amount of energy to remove an electron from an inner shell, making it energetically unfavorable. Forming a Na⁺ ion is more stable, as it acquires the noble gas configuration of neon, which results in lower energy and more stability.

Explain why Fluorine doesn't form a 2- ion

For fluorine to form a 2- ion, it would need to gain two electrons. Since the outermost shell can only accommodate a maximum of 8 electrons, adding a second extra electron would require fluorine to start filling its next shell with a capacity of 18 electrons (3s²3p⁶3d¹⁰). However, this would make the ion much larger and less stable, as the extra electron would experience weaker attraction to the positively charged nucleus due to the increased distance between the electron and the nucleus. Therefore, gaining just one electron and forming an F⁻ ion with the noble gas configuration of neon is energetically most favorable for fluorine.

Key concepts

Ionic Bonding

Ionic bonding represents one of the most fundamental interactions in chemistry, playing a vital role in the structure and properties of many compounds. It occurs when atoms with opposite charges attract each other to form a stable compound. This attraction is due to the transfer of electrons from one atom to another, leading to the formation of ions. The example of sodium (Na) and fluorine (F) illustrates ionic bonding beautifully. Sodium, a metal, tends to lose an electron to achieve stability, forming a Na⁺ ion with a positive charge. Fluorine, a non-metal, accepts an electron, becoming a F⁻ ion with a negative charge. These ions, with opposite charges, are drawn to each other, resulting in an ionic bond.

Understanding why sodium forms a 1+ ion instead of a 2+ ion highlights the concept of energy efficiency in ionic bonding. For an atom like sodium, removing one electron to match the electron configuration of a noble gas is relatively easy and energetically cheaper. Removing a second electron would mean breaking into a lower energy level, which is highly unfavorable due to the increased energy requirement. Similarly, for fluorine to accept an additional electron and become a 2- ion would defy the rules of maximum stability and efficiency, as the added electron would be forced into a new, energetically unsuitable energy level. Consequently, we observe the formation of Na⁺ and F⁻ ions that happily engage in ionic bonding, each achieving a noble gas configuration and the most energetically favorable state.

Periodic Table

The periodic table is not just a chart; it's a comprehensive map of the elements, guiding us through their properties and the relationships between them. By understanding the periodic table, one can predict how elements are likely to behave and interact with each other. Each element is positioned based on its atomic number – the number of protons in its nucleus – and grouped with others that have similar chemical properties. Elements in the same column, or group, typically have similar electron configurations, especially in their outer shells.

For instance, sodium (Na) and fluorine (F) are positioned in the periodic table such that their electron configurations can be predicted: sodium, found in group 1, has one valence electron, while fluorine, located in group 17, has seven valence electrons. The periodic table foretells that sodium is likely to lose its lone outer electron and fluorine is eager to gain one more, aligning each with the coveted stable electron configuration of the nearest noble gas. It's the orderly pattern of the periodic table that clues us into the likelihood of elements forming certain ions, based on the ease with which they can achieve noble gas configuration by losing or gaining electrons.

Atomic Structure

Delving into atomic structure unveils the intricate design of matter at its most basic level. Each atom is composed of a nucleus, which houses protons and neutrons, orbited by a cloud of electrons. The electrons are arranged in energy levels or shells that are progressively further from the nucleus. The outermost shell is crucial because it dictates an atom's chemical behavior, including its ability to bond with other atoms.

The behavior of sodium (Na) and fluorine (F) is a classic demonstration of atomic structure in action. When we consider sodium's structure, it has just one valence electron in its most external shell. This lone electron is relatively easy to remove, as it feels only a weak attraction to the positively charged nucleus. Fluorine, on the other hand, has seven valence electrons and just needs one more to complete its outer shell. The concept of atomic structure explains the tendencies of electrons to either stay with an atom or leave; it's not just about filling or emptying the outer shell, but doing so in a way that uses energy resources efficiently and achieves a state of maximum possible stability – usually the noble gas electron configuration.