Chapter 2 Overview. ! all matter, whether liquid, solid, or gas,consists of atoms, which form molecules

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1 Chapter 2 Overview! all matter, whether liquid, solid, or gas,consists of atoms, which form molecules! the identity of an atom and its chemical behavior is strictly defined by the number of electrons in the outer electronic sphere, which equals to the number of protons in the nucleus! the atomic weight is the combined mass of protons and neutrons in the nucleus. Each contributes one unit of mass. The mass of the electrons is negligible

2 Chapter 2 Overview 6 electrons 6 electrons 6 n o 6 p + 7 n o 6 p + 12 C 13 C number of neutrons ISOTOPES OF CARBON N = Mass - Z atomic number number of protons

3 Periodic Table Main Group Elements:Group Number corresponds to ionic charge

4 Chapter 2 Overview Ionic compounds: Simple salts. Charges Balanced NaCl Na + Cl LiI Li + I Cs 2 SO 4 Cs + SO 2 4 Fe 2 (CO 3 ) 3 Fe 3+ CO 2 3 (NH 4 ) 3 PO 4 NH + 4 PO 3 4

5 Chapter 2 Overview Molecular Weight = Sum of Atomic Weights MW(NaCl) = Atomic Mass of Na + At. Mass of Cl

6 Chapter 2 Sample Problem Succinic acid is an important metabolite in biological energy production. Give the molecular formula, empirical formula, and molecular mass of succinic acid. H O H H O C C C C O H H O succinic acid H

7 Chapter 2 Sample Problem Succinic acid is an important metabolite in biological energy production. Give the molecular formula, empirical formula, and molecular mass of succinic acid. mol. formula:count all atoms: C 4 H 6 O 4 H O H H O C C C C O H H O succinic acid H

8 Chapter 2 Sample Problem Succinic acid is an important metabolite in biological energy production. Give the molecular formula, empirical formula, and molecular mass of succinic acid. mol. formula:count all atoms: C 4 H 6 O 4 empirical formula: C 2 H 3 O 2 (whole numbers!) H O H H O C C C C O H H O succinic acid H

9 Chapter 2 Sample Problem Succinic acid is an important metabolite in biological energy production. Give the molecular formula, empirical formula, and molecular mass of succinic acid. mol. formula:count all atoms: C 4 H 6 O 4 empirical formula: C 2 H 3 O 2 (whole numbers!) H O H H O C C C C O H H O succinic acid H MW = 4! ! !16.00 =

10 Chapter 2 Sample Problem How can iodine (Z = 53) have a higher atomic number yet lower atomic weight than tellurium (Z = 52)?

11 Stoichiometry: The Mole describes quantitative aspects of chemical reactions One mole (1 mol) is 6.022!10 23 molecules (ions, atoms, etc.) Avogadro s number M = MW molar weight (g/mol) molecular weight

12 Stoichiometry MW(H 2 ) = 2.02 MW(NaCl) = MW(AgNO 3 ) = M = 2.02 g/mol M = g/mol M = g/mol 1 : 1 ratio of NaCl and AgNO 3 : g of NaCl and g of AgNO 3 or g of NaCl and g of AgNO 3 etc

13 Stoichiometry mass in grams molar weight (g/mol) M (g/mol) = m (g) n (mol) number of mols

14 Stoichiometry mass in grams molar weight (g/mol) M (g/mol) = m (g) n (mol) number of mols n (mol) = m (g) M (g/mol)

15 Stoichiometry mass in grams m (g) = n (mol)! M (g/mol) number of moles (mol) molar weight (g/mol)

16 Sample Problem 3.2 Ammonium carbonate, is a white solid that decomposes with warming. Among its many uses, it is a component of baking powder, fire extinguishers, and smelling salts. How many moles are in 41.6 g of ammonium carbonate?

17 Sample Problem 3.2 Ammonium carbonate, is a white solid that decomposes with warming. Among its many uses, it is a component of baking powder, fire extinguishers, and smelling salts. How many moles are in 41.6 g of ammonium carbonate? divide given mass by mol weight

18 Sample Problem 3.2 Ammonium carbonate, is a white solid that decomposes with warming. Among its many uses, it is a component of baking powder, fire extinguishers, and smelling salts. How many moles are in 41.6 g of ammonium carbonate? divide given mass by mol weight what is ammonium carbonate? n (mol) = m (g) M (g/mol)

19 Sample Problem 3.2 Ammonium carbonate, is a white solid that decomposes with warming. Among its many uses, it is a component of baking powder, fire extinguishers, and smelling salts. How many moles are in 41.6 g of ammonium carbonate? m (g) n (mol) = divide given mass by mol weight M (g/mol) what is ammonium carbonate? NH + 4,CO 2 3 " (NH 4 ) 2 CO 3 what is its mol. weight?

