Chapter 3 General Chemistry I

What is the result of elements combining to form compounds?

An entirely new substance is created.

How do mixtures differ from compounds?

In a mixture, elements can mix in any proportions, while in a compound, elements combine in fixed, definite proportions.

What is the definite proportion of hydrogen to oxygen in water?

Water is composed of two hydrogen atoms for every one oxygen atom.

What are the two broad classifications of chemical bonds?

Ionic bonds and covalent bonds.

What occurs during the formation of ionic bonds?

Electrons are transferred from a metal atom to a nonmetal atom, creating cations and anions.

What is the structure of ionic compounds in solid phase?

Ionic compounds form a lattice of alternating cations and anions.

What defines covalent bonds?

Covalent bonds occur between two or more nonmetals that share electrons.

What is the difference between empirical and molecular formulas?

An empirical formula gives the relative number of atoms, while a molecular formula gives the actual number of atoms in a molecule.

What does a structural formula represent?

A structural formula uses lines to represent covalent bonds and shows how atoms are connected in a molecule.

What is a molecular model?

A molecular model represents atoms as balls and chemical bonds as sticks, reflecting a molecule's shape.

What are atomic elements?

Atomic elements exist as single atoms as their basic units.

What are molecular elements?

Molecular elements exist as molecules, which are two or more atoms of the element bonded together.

What is the basic unit of an ionic compound?

The formula unit, which is the smallest, electrically neutral collection of ions.

What is the composition of molecular compounds?

Molecular compounds are usually composed of two or more covalently bonded nonmetals.

What is the difference between ionic and molecular compounds?

Ionic compounds contain nondirectional ionic bonds forming ionic lattices, while molecular compounds contain highly directional covalent bonds forming molecules.

What is the basic unit of a molecular compound?

The molecule composed of the constituent atoms.

What is the significance of chemical formulas?

Chemical formulas indicate the elements present in a compound and the relative number of atoms or ions of each.

How are molecular models useful?

They provide a more accurate and complete representation of a compound's structure.

What type of bond forms between nitrogen and oxygen?

Covalent bond.

What is the role of chemical bonds in compounds?

They hold atoms together through attractions between charged particles.

What is an example of a molecular compound?

Water (H₂O) is a molecular compound made of covalently bonded hydrogen and oxygen.

What is the composition of sodium chloride?

Sodium chloride (NaCl) is composed of sodium cations and chloride anions.

What is the empirical formula for water?

The empirical formula for water is HO.

What do space-filling models represent?

They represent how atoms fill the space between each other in a molecule.

What is a characteristic of ionic compounds?

They are composed of cations and anions bound together by ionic bonds.

What is the formula unit for table salt?

NaCl, which consists of ions in a one-to-one ratio.

What must be true about the charges in an ionic compound?

The sum of the charges of the cations must equal the sum of the charges of the anions.

How can the charges of representative elements be predicted?

From their group numbers; they form only one type of charge.

What type of metals tend to form multiple types of charges?

Transition metals.

What are Type One ionic compounds?

Ionic compounds that contain a metal with a charge that is invariant across compounds.

Give an example of a Type One binary ionic compound.

KCl, which is named potassium chloride.

What distinguishes Type Two ionic compounds?

They contain a metal that can form more than one kind of cation.

How is the charge of a metal cation in Type Two compounds indicated?

By a Roman numeral in parentheses following the name of the cation.

What are polyatomic ions?

Ions composed of a group of covalently bonded atoms with an overall charge.

How are ionic compounds containing polyatomic ions named?

By using the name of the polyatomic ion whenever it occurs.

What are oxyanions?

Polyatomic ions that contain oxygen and another element.

What is the naming convention for oxyanions with different numbers of oxygen atoms?

The one with more oxygen atoms ends in -ate, and the one with fewer ends in -ite.

What are hydrates?

Ionic compounds containing a specific number of water molecules associated with each formula unit.

