[ CHEM1010 ] 4 - Molecules and Compounds

A substance composed of two or more elements combined in a fixed ratio.

What is the definition of a chemical compound?

A covalent or molecular compound.

What type of compound is composed entirely of nonmetals?

Two hydrogen atoms to one oxygen atom.

According to the Law of Definite Proportion, what is the fixed atomic ratio of hydrogen to oxygen in water?

A metal and a nonmetal.

Which two broad classes of elements typically combine to form an ionic compound?

The complete transfer of electrons from a metal atom to a nonmetal atom.

What fundamental mechanism characterizes the formation of an ionic bond?

Electrostatic forces

What specific force holds oppositely charged ions together in an ionic bond?

A crystalline lattice.

What is the characteristic three-dimensional arrangement of ions in a solid ionic compound called?

The sharing of electrons between two or more nonmetals.

What interaction defines a covalent bond?

Covalent bond

What type of chemical bond forms between nitrogen and oxygen?

To indicate the elements present and the relative number of atoms or ions of each.

What is the purpose of a compound's chemical formula?

Empirical Formula

A formula showing the simplest whole-number ratio of atoms in a compound.

Molecular Formula

A formula showing the actual number of atoms of each element in a molecule of a compound.

Structural Formula

A representation that uses lines to show how atoms in a molecule are connected.

HO

What is the empirical formula of hydrogen peroxide, H2​O2​?

Structural formula

Which type of chemical formula communicates the most information about a molecule's layout?

Empirical formula

Which type of chemical formula communicates the least information about a molecule?

Molecular compounds have highly directional bonds, while ionic compounds have nondirectional bonds.

What is the primary difference between the bonds in molecular compounds and those in ionic compounds regarding directionality?

Water is a liquid, while hydrogen and oxygen are both gases.

How does the state at room temperature of water (H2​O) compare to its constituent elements hydrogen and oxygen?

Water is used to extinguish flames, whereas hydrogen is explosive and oxygen is necessary for combustion.

How does the flammability of water differ from that of its constituent elements hydrogen and oxygen?

The cation.

In the nomenclature of binary ionic compounds, which species is named first?

−ide

What suffix is added to the end of a nonmetal anion's name in a binary ionic compound?

Potassium chloride

What is the systematic name for the ionic compound KCl?

Aluminum phosphide

What is the systematic name for the ionic compound AlP?

Ag2​O

What is the chemical formula for silver oxide?

When the metal can form more than one type of charge, such as transition metals.

Under what condition must a Roman numeral be included in the name of an ionic compound's cation?

Copper(II) chloride

What is the systematic name for CuCl2​?

Lead(IV) oxide

What is the systematic name for PbO2​?

Chromium(III) bromide

What is the systematic name for CrBr3​?

Polyatomic Ion

A group of covalently bonded atoms that carries an overall electrical charge.

What is the chemical formula for the nitrate ion?

What is the chemical formula for the sulfate ion?

Calcium carbonate

What is the systematic name for the ionic compound CaCO3​?

What is the chemical formula for the chlorite ion?

What is the chemical formula for the perchlorate ion?

What is the chemical formula for the hypochlorite ion?

Potassium thiocyanate

What is the systematic name for the ionic compound KSCN?

What is the chemical formula for barium hydroxide?

Ammonium sulfide

What is the systematic name for (NH4​)2​S?

Lithium dichromate

What is the systematic name for Li2​Cr2​O7​?

Hydrated Ionic Compound

An ionic compound that contains a specific number of water molecules associated with each formula unit.

hepta−

What prefix is used in hydrate nomenclature to indicate seven water molecules?

hemi−

What prefix is used in hydrate nomenclature to indicate half a water molecule?

Magnesium sulfate heptahydrate

What is the systematic name for MgSO4​⋅7H2​O?

Cobalt(II) chloride hexahydrate

What is the systematic name for CoCl2​⋅6H2​O?

Na2​CO3​⋅10H2​O

What is the chemical formula for sodium carbonate decahydrate?

FePO4​⋅4H2​O

What is the chemical formula for iron(III) phosphate tetrahydrate?

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

In the nomenclature of molecular compounds, when is the prefix mono− normally omitted?

penta−

What is the prefix used for five atoms in molecular compound nomenclature?

Carbon tetrachloride

What is the systematic name for CCl4​?

The same elements can combine in multiple different ratios to form unique molecular compounds.

Why is it difficult to determine the formula of a molecular compound compared to an ionic compound?

Total charge of the anions.

In an ionic compound formula, the total charge of the cations must equal the _____.

Alkali metals

Which group of metals on the periodic table always carries a charge of +1 in compounds?

Nitrite

What is the name of the NO2−​ ion?

Conducting mass to mole conversions.

Which specific objective involves using Avogadro’s number in chemistry?

Silver sulfate

What is the systematic name for Ag2​SO4​?

Hypobromite

What is the name of the BrO− ion?

Iron(III) chlorite

What is the systematic name for Fe(ClO2​)3​?

Covalent bond

What type of bond forms when atoms share electrons to achieve stability?

Water has a significantly higher boiling point.

How does the boiling point of water (100∘C) compare to that of oxygen (−183∘C)?