Chemical Names and Formulas Chapter 7 Chemical Names and Formulas

Molecules and Molecular Compounds Molecule – the smallest electrically neutral unit of a substance that still has the properties of a substance. Molecular Compounds – Compounds composed of molecules.

Ions Ions – atoms or groups of atoms that have a positive or negative charge. Ions form when an atom or group of atoms gains or loses an electron. There are two different types of ions: anions and cations.

Cations Cation – any atom or group of atoms that has a positive charge. Ex Sodium is a cation because it has 11 protons and only 10 electrons.  Sodium has a charge of 1+ Na 1+ = Na+ (the number 1 is usually omitted)

Anions Anions – atoms or groups of atoms with a negative charge Ex Chloride is an anion because it has only 17 protons and 18 electrons. Chloride has a charge of 1- -- Cl 1- = Cl-

More Examples! Cations Symbol Anions Symbol Aluminum Al3+ Chlorate ClO3- Cobalt(II) Co2+ Fluoride F- Lead (IV) Pb4+ Hydroxide OH- Magnesium Mg2+ Nitride N3- Mercury (II) Hg 2+ Oxide O2- Potassium K + Peroxide O22-

Ionic Compounds Ionic compounds are composed of cations and anions They are usually composed of a metal cation and a non-metal anion Ex – Sodium Chloride sodium cation & chloride anion

Chemical Compounds Chemical Formula – shows the kinds & numbers of atoms in the smallest representative unit of the substance.

Diatomic Compounds They are non metallic elements Remember them!!!!! ( all 7 ) Hydrogen H2 Fluorine F2 Oxygen O2 Nitrogen N2 Chlorine Cl2 Bromine Br2 Iodine I2

Molecular Formulas Molecular Formulas show the kinds and numbers of atoms present in the molecule of a compound. Ex Ammonia = NH3 H N H H **This structural formula shows that Ammonia has 3 atoms of Hydrogen and 1 atom of Nitrogen

Formula Units Formula Units represent the lowest whole number ratio of ions in a compound. Ex Sodium Chloride 1 Na+ to each Cl- The ratio of ions is 1:1 NaCl

More Examples and Forming Compounds…. Magnesium Chloride Contains magnesium cations (Mg2+) and chloride anions (Cl-) Ratio is 1:2 Mg 2+ Cl – -- MgCl2

Aluminum Chloride Contains aluminum cations (Al3+) and chloride anions (Cl-) Ratio is 1:3 Al 3+ Cl - -- AlCl3

Type I Binary Ionic Group “A” metal – non metal Name of metal + name of non metal +ide Ex NaCl – Sodium Chloride CaBr2 – Calcium Bromide Al2O3 – Aluminum Oxide

Transition Metal – non metal Name of metal + Roman Numeral + Non Metal + ide Exceptions ( Ag+, Zn2+, Cd2+) Ex Cu2O – Copper(I) Oxide HgI2 – Mercury (II) Iodide

Type II Ternary Ionic Group “A” Metal-Radical name of metal + name of radical Transition Metal-Radical name of metal+ Roman Numeral+ name of radical

Non Metal – Non Metal Use Prefixes Mono - Hexa Di - Hepta Tri - Octa Tetra - Nona Penta - Deca Ex PCl 3 - Phosphorous Tri Chloride SF6 - Sulfur Hexa Flouride

Acids where X = mono-atomic or poly-atomic ions Give off H+ ions when dissolved in H2O Acids in form of HX where X = mono-atomic or poly-atomic ions

3 Rules 1) If X ends in - ide , acid name begins with the prefix hydro, and the stem of the anion has the suffix - ic followed by the word acid. Ex: HCl X = Chloride Hydrochloric Acid

2) If X ends in -ite , the acid name is the stem of the anion with the suffix -ous , followed by the word acid. Ex: H2SO3 X= Sulfite Sulfurous Acid

3) If X ends in - ate, the acid name is the stem of the anion with the suffix - ic, followed by the word acid. Ex: HNO3 X= Nitrate Nitric Acid

Examples HClO3 - Chloric Acid HCN - Hydrocyanic Acid H3PO4 - Phosphoric Acid HF - Hydroflouric Acid HC2H3O2 -Acetic Acid

More Examples H2SO4 - Sulfuric Acid HNO2 - Nitrous Acid Hydroiodic Acid - HI Chromic Acid - H2CrO4 Chlorous Acid - HClO2