Unlocking the secret identity of chemical compounds Naming Chemicals Unlocking the secret identity of chemical compounds

Monatomic Ions Monatomic ions Ions formed from a single atom The Alkali metals lose one electron making 1+ ions The Alkali earth metals lose two electrons making 2+ ions The nitrogen family gains 3 electrons making 3- ions The oxygen family gains 2 electrons making 2- ions The Halogens gain 1 electron making 1- ions

Group 14 (carbon Family) These elements tend to not lose all the electrons but share electrons leading to different ions Sn (tin) will lose two electron from the outer P block and keep the two from the outer S block Therefore making 2+ cations

The d-block (transition elements) Can form 2+, 3+ and in a few cases 1+ or 4+ ions Many form two ions of different charges Ex. Copper forms 1+ and 2+ cations Iron and chromium 2+ and 3+ Vanadium 2+, 3+, and 4+ cations

Naming monatomic ions Monatomic cations are identified simply by the element's name. K+= Potassium cation Mg2+= Magnesium cation Monatomic anions slightly more difficult The ending to the element name is dropped and ide is added

Binary ionic compounds Compounds composed of two different elements Charges must cancel each other out so that it equals zero Ex. Al3+ O2- 3+ so need 3- Only 2- so 2 times 3+ =6+ and 3*2-= 6- Al2O3

Naming binary Ionic compounds The name of the cation is given first followed by the anion No ratios need to be given Expected to know or figure out these ratios if needed

The stock system of Nomenclature Some elements have more than one cations Need to distinguish these Do this with roman numerals Ex CuCl2 Copper(II)chloride

Binary molecular compounds Rule #1 The less-electronegative element is given first. Remember right to left up to down It only gets a prefix if it contributes more than one Rule #2 a) give a prefix indicating number B) the root of the name of the second element C) the ending -ide

Continued Rule #3 The o or a at the end of a prefix is usually dropped when the word following the prefix is a vowel Ex monoxide pentoxide

Covalent-Network Compounds Atoms is joined to neighbors by covalent bond Subscripts in formula indicate smallest whole-number ratio Similar to naming molecular compounds Ex. SiC= silicon carbide SiO2 = silicon dioxide Si3O2 = silicon dioxide Si3N4 = Trisilicon tetranitride

Acid An acid is a distinct type of molecular compound More on acids later Acid usually refers to a solution in water of one of the special compounds rather than to the compound itself Ex. Hydrochloric acid refers to a water solution of HCl.

Common Binary Acids HF=hydrofluoric acid HCl= hydrochloric acid HBr=hydrobromic acid HI=hydriodic acid H3PO4=phosphoric acid HNO2=nitrous acid HNO3=Nitric acid H2SO3=Sulfurous acid H2SO4=Sulfuric acid

Contin… CH3COOH= acetic acid HClO= hypochlorous acid HClO2= chlorus acid HClO3= chloric acid HClO4= perchloric acid H2CO3= carbonic acid

Salts An ionic compound composed of a cation and the anion from an acid Some contain anions in which one or more hydrogen atoms from the acid are retained Named by adding the word hydrogen or the prefix bi- to the anion name H2CO3 = 𝐻𝐶𝑂 − 3 Hydrogen cabonate ion Bicarbonate ion

Oxidation Numbers As a general rule oxidation numbers, shared electron are assumed to belong to the more-electronegative atom in each bond

Oxidation rules 1. the atoms in a pure element have an oxidation number of zero. Ex. Oxygen 02 2. the more-electronegative element in a binary molecular compound is assigned the number equal to the negative charge it would have as an ion. The less-electronegative same number as cation

Oxidation rules 3. Fluorine has an oxidation number of -1 in all of its compounds because it’s the most electronegative element 4. Oxygen has an oxidation number of -2 in almost all compounds. Exceptions Peroxides=-1 ex H2O2 Compounds with halogens = +2 ex OF2

Oxidation rules 5. Hydrogen has an oxidation number of +1 in compounds with element that are more electronegative -1 with metals 6. The algebraic sum of oxidation numbers of all atoms in neutral compound is zero 7. The algebraic sum in polyatomic ion is equal to charge of ion

Oxidation rules 8. Rules 1-7 apply to covalently bonded atoms but oxidation numbers can be assigned to ionic compounds The oxidation number of a monatomic ion is equal to the charge of said atom Ex. Na+ = +1 Ca += +2 Cl- = -1

Formula mass Formula mass of any molecule, formula unit or ion is the sum of the average atomic masses of all the atoms represented in its formula. Ex 𝐻 2 O H= 1.01 X 2= 2.02 O= 16.00 Average mass of water molecule= 18.02

Let’s do some 𝐻 2 𝑆𝑂 4 Ca( 𝑁𝑂 3 ) 2 Mg 𝐶𝑙 2

Molar Masses Remember that molar mass is equal to the atomic mass number. And one mole is equal to 6.022 X 10 23 particals So lets consider 𝐻 2 O again Each mole of water contains 2 moles of H 1 mole of O So H=1.01 X 2= 2.02 O=16.00 Add them together and the molar mass for water is 18.02

Conversion Factors Simple flow chart For molecules Elements Mass Moles Number of molecules Elements Mass Moles Number of particles

Lets do some What is the mass in grams of 2.50 mol of oxygen gas? How many moles of compound are there in the following? 6.60 g (𝑁𝐻 4 ) 2 𝑆𝑂 4 4.5 kg 𝐶𝑎(𝑂𝐻) 2

Percent Composition This can be very useful in determining how a molecule will form. The formula for this is 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 𝑖𝑛 𝑠𝑎𝑚𝑝𝑙𝑒 𝑜𝑓 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 𝑜𝑓 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑 X100 Lets do one Find the percentage composition of Copper(I) sulfide, Cu2S

Determining chemical formulas First step is to assume that you have a 100.0 g sample of the compound. Next using the percent composition figure out the masses of all the different elements Next using the masses of the different elements figure out the number of moles in each by using their molar masses Finally use the moles found to determine the molar ratio in the smallest whole numbers.

Lets do some Quantitative analysis shows that a compounds contains 32.38% sodium, 22.65% sulfur, and 44.99% oxygen. Find the empirical formula of this compound.

Calculation of molecular formulas Empirical formula is the lowest possible whole number ratio The molecular formula is how it appears in its natural state. X(Empirical formula)=Molecular formula