1. IB Chemistry Power Points Topic 1 Quantitative Chemistry www.pedagogics.ca Lecture 1 The Mole and Avogadro’s Constant

2. The Structure of Matter Matter Pure Substances Mixtures Solutions Elements Compounds Covalent Ionic Atoms Molecules Formula Units Fundamental “particles” of pure substances

3. Elements - Metals Structure of metallic elements The metal solids “particles” consist of individual metal ions held together by mutual attraction for each others valence electrons.

4. Elements – Noble Gases The noble gases are the Group 8 (18) elements: He, Ne, Ar, Kr, Xe and Rn. They are extremely unreactive – considered to be inert. The fundamental particles of these elements are single atoms (monatomic).

5. Elements – Diatomic Molecules Seven elements (H, N, O, F, Cl, Br, and I) are called the diatomic elements because, as pure elements, they form molecules containing two atoms. Different representations of Cl2 The fundamental particles of these elements are molecules. Each molecule contains only one type of atom.

6. Elements – Other Structures Carbon and silicon exist as giant covalent structures – networks of atoms held together by covalent bonds. Other non-metallic elements are found in molecular form.

7. Compounds – Molecular Covalent Covalent compounds consist of groups of two or more different types of atoms bonded together into particles called molecules. Water is molecular covalent compound consisting of H2O molecules.

8. Do not confuse the forces BETWEEN molecules with the bonds WITHIN molecules covalent bonds hold hydrogen and oxygen atoms together to make water molecules intermolecular forces exist between adjacent H2O molecules

9. Compounds – Simple Ionic Ionic compounds consist of groups of ions held together by electrostatic attractions. Atoms lose or gain electrons to form cations and anions. The fundamental particle is called a formula unit. Sodium chloride is an ionic compound. The chemical formula NaCl shows the 1:1 ratio of Na to Cl in compound

10. Compounds – Simple Ionic Two representations of NaCl

11. Key Concept – “particles” is a general term referring to the fundamental components of a pure substance. This can be individual atoms, ions, small molecules, or formula units. Now we can introducethe Mole

12. A mole is a unit of quantity.A mole is 6.02 x 1023 things. 6.02 x 1023 is known as Avogadro’s constant (NA) ÷ 6.02 x 1023 Number of atoms, molecules or fundamental units Number of moles (mol) × 6.02 x 1023

13. Why the Mole? Consider one molecule of water How many molecules in 2000 mL of water? 6.7 x 1025 molecules

14. 6.7 x 1025 molecules is not a manageable number. Consider: We count eggs by the dozen We measure long periods of time in centuries. We measure long distances in our universe using light years.

15. The Mole There are many ways of measuring large quantities that utilize large units. The mole is one such unit. The mole is the SI unit for chemical quantity used to count the particles in a sample of pure substance. One mole = 6.02x1023 particles. “One mole of anything = 6.02x1023 units of that thing”

16. The Mole How many molecules of water in 2000 mL? 6.7 x 1025 molecules Or 111 mol meaning 111 moles of water molecules. This is a much more manageable number.

17. How many atoms are in 0.065 mol of copper? 3.9 x 1022 3.9 x 1022 How many molecules are in 0.065 mol of CO2? 3.9 x 1022 How many formula units are in 0.065 mol of NaCl? How many moles is 9.03 x 1023 atoms of copper? 1.5 1.5 How many moles is 9.03 x 1023 molecules of CO2? 1.5 How many moles is 9.03 x 1023 formula units of NaCl?

18. How many oxygen atoms are in 1.4 x 10-7 mol of oxygen gas (O2)? (1.4 x 10-7) × NA= 8.428 x 1016 molecules of O2 2 atoms of oxygen per molecule sofinal answer = 1.7 x 1017 atoms of oxygen (2 SF) Given 1.76 x 1012 molecules of O2, how many moles of iron III oxide (Fe2O3) can be assembled?

19. Fe2O3is an example of aChemical Formulae

20. 4 atoms of oxygen 1 atom of sulfur 2 atoms of hydrogen What are chemical formulae? ● short-hand notation ● tells us the types of elements in a compound ● gives the number of atoms of each type of element in one molecule of the compound H2SO4 sulphuric acid 1 molecule of H2SO4

21. How many atoms in each? C6H12O6 glucose Mg(NO3)2 magnesium nitrate Cu(SO4)2●5 H2O copper II sulfate hydrate

22. Relative Molecular (Formula) Mass (MR) RECALL: The average relative atomic mass (AR) for each element is noted on the Periodic Table. For example AR for copper is 63.55. Relative masses are based on 1/12th the mass of a 12C atom. The relative molecular mass is the total mass of the atoms in one molecule or formula unit of a particular compound relative to carbon-12. For example H2SO4: Hydrogen 2 atoms × 1.01 = 2.02 Sulfur 1 atom × 32.07 = 32.07 Oxygen 4 atoms × 16.00 = 64.00 MR 98.09

23. Molar MassAre you sitting comfortably?

24. Mass and the Mole: Why 6.02×1023? 1 mole = 6.02×1023 was chosen because this was then number of carbon-12 atoms that has a mass of 12 grams. Pure carbon (a mix of isotopes) has a mass of 12.01 g per mole. We call this value MOLAR MASS Consider1 atom of sulfur AR = 32.07 = 5.326×10-23 grams Consider1 mole of sulfur = 6.02×1023 atoms = 32.07 grams

25. 6.02×1023 is a REALLY BIG number Consider 6.02×1023sheets of paper stacked. How many round trips to the Moon would this stack of paper be equivalent to? 8×1010 (eighty billion ) roundtrips. Create, pick, find a mole analogy of your own. Show the math.

26. MOLARMASS Language issuegram atomic massgram molecular massgram formula mass Aluminum AR = 26.98 gram atomic mass = 26.98 g mol-1 Carbon dioxide (CO2) MR = 44.00 gram molecular mass = 44.00 g mol-1 Sodium chloride (NaCl) MR= 58.44 gram formula mass = 58.44 g mol-1

27. We weigh chemical quantities in grams. The molar mass value for a substance allows us to determine the number of moles from a measured mass. Consider 5.68 g of MgCl2 Molar mass of MgCl2 = 95.21 g mol-1

28. ÷ 6.02 x 1023 × molar mass Number of atoms, molecules or fundamental units MOLES MASS × 6.02 x 1023 ÷ molar mass

29. 1. How many moles are in 45.0 g of water? 2.50 mol 77.0 g 2. What is the mass of 1.75 mol of CO2? 9 moles 3. How many moles of oxygen atoms are in 300 g of CaCO3? 95.3 g 4. What is the mass of 9.03 x 1023 atoms of copper? 0.589 mol 5. 106 g of glucose (C6H12O6) is how many moles? 56.5 g 6. What is the mass of the oxygen atoms in 106 g of glucose?