Question

Write the electron dot formula and draw the structural formula for stibine, \(\mathrm{SbH}_{3}\), whose central atom is a semimetal.

Short answer

\(\mathrm{SbH}_{3}\) has an electron dot formula showing 3 bonds and a lone pair on Sb; its structural formula depicts three Sb-H bonds.

Step-by-step solution

Count Total Valence Electrons

First, we need to count the total number of valence electrons in the \(\mathrm{SbH}_3\) molecule. Antimony (Sb) belongs to group 15 of the periodic table and has 5 valence electrons. Each hydrogen (H) atom has 1 valence electron and there are three hydrogen atoms. Hence, the total number of valence electrons = 5 (from Sb) + 3 (1 from each H) = 8 electrons.

Distribute Electrons Around the Atom

Sb is the central atom and we will place the three hydrogen atoms around it. Initially, we pair the electrons to form bonds between Sb and the three H atoms: - Each Sb-H bond uses 2 electrons. - 3 bonds mean 3 pairs of electrons = 6 electrons. - Hence, 6 of the 8 electrons are used to form these bonds.

Place Remaining Electrons on Central Atom

After forming all Sb–H bonds, 2 electrons remain (8 total - 6 used = 2 remaining). These remaining electrons will be placed as a lone pair on the Sb atom. Now, Sb has a complete octet with 6 electrons in bonds and 2 electrons as a lone pair.

Draw the Electron Dot Formula

In the electron dot structure of \(\mathrm{SbH}_{3}\), represent the bonds between antimony and hydrogen using dots and show the lone pair on Sb:\[ \cdot \cdot \mathrm{H: Sb :H} \cdot \cdot \]\[ \hspace{1cm} \ |\] \[ \hspace{1cm} \mathrm{H}\]This structure shows each bonding pair as a set of 2 dots and the lone pair as two dots adjacent to \(\mathrm{Sb}\).

Draw the Structural Formula

In the structural formula, lines represent bonds between atoms. Each line represents a pair of bonding electrons, so there will be one line for each Sb-H bond and no need to show lone pairs. Thus, the structure will be drawn as:\[\begin{align*}&\mathrm{H} \& \ | \& \mathrm{Sb} - \mathrm{H} \& \ /\end{align*}\]Indicating bonds from Sb to each H atom.

Key concepts

Valence Electrons

In chemistry, valence electrons play a crucial role in the formation of chemical bonds. These are the outermost electrons of an atom that are available for forming bonds with other atoms.
In terms of electron dot formulas, these valence electrons are specifically illustrated to highlight bonding possibilities.
To determine the number of valence electrons, you'll often look at the group number of the element within the periodic table. For example, antimony (Sb), located in group 15, has five valence electrons. This means it can form bonds using these five outer electrons.

• In the context of molecules, like \( \mathrm{SbH}_3 \), each hydrogen brings one valence electron to the table.
• Combining antimony’s five valence electrons with the three from hydrogen results in a total of eight valence electrons for the molecule.

Understanding the distribution of these electrons between different atoms helps explain the molecule's stability and geometry.

Semimetals

Semimetals or metalloids display properties characteristic of both metals and non-metals, often referred to as elements like antimony (Sb).
They are fascinating due to their ability to form complex bonding and electron structures.
A characteristic feature of semimetals is their ability to have variable oxidation states and form covalent bonds. This provides flexibility in forming different chemical compounds.
Antimony, as a semimetal, forms the central hub in \( \mathrm{SbH}_3 \),allowing for the distribution of valence electrons such that stable bonds with hydrogen are achieved, while also supporting lone pairs that influence the molecule's shape.

• Semimetals like Sb often have mixed ionic and covalent bonding characteristics.
• These elements can bridge the gap between metallic and non-metallic behavior in chemistry.

This unique behavior underscores why semimetals are studied both for their intrinsic properties and their role in compounds.

Lewis Structures

Lewis structures are a visual representation of the bonds and valence electrons within a molecule. They are a fundamental tool in chemistry, helping to predict the shape, behavior, and reactivity of molecules.

When drawing a Lewis structure for \( \mathrm{SbH}_3 \), the process begins by identifying the total number of valence electrons, which is eight in this case. Next, electrons are arranged to satisfy the bonding needs of each atom.

• Each line representing a bond indicates a pair of shared electrons between atoms.
• Lone pairs are depicted as extra pairs of dots around central atoms like Sb, which do not participate in bonding.

The placement of these electrons, particularly lone pairs, influences molecular geometry.In \( \mathrm{SbH}_3 \),Sb organizes its electrons to form three bonds with hydrogen while one lone pair remains unbonded, leading to a pyramidal shape as predicted by VSEPR theory.
Understanding this arrangement helps in predicting physical and chemical properties.