Question

According to valence bond theory, how many bonds would you expect each of the following atoms (in the ground state) to form: \(\mathrm{P}, \mathrm{S} ?\)

Short answer

Phosphorus forms 3 bonds; sulfur forms 2 bonds.

Step-by-step solution

Determine Valence Electrons for Phosphorus

Phosphorus (P) is in group 15 of the periodic table, which means it has 5 valence electrons. Valence electrons for an atom are critical in predicting its bonding behavior because these are the electrons involved in bond formation.

Predict Bonds for Phosphorus

According to valence bond theory, an atom tends to form as many bonds as it has unpaired electrons in its ground state. Phosphorus has 3 unpaired electrons, so it typically forms 3 bonds.

Determine Valence Electrons for Sulfur

Sulfur (S) is in group 16 of the periodic table, meaning it has 6 valence electrons. This influences how many bonds the sulfur atom can form in its ground state.

Predict Bonds for Sulfur

In its ground state, sulfur has 2 unpaired electrons because it needs two more electrons to complete its octet. Therefore, sulfur typically forms 2 bonds.

Key concepts

Phosphorus Bonding

Phosphorus is a fascinating element when it comes to bonding. Positioned in group 15 of the periodic table, phosphorus has a total of five valence electrons. Valence electrons are vital in determining how an atom bonds with others. Think of these electrons as the outer line of dancers in a circle, ready to join hands with those from another circle. In the case of phosphorus, it uses these electrons to form bonds, generally with three other atoms. This is because among the five valence electrons, three are unpaired, and these unpaired electrons are available to form covalent bonds. When forming simple compounds, phosphorus typically creates three bonds, such as in phosphine (PH₃) or other phosphorus-containing molecules.

Sulfur Bonding

Sulfur, another essential element, is known for its versatility in bonding. Positioned in group 16 of the periodic table, it has six valence electrons. These electrons play a critical role in its bonding behavior. In the ground state, sulfur has two unpaired electrons. These are the electrons that can form bonds according to valence bond theory. Sulfur can typically make two bonds as seen in simple molecules like hydrogen sulfide (H₂S). However, sulfur's capacity for more exotic bonding patterns allows it to create compounds like sulfur hexafluoride (SF₆), where it forms six bonds. This is because sulfur can extend its usual coordination number by using d-orbitals to facilitate more bonding.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial for chemical bond formation. They are located in the shell furthest from the nucleus and help an atom bond with others by either sharing or transferring to achieve stable electronic configuration. Typically, atoms aim to complete their outer shell to become like noble gases, which is often eight electrons for most atoms. This concept is known as the octet rule. The number of valence electrons determines how many bonds an atom can form.

• Atoms in group 15, like phosphorus, have 5 valence electrons and typically form three bonds.
• Atoms in group 16, like sulfur, have 6 valence electrons and typically form two bonds.

This knowledge helps predict how atoms will interact in molecular compounds.

Periodic Table Groups

The periodic table groups elements in columns that share similar chemical properties due to their valence electron configurations. Each group consists of elements with the same number of valence electrons, influencing their bonding abilities. For example, group 15 elements like nitrogen and phosphorus generally form three bonds, while group 16 elements like oxygen and sulfur usually form two bonds. This systematic arrangement allows predictions not only about number of bonds an element can form but also about general chemical reactivity.

• Group 15 elements have a form of electron configuration that facilitates forming three bonds.
• Group 16 elements, with an almost complete octet, generally form two bonds.

Understanding the periodic table groups is key to mastering concepts like valence bond theory.