Unit 5 Naming Ionic Compounds The Mole Hydrocarbons Percent Composition Empirical and Molecular Formulas

Unit 5 Naming and Writing Formulas for Ionic and Covalent Compounds. 6 Quick Review How can you tell whether a compound is ionic or covalent (molecular)? Ionic compounds are composed of a _________ and a _________________. A positively charged ion is a ________. Ex: K+ - which means potassium ______ an electron A negatively charged ion is an _________. Ex: Cl- which means chlorine _______ an electron.

Unit 5 Naming compounds Examples: Li + S Mg + N Fe(III) + O

Unit 5 Naming Ionic Compounds A chemical compounds name should indicate its _____________, ___________, and how it is ________ to other compounds. Compounds composed of two elements are called ___________ compounds. Compounds that contain atoms of three different elements are ___________ compounds (usually contain a polyatomic ion.

Unit 5 Naming Ionic Compounds The cation is always named first and the anion will be named second. The cation takes the name from the element. Ex: Na+ Sodium Ex: K+ Potassium The anion is named by taking the root of the elements name and adding “ide” Ex: Cl- Chloride Ex: S2- Sulfide

Unit 5 Naming Ionic Compounds Examples Na + Br Ca + Br Ga + Cl

Unit 5 Naming Ionic Compounds How to name binary compounds with multiple charges. _____________ metals all have elements with multiple charges. The cation (transition metal) is named first and the anion is named second The cation takes on the name of the element and the charge is placed in ___________. Ex: Cu+ is Copper (I) ALL transition metals must show the charge in parenthesis except Zn2+, Cd2+, Ag+

Unit 5 Naming Ionic Compounds Examples: CuCl2 Copper(II) Chloride CuCl Copper(I) Chloride Fe2O3 Iron (III) Oxide

Unit 5 Naming Ionic Compounds How to name ternary ionic compounds. First name the cation and then the polyatomic ion. The polyatomic ions usually end in “_____” or “________”. The two polyatomic ions that end in “ide” are ___________ and __________. Ex: Ca(NO3)2 K2SO4 Mg(OH)2 Fe(SO4)

Unit 5 Naming Ionic Compounds Polyatomic Ions YOU MUST MEMORIZE THE FOLLOWING POLYATOMIC IONS. Acetate (C2H3O2-) Hydroxide (OH-) Sulfate (SO42-) Sulfite (SO32-) Nitrate (NO3-) Nitrite (NO2-) Carbonate (CO32-) Ammonium (NH4+)

Unit 5 Naming Covalent Molecular Compounds Covalent compounds share electrons so there are not charges. Instead we use prefixes. Mono 1 Di 2 Tri 3 Tetra 4 Penta 5 Hexa 6 Hepta 7 Octa 8 Nano 9 Deca 10

Unit 5 Naming Molecular Compounds Examples: Give the formula for the following molecular compounds. N2O Cl2O8 SO3

Unit 5 Naming Compounds Mixed examples: Be(NO3)2 N2H4 PI3 ZnO

Unit 5 Naming Compounds Give the formula of the following molecular compounds from their names. Nitrogen trifluoride Disulfur dichloride Dinitrogen tetroxide

Unit 5 Naming Compounds Write the formulas for the following substances. Magnesium sulfide Calcium carbonate Dichlorine heptoxide Carbon tetrachloride

Unit 5 Percent Composition Taking a look at Percents….. What is the percent of boys in the class? What is the percent of girls in the class? How did you solve for this?

Percent Composition Tells a chemist how much of each element or polyatomic ion is present in a compound on a percent basis. It is the mass of an element or polyatomic ion that is present in 100 g of a compound. The percent composition has as many percent values as there are different elements in the compound

Percent Composition Compound Formula The formula of a compound shows which atoms it contains and how many atoms of each it contains. Ex: Na2S There are 2 sodium atoms and 1 sulfur atom Must know how to find molar mass of a compound from its chemical formula Ex: Find the molar mass of the compound CuSO4

Percent Composition Solving for Percent Composition % of an element = mass of element mass of compound Ex: CuSO4

Percent Composition Practice Calculate the percent composition of propane (C3H8) Calculate the percent composition of ethane (C2H6) Calculate the percent composition of sodium bisulfate (NaHSO4)

Percent Composition of Hydrates When ionic compounds are crystallized from an ionic solution they take up a definite proportion of water as a part of their structure. The compound that contains water is known as the hydrate and the water is known as the water of hydration. % water = mass of water X 100 mass of the hydrate

Percent composition of Hydrates Example CuSO4*5H2O MgSO4 *7H2O

Unit 5 The Mole 7.1 and 7.2 What is the mole and why do we use it? Atoms are extremely small which means a sample of matter contains too many atoms to count. The mole allows us to count the atoms.

