RIP W. E. B. DuBois (1963) Read for Tuesday Read for Tuesday Chapter 3: Sections 1-2 Chapter 3: Sections 1-2 HOMEWORK – DUE Tuesday 9/1/15 HOMEWORK – DUE Tuesday 9/1/15 HW-BW 1 (Homework Bookwork) #’s 4-9 all, 21, 26, 30, 36, 39, 44, 47, 49, odd, 78, 80, 81 HW-BW 1 (Homework Bookwork) #’s 4-9 all, 21, 26, 30, 36, 39, 44, 47, 49, odd, 78, 80, 81 HW-WS 1 (Homework Worksheet) (from course website) HW-WS 1 (Homework Worksheet) (from course website) HOMEWORK – DUE Thursday 9/3/15 HOMEWORK – DUE Thursday 9/3/15 HW-BW 2 (Homework Bookwork) #’s 1-7 all, 14, 19, 21, 23, 36, all, 57, all, 81, 82, 113, 114, 116, 127, 132 HW-BW 2 (Homework Bookwork) #’s 1-7 all, 14, 19, 21, 23, 36, all, 57, all, 81, 82, 113, 114, 116, 127, 132 HW-WS 2 (Homework Worksheet) (from course website) HW-WS 2 (Homework Worksheet) (from course website) Lab Monday/Tuesday Lab Monday/Tuesday EXP #1- PRELAB!!!! EXP #1- PRELAB!!!!

Classification of Matter Matter that is constant in its chemical composition and properties. Pure Substance: Matter that is constant in its chemical composition and properties. A blend of two or more pure substances in any ratio each retaining their identity. Mixture: A blend of two or more pure substances in any ratio each retaining their identity. Physical changes can separate mixtures into one or more pure substances.

Element Elements are substances that cannot be broken down chemically into simpler substances. Elements are substances that cannot be broken down chemically into simpler substances. All of the atoms that make up a particular element are chemically the same as all of the others All of the atoms that make up a particular element are chemically the same as all of the others All of the atoms that make up a particular element contain the same number of protons as all other atoms of that element. All of the atoms that make up a particular element contain the same number of protons as all other atoms of that element.

Pure Substances Two or more elements combined chemically in specific ratios to form a pure substance. Chemical Compounds: Two or more elements combined chemically in specific ratios to form a pure substance. Water = H 2 O Methanol = CH 3 OH Nitroglycerine = C 3 H 5 (NO 3 ) 3

Mixtures Heterogeneous Mixture: A mixture of matter in which the properties change from sample to sample. Hetero change Sand and sugar Quartz and gold

Mixtures Homogeneous Mixture: A mixture of matter in which the properties remain constant from sample to sample. Homo constant Salt water Kool-Aid Brass

Classification of Matter Label each of the following as either: element, compound, homogenous mixture or heterogeneous mixture Carbon dioxide Tea brewed from tea bags Water, distilled and deionized Oxygen gas An egg Apple Juice compound homogenous mixture compoundelement heterogeneous mixture homogenous mixture

Before There Were Atoms… Three laws that lead to the atomic view of the atom: 1) Law of Conservation of Mass Total mass must be same before and after a reaction 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio 3) Law of Multiple Proportions If two elements combine to form more than one type of compound with each other, the masses of one element that combined with a fixed mass of the other element are in ratios of small whole numbers

Before There Were Atoms… Three laws that lead to the atomic view of the atom: 1) Law of Conservation of Mass Total mass must be same before and after a reaction I am BBQing and start with 20 pounds of charcoal. When I am done, there is only 4 pounds of ash left. How can we explain the apparent failure of the Law of Mass Conservation? 48.0 g of carbon react with 128 g of oxygen, how much CO 2 should be formed? 176 g CO 2(g) 48.0 g of carbon react with 148 g of oxygen. After the reaction is complete, there is still only 176 g of CO 2 formed. Has the Law of Conservation of Mass failed? 20.0 g O 2(g) left over

