Chemical Formulas-Covalent Chapter 6 Sections 5-6

Properties of Ionic Compounds Most ionic compounds are solid at room temperature Dissolve in water Conduct electricity when in the molten state or dissolved in water Very high melting points. (strongest bond) Examples: Acids, bases and salts

Properties of Covalent Compounds Can exist as gases, liquids, or solids depending on molecular mass or polarity Usually have lower MP and BP than ionic compounds Do not usually dissolve in water Do not conduct electricity

Covalent Formula-2 nonmetals! Uses prefixes with the ending –ide on the second element! Phosphorous is a nonmetal Name: Trinitrogen diphosphide N3P2 2 phosphorous atoms Nitrogen symbol A Subscript: 3 nitrogen atoms

Molecular Formulas AKA Special binary. These are binary compounds made up of two non-metals These have a special set of rules used only when ______________ and ____________ combine.

Naming Molecular Compounds Ask yourself- Are there only two elements? if yes.. Is the first element not hydrogen? If yes.. Is the first element a nonmetal? If yes.. Congratulations! You have a special binary formula that uses the following prefixes and rules! But only use these rules if you answered yes to the three questions above…

Binary Covalent Formulas  Compounds between two nonmetals  First element in the formula is named first.  Second element is named as if it were an anion.  Use prefixes  Never use mono on the first element’s name P2O5 = diphosphorus pentoxide

Prefixes for Molecular Formulas 1 mono 2 di 3 tri 4 tetra 5 pent 5 hex 7 hept 8 oct 9 non 10 dec LEARN THESE

Examples Carbon dioxide CO2 Xenon hexaflouride XeF6 Dinitrogen Monoxide N2O You try Phosphorus trichloride CO Carbon tetrachloride Check answers

Naming Acids These are the easiest and the trickiest set of rules to learn! Get our your sheet from the last chapter, “Valences of common ions” Look for the element Hydrogen at the start of the formula… If you have two elements it’s one set of rules If you have more it’s another set of rules.

Binary Acid - HX HX Hydro__x__ic acid Example HCl Hydrochloric acid HBr Hydrobromic acid H2S Hydrosulfic acid

Ternary Acid Ignore the hydrogen and look at the polyatomic ion and its ending Change the ending according to the following and add the word acid If the anion name ends in -ate, then the acid name ends in -ic or -ric. If the anion name ends in -ite, then the acid name ends in -ous.  

Acid Names from Anion Acid Anion Acid Name HClO hypochlorite hypochlorous acid HClO2 chlorite chlorous acid HClO3 chlorate chloric acid HClO4 perchlorate perchloric acid

Prior and proper practice makes perfect…. This unit absolutely requires that you practice using the naming rules! That’s why there are several worksheets These items also appears on the TAKS test, so I don’t want you to just learn it for the test and forget the information!

Answers to Sample Problems PCl3 Carbon monoxide CCl4 Back to Examples