1 Announcements & Agenda (01/17/07) Office Hours cancelled today (Red Wings) CD quizzes due NOW Quiz 2 today! See overhead for your clicker number You should currently be reading Ch 3 You should currently be reading Ch 3 Today: Finish Heating/Cooling Curves (Ch 2) Finish Heating/Cooling Curves (Ch 2) Classification of Matter (3.1) Classification of Matter (3.1) Elements, Atoms, & Subatomic Particles ( ) Elements, Atoms, & Subatomic Particles ( )

2 Heat = mass x  T x (Specific Heat) The amount of heat lost or gained by a substance is calculated from the mass of substance (g).mass of substance (g). temperature change (  T).temperature change (  T). specific heat of the substance (J/g°C).specific heat of the substance (J/g°C). Last Time: Heat Energy Key Point: If one substance “heats up” by a certain amount, another substance must exactly lose that same amount of heat!

3 Last Time: Phases Changes melting vaporization condensation freezing deposition sublimation (e.g. freeze-drying)

4 Last Time: Heat of Fusion/Vaporization Measure of heat energy released/absorbed during the appropriate phase change for 1 g of substance Water: Heat of MP = 80. cal 1 g water 1 g water Water: Heat of BP = 540. cal 1 g water 1 g water

5 Summary of Heating Processes: Heating Curves A heating curve illustrates the changes of state as a solid is heated.illustrates the changes of state as a solid is heated. uses sloped lines to show an increase in temperature.uses sloped lines to show an increase in temperature. uses plateaus (flat lines) to indicate a change of state.uses plateaus (flat lines) to indicate a change of state.

6 Cooling Curve Using the heating curve of water as a guide, draw a cooling curve for water beginning with steam at 110°C and ending at -20°C.

7 To reduce a fever, an infant is packed in 250. g of ice. If the ice (at 0°C) melts and warms to body temperature (37.0°C), how many calories are removed from the body? Step 1: Diagram the changes 37°C  T = 37.0°C - 0°C = 37.0°C 37°C  T = 37.0°C - 0°C = 37.0°C temperature increase temperature increase 0°C solid liquid 0°C solid liquid melting melting Combined Heat Calculations

8 Combined Heat Calculations (continued.) Step 2: Calculate the heat to melt ice (fusion) 250. g ice x 80. cal=  10 4 cal 1 g ice 1 g ice Step 3: Calculate the heat to warm the water from 0°C to 37.0°C (SH of water = 1 cal/g) 0°C to 37.0°C (SH of water = 1 cal/g) 250. g x 37.0°C x 1.00 cal = cal g °C 250. g x 37.0°C x 1.00 cal = cal g °C Total: Step 2 + Step 3 = cal (rounded to 3 SF)

9 29 Good Practice Problems (Ch 3) 3.03, 3.05, 3.07, 3.11, 3.15, 3.17, 3.19, 3.23, 3.29, 3.35, 3.37, 3.41, 3.49, 3.51, 3.55, 3.59, 3.65, 3.67, 3.69, 3.73, 3.77, 3.79, 3.81, 3.85, 3.91, 3.95, 3.97, 3.101, 3.103

10 Chemistry: The Study of the Properties & Behavior of Matter Pure substance: matter with fixed/definite composition Elements: substance composed of only one type of atom Compounds: combination of 2 or more elements in same ratio (e.g. water, carbon dioxide, sodium chloride) Mixtures: two or more substances that can be separated by physical means Heterogeneous mixtures: non-uniform distribution of substances (e.g. mud = sand and saltwater, chocolate chip cookie) Homogenous mixtures: uniform distribution of substances (e.g. saltwater = salt and water, air, Kool Aid)

11 Visual Summary

12 Elements Pure substances that cannot be separated into different substances by chemical processes Pure substances that cannot be separated into different substances by chemical processes Are the building blocks of matter (the ABCs) Are the building blocks of matter (the ABCs) 112 elements known today 112 elements known today Examples: carbon goldcalcium

