Question

Write formulas for the following. (a) mercury(II) acetate (b) barium hydrogen sulfite (c) boron trichloride (d) calcium phosphide (e) magnesium dihydrogen phosphate (f) calcium oxalate (g) xenon tetrafluoride

Short answer

The chemical formulas are (a) Hg(CH3COO)2, (b) Ba(HSO3)2, (c) BCl3, (d) Ca3P2, (e) Mg(H2PO4)2, (f) CaC2O4, and (g) XeF4.

Step-by-step solution

Determine the Charge of Mercury(II)

Determine the charge of mercury in mercury(II) acetate. The (II) indicates that mercury has a charge of +2.

Write the Formula for Mercury(II) Acetate

Using the charge of mercury, write the formula knowing that the acetate ion has a charge of -1. Since the charges must balance, two acetate ions will be needed for every mercury ion. The formula is Hg(CH3COO)2.

Identify the Barium and Hydrogen Sulfite Ions

Barium has a charge of +2, and hydrogen sulfite has a charge of -1. The formula for hydrogen sulfite is HSO3.

Write the Formula for Barium Hydrogen Sulfite

Two hydrogen sulfite ions are needed to balance the charge of one barium ion. The formula is Ba(HSO3)2.

Determine the Charge of Boron Trichloride

In boron trichloride, boron is a neutral atom and chlorine is a neutral atom as it is a diatomic molecule. Simply combine one boron atom with three chlorine atoms to make BCl3.

Write the Formula for Calcium Phosphide

Calcium has a charge of +2, and the phosphide ion has a charge of -3. Use the criss-cross method to balance the charges. The resulting formula is Ca3P2.

Identify the Magnesium and Dihydrogen Phosphate Ions

Magnesium has a charge of +2, and dihydrogen phosphate has a charge of -1. The formula for dihydrogen phosphate is H2PO4.

Write the Formula for Magnesium Dihydrogen Phosphate

Since magnesium has a +2 charge and each dihydrogen phosphate has a -1 charge, we need two dihydrogen phosphate ions to balance one magnesium ion. The formula is Mg(H2PO4)2.

Write the Formula for Calcium Oxalate

Calcium has a +2 charge and oxalate has a -2 charge. The chemical formula for oxalate is C2O4. Thus, only one of each is needed to balance the charges. The formula is CaC2O4.

Write the Formula for Xenon Tetrafluoride

Xenon in Xenon tetrafluoride is a noble gas and typically forms compounds where it is neutral. Fluorine has a -1 charge. The formula for xenon tetrafluoride, where four fluorine atoms bond with one xenon atom, is XeF4.

Key concepts

Chemical Nomenclature

Understanding chemical nomenclature, the system used to name chemical substances, is crucial for students tackling chemistry. It allows chemists to communicate consistently about chemical molecules and compounds. The rules for naming chemicals are standardized by international organizations like the International Union of Pure and Applied Chemistry (IUPAC).

For example, in mercury(II) acetate, 'mercury(II)' refers to the mercury ion having a +2 charge, while 'acetate' is the name of the anion (CH\(_3\)COO)\(^-\) with a -1 charge. In barium hydrogen sulfite, 'barium' represents the Ba\(^{2+}\) ion, and 'hydrogen sulfite' is the anion HSO\(_3^-\) with a -1 charge. This system helps in predicting the compounds' structures and properties based on their names.

Namaing ionic and molecular compounds follows different sets of rules. Ionic compounds, comprising metal and nonmetal ions, use a straightforward naming approach based on the ions' names and charges. Molecular compounds, consisting of nonmetals, often use prefixes to indicate the number of atoms, with examples including 'dihydrogen' for H\(_2\) or 'tetrafluoride' for F\(_4\). By mastering chemical nomenclature, students can easily write and interpret chemical formulas.

Ionic Compounds

Ionic compounds are formed from the electrostatic attractions between ions, which are charged particles. Metals typically lose electrons to become positively charged cations while nonmetals gain electrons to become negatively charged anions. When writing the formulas for ionic compounds, such as calcium phosphide or calcium oxalate, one must consider the charges of the ions involved to ensure that the compound is electrically neutral.

For instance, calcium has a +2 charge; it becomes Ca\(^{2+}\). Oxalate is an anion with a -2 charge, represented as C\(_2\)O\(_4^{2-}\). When they combine to form calcium oxalate, the charges balance out and the formula is CaC\(_2\)O\(_4\). Similarly, in calcium phosphide, Ca\(^{2+}\) and the phosphide ion P\(^{3-}\) require a 3:2 ratio to balance the charges, resulting in the formula Ca\(_3\)P\(_2\).

The understanding of charge balance is essential because it dictates the stoichiometry of the resulting compound, which is fundamental in predicting the outcomes of chemical reactions.

Molecular Compounds

Molecular compounds are composed of nonmetal atoms bonded covalently, meaning electrons are shared between atoms to fulfill the octet rule. Unlike ionic compounds, molecular compounds are named with numerical prefixes to represent the number of atoms of each element within the compound, and the 'ide' suffix is attached to the second element.

For example, boron trichloride is made up of one boron atom and three chlorine atoms, hence the prefix 'tri-' indicating three chlorine atoms. The molecular formula for boron trichloride is BCl\(_3\). Xenon tetrafluoride, another molecular compound, consists of one xenon atom and four fluorine atoms, with 'tetra-' denoting four. The formula is XeF\(_4\).

Unlike ionic compounds, molecular compounds like BCl\(_3\) and XeF\(_4\) do not divide into ions, but their systematic nomenclature provides insight into their structure, helping to predict their physical properties and chemical behavior.