48.0 g of carbon react with 128 g of oxygen, forming 176 g CO 2, how much CO 2 should be formed from 72.0 g of carbon? Before There Were Atoms… Three laws that lead to the atomic view of the atom: 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio X = 264 g CO 2(g)

48.0 g of carbon react with 128 g of oxygen, forming 176 g CO 2, how much O 2 should be react with 72.0 g of carbon? Before There Were Atoms… Three laws that lead to the atomic view of the atom: 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio 48.0 g of carbon react with 128 g of oxygen, forming 176 g CO 2, how much O 2 should be react with 72.0 g of carbon? X = 192 g O 2(g)

Before There Were Atoms… Three laws that lead to the atomic view of the atom: 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio A kg sample of NaCl from The Great Salt Lake contains 86.4 kg of sodium, what mass of chloride would be present in a 76.8 kg sample of NaCl from the Dead Sea? X = 46.8 kg Cl kg NaCl – 86.4 kg Na = kg Cl A kg sample of NaCl from The Great Salt Lake contains 86.4 kg of sodium, what mass of chloride would be present in a 76.8 kg sample of NaCl from the Dead Sea? kg NaCl – 86.4 kg Na = kg Cl

Before There Were Atoms… Three laws that lead to the atomic view of the atom: 3) Law of Multiple Proportions If two elements combine to form more than one type of compound with each other, the masses of one element that combined with a fixed mass of the other element are in ratios of small whole numbers 16.0 g of oxygen react with 2.0 g of hydrogen 64.0 g of oxygen react with 4.0 g of hydrogen g of oxygen g of hydrogen 16.0 g of oxygen g of hydrogen

Before There Were Atoms… Three laws that lead to the atomic view of the atom: 3) Law of Multiple Proportions If two elements combine to form more than one type of compound with each other, the masses of one element that combined with a fixed mass of the other element are in ratios of small whole numbers 89.4 g of oxygen react with 33.6 g of carbon 50.5 g of oxygen react with 37.9 g of carbon

The Atom REALLY early atomic theory… REALLY early atomic theory… Democritus ~350 BC Democritus ~350 BC Atomos - Greek meaning indivisible Atomos - Greek meaning indivisible Modern Definition: Modern Definition: Smallest piece that matter can be broken up into and still maintain the properties of an element Smallest piece that matter can be broken up into and still maintain the properties of an element

My Atom Broke Subatomic Particles Subatomic Particles Nucleus Nucleus Protons – p + Protons – p + Carry a single positive charge Carry a single positive charge Number of p + = ATOMIC NUMBER Number of p + = ATOMIC NUMBER 1.673x g 1.673x g

My Atom Broke Subatomic Particles Subatomic Particles Nucleus Nucleus Neutrons – n o Neutrons – n o No charge No charge # can vary from atom to atom # can vary from atom to atom 1.675x g (roughly the same mass as p + ) 1.675x g (roughly the same mass as p + )

My Atom Broke Subatomic Particles Subatomic Particles Outside the nucleus Outside the nucleus Electrons – e - Electrons – e - Carry a single negative charge Carry a single negative charge ~1830 e - = mass of p + or n o ~1830 e - = mass of p + or n o 9.11x g 9.11x g Responsible for most of the chemistry that ever happens Responsible for most of the chemistry that ever happens

Atoms vs. Ions Atoms are !!!!! Atoms are NEUTRAL!!!!! This means that they have zero charge This means that they have zero charge #p + = #e - #p + = #e -

Charge!!! 1 p + 1 e – – 0 47 p + 47 e – + 0 When #p + = #e -, the atom has no charge and is neutral

Atoms vs. Ions Atoms can gain or lose e - to form IONS Atoms can gain or lose e - to form IONS ANY charged particle is called an ANY charged particle is called an ion Losing e - gives charge Losing e - gives POSITIVELY charge

10 e - =11 e - = Charge!!! When an atom LOSES electrons 10 e – 11 p + = 11 p + – +1 Na Na  Na + Na  Na + + e- BeforeAfter