Question

Write the formulas for the following compounds, and indicate the oxidation state of the group \(4 \hat{A}\) element or of boron in each: (a) silicon dioxide, (b) germanium tetrachloride, (c) sodium borohydride, (d) stannous chloride, (e) diborane.

Short answer

The chemical formulas and oxidation states for the given compounds are as follows: (a) Silicon dioxide: SiO₂, silicon has an oxidation state of +4. (b) Germanium tetrachloride: GeCl₄, germanium has an oxidation state of +4. (c) Sodium borohydride: NaBH₄, boron has an oxidation state of +3. (d) Stannous chloride: SnCl₂, tin has an oxidation state of +2. (e) Diborane: B₂H₆, boron has an oxidation state of +3.

Step-by-step solution

Identify the elements in the compound

Silicon (Si) and oxygen (O) are the elements present in the compound.

Write down the chemical formula

Since silicon has a +4 charge and oxygen has a -2 charge, both elements will balance each other out. Therefore, the chemical formula for silicon dioxide is SiO₂.

Identify oxidation state

The oxidation state of silicon in this compound is +4. For (b) Germanium tetrachloride:

Identify the elements in the compound

Germanium (Ge) and chlorine (Cl) are the elements present in the compound.

Write down the chemical formula

Since germanium has a +4 charge and chlorine has a -1 charge, four chlorine atoms are required to balance the charge. Therefore, the chemical formula for germanium tetrachloride is GeCl₄.

Identify oxidation state

The oxidation state of germanium in this compound is +4. For (c) Sodium borohydride:

Identify the elements in the compound

Sodium (Na), boron (B), and hydrogen (H) are the elements present in the compound.

Write down the chemical formula

Since sodium has a +1 charge, boron has a +3 charge, and hydrogen has a -1 charge, the compound would be balanced with one sodium atom, one boron atom, and four hydrogen atoms. Therefore, the chemical formula for sodium borohydride is NaBH₄.

Identify oxidation state

The oxidation state of boron in this compound is +3. For (d) Stannous chloride:

Identify the elements in the compound

Tin (Sn) and chlorine (Cl) are the elements present in the compound.

Write down the chemical formula

Since stannous refers to tin with a +2 oxidation state and chlorine has a -1 charge, two chlorine atoms are required to balance the charge. Therefore, the chemical formula for stannous chloride is SnCl₂.

Identify oxidation state

The oxidation state of tin in this compound is +2. For (e) Diborane:

Identify the elements in the compound

Boron (B) and hydrogen (H) are the elements present in the compound.

Write down the chemical formula

The prefix "di" indicates two boron atoms, and based on the empirical formula, there are 6 hydrogen atoms. Therefore, the chemical formula for diborane is B₂H₆.

Identify oxidation state

Since the compound consists of two boron atoms with a +3 charge and six hydrogen atoms with a -1 charge, the overall oxidation state of boron in diborane is +3.

Key concepts

Chemical Nomenclature

Chemical nomenclature is the systematic way of naming chemical compounds based on their composition and structure, following rules established by the International Union of Pure and Applied Chemistry (IUPAC). This system allows chemists to convey information about the elements within a compound and the proportions in which they combine. For example, the compound SiO₂ is named silicon dioxide because it consists of silicon (Si) and oxygen (O), with the 'di-' prefix indicating two oxygen atoms are bound to one silicon atom. Learning chemical nomenclature is essential for students as it provides a universal language of chemistry that is recognized worldwide.

Inorganic compounds, such as stannous chloride (SnCl₂), have names derived from the charge of the ions. The term 'stannous' indicates the +2 oxidation state of tin (Sn), while 'chloride' comes from chlorine (Cl), whose ionic form has a -1 charge. Nomenclature becomes especially critical when distinguishing compounds with the same elements but different proportions, such as the difference between stannous chloride (tin(II) chloride) and stannic chloride (tin(IV) chloride), which has not been covered in the exercise.

Oxidation-Reduction Chemistry

Oxidation-reduction (redox) chemistry involves reactions where electrons are transferred between molecules, altering their oxidation states. These processes are fundamental to many chemical reactions, including those that power batteries and sustain life through cellular respiration. The oxidation state, often called oxidation number, helps chemists understand how electrons are distributed in a molecule and which atoms have gained or lost electrons during the reaction.

An example from the textbook exercise is sodium borohydride (NaBH₄), where boron has an oxidation state of +3. In the framework of redox chemistry, this represents boron's capacity to accept electrons. Recognizing this concept is vital for students as it assists in predicting the outcomes of chemical reactions and explains the reactivity of different substances.

Stoichiometry

Stoichiometry is the quantitative aspect of chemical formulas and reactions. It deals with the calculation of the reactants and products in chemical reactions. Stoichiometry is founded on the law of conservation of mass, where the quantity of each element is conserved in a chemical reaction. The calculations rely heavily on the mole concept, which links the mass of a substance to the number of particles it contains.

Applying stoichiometry, students can determine the proportions of elements that combine to form a compound, such as the one-to-two ratio of tin to chlorine atoms in stannous chloride (SnCl₂). Moreover, exercising stoichiometric principles enables the prediction of the amount of product formed from given reactants or the necessary quantities of reactants to produce a desired amount of product, skills which have not been explicitly called upon in the provided exercise but remain crucial to the understanding of chemistry.

Inorganic Compounds

Inorganic compounds comprise a diverse range of substances that are not based on carbon-hydrogen bonds, differing from organic compounds. Common categories include salts, oxides, acids, bases, and various coordination compounds. Inorganic chemistry is concerned with the properties and behaviors of these substances, often involving metals and other elements from different areas of the periodic table.

The textbook exercise introduces several inorganic compounds, such as diborane (B₂H₆) and silicon dioxide (SiO₂). It is crucial for students to grasp that despite the lack of carbon, inorganic compounds can have complex structures and varied reactivities. For instance, diborane's structure presents unique bonding that doesn't conform to simple rules, showcasing the diversity of inorganic chemistry.