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Chapter 9 Chemical Names and Formulas. Mr. Roberts Chemistry Level 2. Section 1 – Naming Cations. Group A Elements Just write name of metal and add “ion” to ending Example: Na +1 sodium ion Al +3 aluminum ion. Naming Cations. Group B Elements (transition metals)
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Chapter 9Chemical Names and Formulas Mr. Roberts Chemistry Level 2
Section 1 – Naming Cations Group A Elements • Just write name of metal and add “ion” to ending • Example: • Na+1 sodium ion • Al+3 aluminum ion
Naming Cations Group B Elements (transition metals) • Ionic charge will change so write Roman Numerals in parenthesis after name of metal to indicate charge. (Stock System) • Table 9.2 page 255
Naming Cations • Some post transition element also have charges that will change. • Ex: Tin and Lead • Sn+2 Sn+4 • Pb+2 Pb+4 • Some transition metals only have one ionic charge. Therefore you don’t use roman numerals. • Silver Ag+1 • Cadmium Cd+2 • Zinc Zn+2
Naming Anions • Always have the same charge! • Change suffix with - ide • Ex: F-1 Fluoride ion O-2 Oxide ion
Polyatomic Ions • Group of atoms that stay together and have an overall charge • Usually end with –ate or –ite (one less oxygen) • Ex: (SO3)-2 Sulfite (SO4)-2Sulfate (NH4)+1ammonium
Section 2 – Writing/Naming Ionic Compounds Finding the formulas for ionic compounds. • Criss-Cross Method • Remember…ionic compounds must be expressed in the lowest whole number ratio. Lose sign value
Naming Ionic Compounds • Binary Ionic Compounds (2 ions) • Use rules for naming ions • Ex: Na+1Cl-1 {sodium ion and chloride ion} NaCl Sodium Chloride
Naming Ionic Compounds (continued) • Naming Ternary Ionic Compounds (involving a polyatomic ion group) • Name it as it appears • Ex: CaCO3 calcium carbonate Mg3(PO4)2 magnesium phosphate CaSO4 calcium sulfate • If ammonium or any other polyatomic cation is reacting with a monatomic anion use binary ionic rules
Naming Group B Ionic Compounds • Rules for naming binary and ternary ionic compounds apply • Include a roman numeral in parenthesis to indicate the ionic charge. • Use the reverse of the crisscross method to determine the charge. • Ex:
Section 3 – Molecular Compounds Naming Binary molecular compounds (2 nonmetals) • Name the elements in order they appear. • Drop ending of second element and replace with suffix “ide”. • Use prefixes to indicate # of atoms present • Table 9.4 page 269
Binary Molecular Compounds Mono = 1 Di = 2 Tri = 3 Tetra = 4 Penta = 5 Hexa = 6 Hepta = 7 Octa = 8 Nona = 9 Deca = 10 Examples: N2O dinitrogen monoxide CO2 carbon dioxide CO carbon monoxide SF6 sulfur hexafluoride
9.4 Naming and Writing Acids • Acid: a compound contain H+ ions.
Examples HF HClO2 HClO3 Hydrofluoric Acid Chlorous Acid Chloric Acid
Naming and Writing Bases • Base: a compound containing OH-1 • Named in the same way as other ionic compounds • Example: NaOH sodium hydroxide
Section 9.5 – The Laws Governing Formulas and Names We are able to name compounds and write their formulas because they form from elements in predictable ways
1. The Law of Definite Proportions • In samples of any chemical compound, the masses of the elements are always in the same proportions.
2. The Law of Multiple Proportions • Whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers. • John Dalton