+ What’s in a name?

+ LOL ASAP FYI BRB

+ What are chemical formulas? What can a chemical formula tell us? Number of atoms of a particular element present in a chemical compound Ex. CO 2, NO 2 For ionic compounds, the ratio between the positive and negative ions within the chemical compound Ex. NaCl, MgCl 2 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

+ C 6 H 12 O 6

+ 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.

+ Example 1: Sodium chloride “salt”

+ Example 2: Aluminum oxide

+ You try….. 1) Magnesium bromide 2) Lithium chloride

+ 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

+ Example 4: Iron (III) oxide

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

+ Try….. 1) Calcium chloride 2) Copper (I) oxide 3) Sodium bromide 4) Potassium sulfide 5) Calcium oxide

+ 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 mono6 hexa 2 di7 hepta 3 tri8 octa 4 tetra9 nona 5 penta10 deca

+ Example 1: Carbon monoxide

+ Example 2: Carbon dioxide

+ 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. (NO 3 ) 2 )

+ Example 1: Silver nitrate

+ Example 2: Magnesium acetate

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

+ Classwork: 1) Potassium sulfate 12. Sodium phosphate 2) nitrogen dioxide13. 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