What’s in a name?

LOL ASAP FYI BRB Chemical formulas are shorthand method.

What are chemical formulas? What can a chemical formula tell us? Number of atoms of a particular element present in a chemical compound Ex. CO2, NO2 For ionic compounds, the ratio between the positive and negative ions within the chemical compound Ex. NaCl, MgCl2 Monoatomic ions— Ions originating from ONE atom Cation—named by element Anion—named by element, drop ending and add –ide ending Ex. O-2, N-3, Mg+2

C6H12O6

Binary Compounds—Writing Chemical formulas 1) Cation, Anion. (write element symbols) 2) Write oxidation number/charge on each element. 3) Balance charges by the smallest common multiplier between the two elements. Charges must add to 0 for a neutral compound. 4) Add the subscripts for each element in the chemical compound. Dealing with two elements “bi” –metal/nonmetal

Example 1: Sodium chloride “salt” NaCl

Example 2: Aluminum oxide Al2O3

You try….. Magnesium bromide Lithium chloride MgBr2 LiCl

5) If the first element is a transition element, the oxidation number or charge of the element is given by a Roman numeral (I, II, III, IV, etc.) following the element name. Exceptions: Ag+1 and Zn+2—they will always have these charges.  

Example 3: Tin (IV) sulfide SnS2

Example 4: Iron (III) oxide Fe2O3

You Try….. 1) Zinc oxide 2) Mercury (II) fluoride 1) ZnO 2) HgF2

Try….. Calcium chloride Copper (I) oxide Sodium bromide Potassium sulfide Calcium oxide CaCl2 Cu2O NaBr KS2 CaO

Binary Compounds—Writing Chemical formulas (Cont.) 6) If a binary compound has a prefix or prefixes in front of an element name, these prefixes are the subscripts for that element in the chemical formula. Prefixes represent the number of element atoms present in a molecule of the chemical compound.

Prefixes 1 mono 6 hexa 2 di 7 hepta 3 tri 8 octa 4 tetra 9 nona 5 penta 10 deca

Example 1: Carbon monoxide CO

Example 2: Carbon dioxide CO2

You Try….. Diphosphorus trioxide Iodine heptafluoride Carbon tetrachloride

Polyatomic Chemical Compounds—Writing Chemical Formulas. 1) Cation, Anion—reference table, Element Symbols 2) Immediately put ( ) around polyatomic ion 3) Write the oxidation number/charge on each element and polyatomic ion. 4) Balance charges by the smallest common multiplier. Charges must add to 0 for a neutral compound. 5) Add the subscripts for each element/polyatomic ion and drop the ( ) around polyatomic if you can. *Polyatomic ions: place polyatomic ions in parentheses when adding subscript (ex. (NO3)2) **1st step—write the element symbol or polyatomic ion symbol for each. IMMEDIATELY enclose polyatomic ions in ()

Example 1: Silver nitrate AgNO3

Example 2: Magnesium acetate Mg (CH3CO2)2

You try….. 2) Calcium carbonate 3) Magnesium Phosphate 1) Ammonium chloride 2) Calcium carbonate 3) Magnesium Phosphate 4) Ammonium sulfate NH4Cl CaCO3

Classwork: 1) Potassium sulfate 12. Sodium phosphate 2) nitrogen dioxide 13. Dinitrogen pentaoxide 3) sulfur tetrabromide 14. Carbon tetrahydride 4) magnesium phosphate 15. Calcium nitrate 5) sodium sulfate 6) phosphorus pentachloride 7) selenium trichloride 8) chromium (III) nitrite 9) iodine dioxide 10) magnesium hydroxide 11) Mercury (II) hydroxide