Textbook Notes (363,516)
Canada (158,391)
Chemistry (303)
CHM135H1 (52)
Chapter 2

Textbook Chapter 2.pdf

9 Pages
Unlock Document

University of Toronto St. George
C.Scott Browning

Textbook Chapter 2September11121020 PMDemocritus c 460370 BC father of atomism if you cut a piece of something smaller and smaller eventually reach particle so small you cant cut it so matter composed of tiny particles with empty space in between called them atomsAristotle impossible for nothing to exist concept of atom suppressed for 2000 years17th century Robert Boyle an element is composed of simple Bodies not made of any other Bodies of which all mixed Bodies are compounded and into which they are ultimately resolved description close to that of the element21 Elements Compounds and Mixtures An Atomic OverviewSubstance a matter whose composition is fixedElement the simplest type of matter with unique physical and chemical properties cannot be broken down into a simpler type of matter by any physical or chemical meansMolecule an independent structure of two or more atoms bound togetherCompound consists of two or more elements separated or in contact with each other sometimes made up of molecules eg ammonia water carbon dioxideAnother defining feature of a compound is that its properties are different from those of its composing elementsMixture two or more substances elements or compounds that are physically intermingled components can vary in their parts by mass retains many of the properties of its componentsMixtures can be separated into their components by physical changes22 Observations that Led to an Atomic View of MatterAtomic theory developed by John Dalton in early 19th centuryLaw of Mass Conservation 18th century the total mass of substances does not change during a chemical reaction Lavoisier first stated this on the basis of his experimentsThe number of substances may changeMass cannot be created or destroyedAlbert Einstein showed that actually mass before and after a reaction is not exactly the same some mass is converted to energy and vice versa but difference is too small to measureIn nuclear reactions energy changes are so large that mass changes are easy to observeLaw of definite or constant composition no matter the source a particular compound is composed of the same elements in the same parts by massFraction by Mass mass fraction the part of the compounds mass that each element contributes obtained by dividing the mass of each element by the mass of the compoundPercent by Mass mass percent the fraction by mass expressed as a percentage multiplied by 100Mass of element in samplemass of compound in sample x mass of element in compoundmass of compoundLaw of Multiple Proportions if elements A and B react to form two compounds the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbersEXAMPLECarbon oxide 1 is 571 massoxygen and 429 masscarbonCarbon oxide 2 is 727 massoxygen and 273 masscarbonCarbon Oxide 1Carbon Oxide 2grams oxygengrams carbon1332662661332Therefore for a given mass of carbon compound 2 contains twice as much oxygen23 Daltons Atomic TheoryDaltons postulatesAll matter consists of atoms tiny indivisible particles of an element that cannot be created or destroyedAtoms of one element cannot be converted into atoms of another element In chemical reactions atomsCHM139 Page 1
More Less

Related notes for CHM135H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.