Rules in naming of chemical formulas and their types

What do chemical formulas represent?

Chemical formulas represent the composition of compounds, showing which elements are present and the number of atoms of each.

What does a molecular formula show?

The actual number of atoms of each element in a molecule (e.g., C₆H₁₂O₆ for glucose).

What does an empirical formula show?

The simplest whole-number ratio of atoms in a compound (e.g., CH₂O for glucose).

What does a structural formula show?

How atoms are bonded together within a molecule, including single, double, or triple bonds. Useful for identifying molecular shape and functional groups (e.g., H-O-H for water).

What are Lewis structures and what do they show?

A detailed type of structural formula that shows valence electrons as dots, with bonding pairs represented by lines and lone pairs by dots. They help explain bonding, molecular shape, and reactivity.

What does a ball-and-stick model show?

The 3D arrangement of atoms and bond angles.

What does a space-filling model show?

The relative atomic sizes and the overall shape of the molecule.

What are the two main types of chemical models and what do they help with?

Ball-and-stick models and space-filling models, both of which help visualize molecular geometry and interactions.

What is the composition of ionic compounds?

Made up of a cation (metal) and an anion (nonmetal or polyatomic ion).

What are binary ionic compounds and how are they named?

Binary ionic compounds have two elements; name the cation first, then the anion, which typically ends in "-ide".

Give three examples of binary ionic compounds.

NaCl (sodium chloride), KBr (potassium bromide), ZnI₂ (zinc iodide).

What are ternary ionic compounds?

Compounds with more than two elements, usually involving polyatomic ions.

Give two examples of ternary ionic compounds.

LiOH (lithium hydroxide), KCN (potassium cyanide).

What is the Stock System used for?

Naming ionic compounds with metals that can form multiple charges by indicating the charge of the cation with Roman numerals.

Give two examples of compounds named using the Stock System.

FeO (Iron(II) oxide), Fe₂O₃ (Iron(III) oxide).

What is the crisscross method used for?

Writing formulas from names by exchanging the numerical values of the charges to become subscripts for the opposite element/ion.

Give three examples of chemical formulas written using the crisscross method.

Aluminum oxide (Al₂O₃), Manganese(III) oxide (Mn₂O₃), Copper(II) nitrate (Cu(NO₃)₂).

What are molecular compounds composed of?

Nonmetallic elements.

Rules in naming to apply on molecular compounds

Use Greek prefixes to indicate the number of atoms of each element; the second element ends in "-ide"; drop "mono-" for the first element and drop "a" in a prefix if followed by a vowel.

List the Greek prefixes for numbers 1 to 10 in molecular compound naming.

mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), hexa- (6), hepta- (7), octa- (8), nona- (9), deca- (10).

Give four examples of molecular compound names and formulas.

N₂O₄ (dinitrogen tetraoxide), NO₂ (nitrogen dioxide), CCl₄ (carbon tetrachloride), S₂O₈ (disulfur octoxide).

What are acids and what do they yield in water?

Substances that yield hydrogen ions (H⁺) when dissolved in water.

What is the general formula structure of acids?

Contain one or more hydrogen atoms and an anionic group.

What are binary acids and how are they named?

Acids whose anion ends with "-ide", named with a "hydro-" prefix and an "-ic" ending (e.g., HF = hydrofluoric acid).

Give three examples of binary acids.

HF (hydrofluoric acid), HCl (hydrochloric acid), H₂S (hydrosulfuric acid).

What are oxoacids and how are their formulas typically written?

Acids containing hydrogen, oxygen, and another central element, written as H, then central element, then O (e.g., HNO₃, H₂SO₄).

Give four examples of oxoacids.

HNO₃ (nitric acid), H₂CO₃ (carbonic acid), H₂SO₄ (sulfuric acid), HClO₃ (chloric acid).

What happens to acid names when the number of oxygen atoms changes?

Add 1 oxygen: "per…-ic" acid; remove 1 oxygen: "-ous" acid; remove 2 oxygen: "hypo-…-ous" acid.

Give an example of an acid with one more oxygen than its "-ic" form.

HClO₄ (perchloric acid) from HClO₃ (chloric acid).