Unit 5 The Mole Mole Conversions The mole is used in a number of conversions between mass, particles, and volume. 1 mole = 6.02 x 1023 particles (atoms, molecules or formula units). 1 mole = 22.4 L 1 mole = the molar mass of a substance

Unit 5 The Mole Example: Co is a metal that is added to steel to improve its resistance to corrosion. Calculate both the number of moles in a sample of Co containing 5.00 X 1020 atoms and the mass of the sample.

Unit 5 The Mole Example: Jugalone, a dye known for centuries is produced from the husks of black walnuts. It is also a natural herbicide that kills off competitive plants around the black walnut tree but does not affect grass and other noncompetitive plants. The formula for jugalone is C10H6O3. A sample of 1.56 x 10-2 g of pure jugalone was extracted from the husks. How many moles of jugalone does this sample represent?

Unit 5 The Mole Example: Calcium carbonate is the principle mineral found in limestone, marble, chalk, pearls, and the shells of marine animals like clams. A certain sample of calcium carbonate contains 4.86 moles. What is the mass in grams of this sample? What is the mass of carbonate ions present?

Unit 5 The Mole Example: Determine the volume in L of 0.60 mol sulfur dioxide gas at STP.

Unit 5 The Mole Example: How many moles is 0.880 L He?

Unit 5 Empirical/Molecular Formulas 7.3 Empirical Formulas Gives the lowest whole number ratio of the atoms of the elements in a compound Ex: Hydrogen Peroxide normally reported as H2O2 (Molecular formula). The empirical formula would be HO

Unit 5 Empirical Formula Determine the empirical formula for a compound that gives the following percentages upon analysis (in mass%). 71.65% Cl 24.27% C 4.07% H

Unit 5 Empirical Formula Step 1 - ALWAYS assume you have 100 g of the substance. Then convert the percentages to grams. 71.65 g Cl, 24.27 g C and 4.07 g H Step 2 – Convert the masses of each element to moles by dividing by the molar mass.

Unit 5 Empirical Formula Step 3 – Choose the smallest amount of moles and divide each mole amount by that number to get the ratio of atoms in the compound. Divide each one by the lowest amount.

Unit 5 Molecular Formula The exact formula of a substance. This is the formula you normally see in your book. Ex: The molecular formula for hydrogen peroxide is H2O2. You must know the molar mass of the molecular formula and the empirical formula to find the molecular formula.

Unit 5 Molecular Formula Calculate the molecular formula for the previous example. Remember the empirical formula was CClH2. The molar mass is 98.96g/mol. Step 1 – Find the Empirical Formula Step 2 – Divide the molar mass by the empirical formula mass (If you forget the larger mass will always go on top and that will always be the molar mass.

Unit 5 Molecular Formula Step 3 – multiply the number from the second step by the subscripts in the empirical formula. This will give the molecular formula. The empirical formula was CClH2 Multiply all by 2 and the molecular formula is C2Cl2H4

Unit 5 Molecular Formula A white powder is analyzed and found to contain 43.64%P and 56.36%O by mass. The compound has a molar mass of 283.88 g/mol. What are the compound’s empirical and molecular formulas?

Unit 5 Molecular Formula Caffeine, a stimulant found in coffee, tea, and chocolate, has an empirical formula of C4H5N2O, and has a molar mass of 194.2g/mol. Determine the molecular formula of caffeine.

Hydrocarbons Sections 25.1 25.2 25.3

What are hydrocarbons? Just like the name says….. They are compounds composed only of Carbon and Hydrogen!

Hydrocarbons Alkanes Contain only single covalent bonds Also referred to as saturated hydrocarbons.

Hydrocarbons Draw complete structural formulas for the straight chain alkanes that have three and four carbons.

Hydrocarbons How many single bonds are in a propane molecule?

Alkenes and Alkynes Alkenes: double bond hydrocarbons Alkynes: triple bond hydrocarbons These are also referred to as unsaturated compounds. Still follow the same chart as alkanes, but end in ene or yne instead of ane.

Alkenes and Alkynes Examples 1 – Ethene: 1 – Ethyne:

Draw the structure formula for 2-pentyne Pent is 5 yne means triple bond

Draw the structural formula for 2-Butene Bu means 4 ene means double bond

Structural Isomers Compounds that have the same molecular formula but different molecular structures Ex: Butane

Structural Isomers 2-methylpropane

Structural Isomers C5H10

Isomers

Draw a structural isomer Hexane

Name the following Isomers

Name the following Isomers