13 Symbols of Elements Use 1 or 2 letter abbreviations Use 1 or 2 letter abbreviations Capitalize the first letter only Capitalize the first letter onlyExamples: C carbon Cocobalt N nitrogenCacalcium F fluorine Br bromine O oxygen Mg magnesium

14 Symbols from Latin Names ElementSymbolLatin name CopperCucuprum GoldAuaurum LeadPbplumbum MercuryHghydrargyrum PotassiumKkalium SilverAgargentum SodiumNanatrium TinSnstannum

15 % Major Elements in the Body (Know These!) O65.0 %K 0.34 C18.0S 0.26 H10.0Na 0.14 N 3.0Cl 0.14 Ca 1.4Fe P 1.0 Zn Mg 0.50 Trace Elements As, Cr, Co, Cu, F, I, Mn, Mo, Ni, Se, Si, V

16 Atoms are building blocks of elements Atoms are building blocks of elements Similar atoms in each element Similar atoms in each element Different from atoms of other elements Different from atoms of other elements Two or more different atoms bond in simple ratios to form compounds Two or more different atoms bond in simple ratios to form compounds Dalton’s Atomic Theory Dalton’s Atomic Theory

17 Conservation Laws 1.Atoms are conserved during physical and chemical transformations – atoms are neither created nor destroyed during a chemical or physical process 2.Mass is conserved during physical and chemical transformations – mass is neither created nor destroyed during a chemical or physical process 3. Charge is also conserved during physical and chemical transformations

18 Methane (CH 4 ) reacts with oxygen (O 2 ) to produce carbon dioxide (CO 2 ) and water (H 2 O). COUNT THE ATOMS! SEE BOB DEMO!

19 Subatomic Particles Atoms contains subatomic particles, protons have a positive (+) charge.protons have a positive (+) charge. electrons have a negative (-) charge.electrons have a negative (-) charge. like charges repel and unlike charges attract.like charges repel and unlike charges attract. neutrons are neutral.neutrons are neutral.

20 Structure of the Atom dense nucleus that contains protons and neutrons.dense nucleus that contains protons and neutrons. of electrons in a large empty space around the nucleus.of electrons in a large empty space around the nucleus.

21 Atomic Mass Scale On the atomic mass scale for subatomic particles, 1 atomic mass unit (amu) has a mass equal to 1/12 of the mass of the carbon-12 atom.1 atomic mass unit (amu) has a mass equal to 1/12 of the mass of the carbon-12 atom. a proton has a mass of about 1 (1.007) amu.a proton has a mass of about 1 (1.007) amu. a neutron has a mass of about 1 (1.008) amu.a neutron has a mass of about 1 (1.008) amu. an electron has a very small mass, amu.an electron has a very small mass, amu.

22 Summary

23 Atomic Number = The Identity of the Element Counts the number ofprotons in an atom

24 All Atoms of the Same Element Have the Same # of Protons!!! 11Na 11 protons Symbol

25

26 Mass Number Since protons and neutrons account for most of the mass of the atom, count the number of protons and neutrons to determine the mass number!!! to determine the mass number!!!

27 represents a particular atom of an element.represents a particular atom of an element. gives the mass number in the upper left corner and the atomic number in the lower left corner.gives the mass number in the upper left corner and the atomic number in the lower left corner. Example: An atom of sodium with atomic number 11 and a mass number 23 has the following atomic symbol: Example: An atom of sodium with atomic number 11 and a mass number 23 has the following atomic symbol: mass number 23 mass number 23 Na Na atomic number11 atomic number11 Nuclear Symbol

28 An atom of an element is electrically neutral; the net charge of an atom is zero.an element is electrically neutral; the net charge of an atom is zero. has an equal number of protons and electrons.has an equal number of protons and electrons. number of protons = number of electrons Aluminum has 13 protons and 13 electrons. The net charge is zero. 13 protons (13+) + 13 electrons (13 -) = 0 13 protons (13+) + 13 electrons (13 -) = 0 Electrons in An Atom