Give an example of an acid with one less oxygen than its "-ic" form.

HNO₂ (nitrous acid) from HNO₃ (nitric acid).

Give an example of an acid with two fewer oxygens than its "-ic" form.

HBrO (hypobromous acid) from HBrO₃ (bromic acid).

What are bases and what do they yield in water?

Substances that yield hydroxide ions (OH⁻) when dissolved in water.

How are bases named?

Name the metal first, then add "hydroxide".

Give three examples of bases.

NaOH (sodium hydroxide), KOH (potassium hydroxide), Ba(OH)₂ (barium hydroxide).

What are hydrates?

Compounds with a specific number of water molecules attached to them.

How are hydrates named?

Name the compound normally, then add "hydrate" with the appropriate Greek prefix.

Give two examples of hydrates.

BaCl₂ · 2H₂O (barium chloride dihydrate), CuSO₄ · 5H₂O (copper(II) sulfate pentahydrate).

What does "anhydrous" mean in chemistry?

When water molecules are removed from a hydrate.

What is the difference between a common name and a systematic name for a compound?

Common names are historical/colloquial; systematic names follow IUPAC rules.

Give three examples of compounds with both common and systematic names.

H₂O (Water / Dihydrogen monoxide), NH₃ (Ammonia / Nitrogen trihydride), NaCl (Table salt / Sodium chloride).

Acid

A substance that yields hydrogen ions (H⁺) when dissolved in water.

Anhydrous

A compound from which all water molecules have been removed; refers to a hydrate that has lost its water of crystallization.

Anion

A negatively charged ion.

Atom

The basic unit of a chemical element.

Ball-and-Stick Model

A type of chemical model that shows the 3D arrangement of atoms and bond angles in a molecule, with spheres representing atoms and sticks representing bonds.

Base

A substance that yields hydroxide ions (OH⁻) when dissolved in water.

Binary Compound

A chemical compound composed of only two different elements.

Cation

A positively charged ion.

Chemical Formula

A representation that shows the elements present in a compound and the number of atoms of each element.

Crisscross Method

A method used to write chemical formulas for ionic compounds by exchanging the numerical values of the charges of the cation and anion to become subscripts.

Empirical Formula

A chemical formula that shows the simplest whole-number ratio of atoms in a compound.

Functional Group

A specific group of atoms within a molecule that is responsible for the characteristic chemical reactions of that molecule.

Greek Prefixes

Prefixes (mono-, di-, tri-, etc.) used in chemical nomenclature to indicate the number of atoms of an element in a molecular compound or the number of water molecules in a hydrate.

Hydrate

A compound that contains a specific number of water molecules chemically bound within its crystal structure.

Hydrocarbon

An organic compound consisting entirely of hydrogen and carbon.

Ionic Compound

A chemical compound formed by the electrostatic attraction between oppositely charged ions, typically between a metal and a nonmetal.

Lewis Structure

A detailed structural formula that shows the arrangement of atoms, bonding pairs of electrons (as lines), and lone pairs of electrons (as dots) around individual atoms.

Lone Pair

A pair of valence electrons that are not shared with another atom in a covalent bond and are associated with a single atom.

Molecular Compound

A chemical compound composed of two or more nonmetallic elements, typically held together by covalent bonds.

Molecular Formula

A chemical formula that shows the actual number of atoms of each element in a molecule.

Nomenclature

A system of naming chemical compounds.

Oxoacid

An acid that contains hydrogen, oxygen, and at least one other element (the central element).

Polyatomic Cation/Anion

An ion composed of two or more atoms covalently bonded together that carries an overall positive (cation) or negative (anion) charge.

Space-Filling Model

A type of chemical model that represents the relative sizes of atoms and the overall shape of a molecule, showing how electron clouds overlap.

Stock System

A method of naming ionic compounds, especially those involving transition metals, where Roman numerals are used in parentheses to indicate the charge of the metal cation.

Structural Formula

A chemical formula that shows how the atoms in a molecule are bonded to each other, often indicating single, double, or triple bonds.

Ternary Compound

A chemical compound composed of three different elements.

Valence Electrons

The electrons in the outermost shell of an atom, which are involved in chemical bonding.