Question

Write a formula for each of the following ionic salts using the Lewis symbols of the ions. (a) \(\mathrm{Na}_{2} \mathrm{O}\) (b) LiOH (c) CsF

Short answer

The Lewis symbols for the given ionic compounds are: (a) \( \mathrm{Na} \rightarrow [\mathrm{Na}]^+ \), \( \mathrm{O} \rightarrow [\mathrm{O}]^{2-} \) (b) \( \mathrm{Li} \rightarrow [\mathrm{Li}]^+\), \( \mathrm{OH} \rightarrow [\mathrm{OH}]^- \), and (c) \( \mathrm{Cs} \rightarrow [\mathrm{Cs}]^+ \), \( \mathrm{F} \rightarrow [\mathrm{F}]^- \).

Step-by-step solution

Identify Valence Electrons for (a)

Identify the valence electrons on the atoms. Sodium (Na) is a Group 1 element and has one valence electron. This can be represented as dot next to Na symbol. Oxygen (O) is a Group 6 element and has six valence electrons. These are represented as dots around O symbol.

Write Lewis Symbols for (a)

Write Lewis symbols for each element. Two Sodium (Na) ions each donate an electron to an Oxygen (O) ion to fill its valence shell, forming the ionic compound \( \mathrm{Na}_2 \mathrm{O} \). This can be represented as :\( \dot{\mathrm{O}} \): —> \( [\mathrm{O}]^{2-}\) and \(.\mathrm{Na}\) —> \( [\mathrm{Na}]^+ \).

Identify Valence Electrons for (b)

Now do the same for Lithium Hydroxide (LiOH). Lithium (Li) is a Group 1 element with one valence electron and Oxygen (O) is a Group 6 element with six valence electrons. Hydrogen (H) has one valence electron.

Write Lewis Symbols for (b)

Write Lewis symbols for each element. The Lithium (Li) ion donates an electron to the Hydroxide (OH) ion. This forms the ionic compound LiOH that can be represented as :\( \dot{\mathrm{O}} \):\(\mathrm{H}\) —> \( [\mathrm{O}\mathrm{H}]^- \) and \(.\mathrm{Li} \) —> \( [\mathrm{Li}]^+ \).

Identify Valence Electrons for (c)

Lastly, identify the valence electrons for Cesium Fluoride (CsF). Cesium (Cs) is a Group 1 element and has one valence electron. Fluorine (F) is a Group 7 element with seven valence electrons.

Write Lewis Symbols for (c)

The Cesium (Cs) ion donates an electron to the Fluorine (F) ion to complete its valence shell, forming the ionic compound CsF. This is represented as :\(\mathrm{F}\) —> \( [\mathrm{F}]^- \) and \(.\mathrm{Cs}\) —> \( [\mathrm{Cs}]^+ \).

Key concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom. They play a crucial role in chemical bonding. Atoms are more stable when they have full valence shells, similar to noble gases.

• In Group 1 elements, such as Sodium (Na) and Lithium (Li), there is just one valence electron.
• On the other hand, Oxygen (O), being part of Group 6, has six valence electrons poised to create bonds.

Understanding valence electrons helps in predicting how elements will interact to form compounds. During chemical reactions, atoms either lose, gain, or share valence electrons to achieve stability. For example, when you take Cesium (Cs) from Group 1, which has a single valence electron, it can easily donate that electron to fill the outer shell of a fluorine atom from Group 7.

Ionic Compounds

Ionic compounds are formed when atoms transfer valence electrons from one to another, establishing strong ionic bonds. This exchange typically occurs between metals and nonmetals.

• Metals, like Sodium (Na), Cesium (Cs), and Lithium (Li), tend to lose their valence electrons and become positively charged ions.
• Nonmetals, like Oxygen (O) and Fluorine (F), tend to gain these electrons, forming negatively charged ions.

The result is a compound, such as Na extsubscript{2}O, LiOH, or CsF. These compounds appear because of the electrostatic attraction between oppositely charged ions. The metal cations and nonmetal anions arrange in a lattice structure. Because of this, ionic compounds usually have high melting and boiling points and are often soluble in water.

Group Elements

Atoms are categorized into groups in the periodic table, based on their similar chemical properties and the number of valence electrons.

• Group 1 elements, like Sodium (Na), Cesium (Cs), and Lithium (Li), feature one valence electron and are known for being highly reactive.
• Group 6, which includes Oxygen (O), has six valence electrons, while Group 7, holding Fluorine (F), is recognized for its seven valence electrons.

The characteristics of these group elements define their interactions. For instance, Group 1 metals are frequently reactive because they easily lose their valence electron to achieve a stable configuration. Group elements' positions aid in predicting bonding patterns. This knowledge eases understanding of why atoms form certain chemical structures, like Na extsubscript{2}O or CsF. Thus, mastering group elements provides a foundational understanding of chemical behaviors and reactions.