20 Sample Problem 3.2 Ammonium carbonate, is a white solid that decomposes with warming. Among its many uses, it is a component of baking powder, fire extinguishers, and smelling salts. How many moles are in 41.6 g of ammonium carbonate? m (g) n (mol) = divide given mass by mol weight M (g/mol) what is ammonium carbonate? NH + 4,CO 2 3 " (NH 4 ) 2 CO 3 what is its mol. weight? 2! ! !16.00 = g/mol

21 Sample Problem 3.2 Ammonium carbonate, is a white solid that decomposes with warming. Among its many uses, it is a component of baking powder, fire extinguishers, and smelling salts. How many moles are in 41.6 g of ammonium carbonate? n (mol) = divide given mass by mol weight what is ammonium carbonate? NH + 4,CO 2 3 " (NH 4 ) 2 CO 3 what is its mol. weight? 2! ! !16.00 = m (g) M (g/mol) g/mol answer: 41.6 g : g/mol = mol

22 Sample Problem 3.2 Ammonium carbonate, is a white solid that decomposes with warming. Among its many uses, it is a component of baking powder, fire extinguishers, and smelling salts. How many moles are in 41.6 g of ammonium carbonate? n (mol) = divide given mass by mol weight what is ammonium carbonate? NH + 4,CO 2 3 " (NH 4 ) 2 CO 3 what is its mol. weight? 2! ! !16.00 = m (g) M (g/mol) g/mol answer: 41.6 g : g/mol = mol (number of formula units = mol! 6.022!10 23 mol -1 = 2.61!10 23 )

23 Mass Percent from Chemical Formula Glucose (C 6 H 12 O 6 ) is the most important nutrient in the living cell for generating energy. What is the mass percent of each element in glucose? let s focus on carbon first

24 Mass Percent from Chemical Formula Glucose (C 6 H 12 O 6 ) is the most important nutrient in the living cell for generating energy. What is the mass percent of each element in glucose? let s focus on carbon first mass of C in one mole(cule). mass of C 6 H 12 O 6 in one mole(cule)

25 Mass Percent from Chemical Formula Glucose (C 6 H 12 O 6 ) is the most important nutrient in the living cell for generating energy. What is the mass percent of each element in glucose? let s focus on carbon first mass of C in one mole(cule). mass of C 6 H 12 O 6 in one mole(cule) 6! = = = 40.0 mass% 6! ! !

26 Elemental Analysis and Molecular Formula complete burning, than analysis of oxidation products used to determine empirical formula of an unknown compound (gives an empirical formula only!) used to confirm the structure (mass spectroscopy is a superior modern technique that gives a molecular formula directly)

27 Elemental Analysis and Molecular Formula Sample Problem 3.5: During physical activity, lactic acid (M = g/mol) forms in muscle and is responsible for muscle soreness. Elemental analysis shows that it contains 40.0 mass% C, 6.71 mass% H, and 53.3 mass% O. (a) determine the empirical formula of lactic acid (b) determine the molecular formula of lactic acid

28 Elemental Analysis and Molecular Formula Sample Problem 3.5: During physical activity, lactic acid (M = g/mol) forms in muscle and is responsible for muscle soreness. Elemental analysis shows that it contains 40.0 mass% C, 6.71 mass% H, and 53.3 mass% O. (a) determine the empirical formula of lactic acid (b) determine the molecular formula of lactic acid mass% # arbitrary weight (let s take 100 g) convert grams to moles

29 Elemental Analysis and Molecular Formula Sample Problem 3.5: During physical activity, lactic acid (M = g/mol) forms in muscle and is responsible for muscle soreness. Elemental analysis shows that it contains 40.0 mass% C, 6.71 mass% H, and 53.3 mass% O. (a) determine the empirical formula of lactic acid (b) determine the molecular formula of lactic acid mass% # arbitrary weight (let s take 100 g) convert grams to moles C = 40.0 g g/mol = 3.33 mol H = 6.71 g = 6.66 mol g/mol O = 53.3 g = 3.33 mol g/mol

30 Elemental Analysis and Molecular Formula Sample Problem 3.5: During physical activity, lactic acid (M = g/mol) forms in muscle and is responsible for muscle soreness. Elemental analysis shows that it contains 40.0 mass% C, 6.71 mass% H, and 53.3 mass% O. (a) determine the empirical formula of lactic acid (b) determine the molecular formula of lactic acid mass% # arbitrary weight (let s take 100 g) convert grams to moles C = 40.0 g g/mol = 3.33 mol H = 6.71 g = 6.66 mol g/mol O = 53.3 g g/mol = 3.33 mol CH 2 O

31 Elemental Analysis and Molecular Formula Sample Problem 3.5: During physical activity, lactic acid (M = g/mol) forms in muscle and is responsible for muscle soreness. Elemental analysis shows that it contains 40.0 mass% C, 6.71 mass% H, and 53.3 mass% O. (a) determine the empirical formula of lactic acid (b) determine the molecular formula of lactic acid Empirical formula: CH 2 O " M = g/mol Actual M is 3 (three) times greater, therefore: Molecular formula: C 3 H 6 O 3

32 Chemical Equations General Structure: Starting Material(s) # Product(s)

Chapter 2 Overview. Chapter 2 Overview

Chapter 2 Overview. Chapter 2 Overview Chapter 2 Overview! all matter, whether liquid, solid, or gas,consists of atoms, which form molecules! the identity of an atom and its chemical behavior is strictly defined by the number of electrons in