What is the systematic name for MgSO4·7H2O?

Magnesium sulfate heptahydrate.

How do molecular compounds differ from ionic compounds?

Molecular compounds are composed of two or more nonmetals and do not have a straightforward formula from their constituent elements.

What prefixes are used in naming binary molecular compounds?

Mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-.

When is the prefix mono- omitted in molecular compound names?

When there is only one atom of the first element in the formula.

What defines an acid in chemistry?

A molecular compound that releases hydrogen ions when dissolved in water.

What is the general formula structure for acids?

Acids generally start with H, e.g., HCl.

What are binary acids composed of?

Hydrogen and a nonmetal.

What is the charge of the iron cation in FeS?

+2 charge.

What is the charge of the chromium cation in CrBr3?

+3 charge.

What is the naming convention for ionic compounds with metals that form more than one cation?

The name of the cation is followed by a Roman numeral indicating its charge.

What is the systematic name for CuO?

Copper(II) oxide.

What is the name for NaNO2?

Sodium nitrite.

What is the difference in naming between ionic and molecular compounds?

Ionic compounds do not use prefixes like mono-, di-, and tri-, while molecular compounds do.

What are acids composed of?

Hydrogen and one or more nonmetals.

What is the typical taste of acids?

Sour taste.

Which metals do acids dissolve?

Zinc (Zn), Iron (Fe), and Magnesium (Mg); but not Gold (Au), Silver (Ag), or Platinum (Pt).

What is the general formula structure of acids?

Formulas generally start with H, e.g., HCl.

What happens when HCl is dissolved in water?

It forms ions, where aqueous (aq) means dissolved in water.

What are oxyacids composed of?

Hydrogen and an oxyanion.

How do you name binary acids?

Write a hydro- prefix, followed by the nonmetal base name, add -ic, and write 'acid' at the end.

How do you name oxyacids when the polyatomic ion ends in -ate?

Change the ending to -ic and write 'acid' at the end.

How do you name oxyacids when the polyatomic ion ends in -ite?

Change the ending to -ous and write 'acid' at the end.

What is acid rain?

Rainwater that becomes acidic due to pollutants forming acids when mixed with water.

What is formula mass?

The mass of an individual molecule or formula unit, also known as molecular mass or molecular weight.

What is the molar mass of a compound?

The mass, in grams, of 1 mole of its molecules or formula units.

How can molar mass be used to count molecules?

By using it in combination with Avogadro's number to determine the number of atoms in a given mass.

What is an empirical formula?

The simplest, whole-number ratio of the atoms or moles of elements in a compound.

How do you find an empirical formula?

Convert percentages to grams, then to moles, and write a pseudoformula using calculated moles as subscripts.

What is a molecular formula?

A whole-number multiple of the empirical formula.

What is combustion analysis?

A technique for analyzing compounds by burning a known mass and weighing the products.

What distinguishes organic compounds from inorganic compounds?

Organic compounds originate from living things and contain mainly carbon and hydrogen.

What are hydrocarbons?

Organic compounds that contain only carbon and hydrogen.

What are the three types of hydrocarbons based on bonding?

Alkanes (single bonds), Alkenes (double bonds), Alkynes (triple bonds).

What is a functional group?

An atom or group of atoms that imparts specific chemical properties to an organic compound.

What is the significance of carbon in organic chemistry?

Carbon is the key element, capable of forming four covalent bonds and limitless chains.

What is the base name for a 5-carbon alkane?

Pent-.

What does the 'n' in normal hydrocarbons signify?

It indicates a straight-chain structure.

What is the mass percent composition used for?

To show the mass ratio of an element in a compound, which can be used as a conversion factor.

What is the relationship between empirical and molecular formulas?

The molecular formula is a whole-number multiple of the empirical formula.

How can you determine the mass percentage of each element in a compound?

From the formula of the compound and experimental mass analysis.