Lecture 1 - Atoms, ions, Molecules

element

a type of matter that is composed of atoms w/ the same atomic number, NOT: substance that cannot be broken down further

allotrope

different structural forms of the same element, ie C O S P

compound

substance that contains 2 or more elements, separated by chemical means

types of compounds (3)

binary (2 elements), ternary (3 elements), quaternary (4 elements)

polymorphs

different structural forms of the same compound in the same phase

mixture + 1 method to separate

combination of 2+ elements or compounds, separated by physical means, no breaking bonds, cannot be a pure substance, can separate via chromatography

types of mixtures (2)

heterogeneous: composition is not uniform

homogenous: composition is uniform

what are all the laws of chemical combination names (4+2extra)

law of conservation of mass, law of definite proportions, law of multiple proportions, law of combining gas volumes, also have dalton’s atomic theory of matter and avogadro’s hypothesis

law of conservation of mass

mass is neither created nor destroyed in chemical reac

law of definite proportions (from who) (another name for law?)

in pure compound, constituent elements are always present in definite proportion or % mass (dalton) (aka law of constant competition)

law of multiple proportions

reaffirm notion of atoms, when 2 elements form multiple compounds it says mass of 1 element that combined w/ fixed mass of other element are in ratio of small integers to each other

dalton’s atomic theory of matter

1. elements consist of tiny invisible particles (atoms) (WRONG - atoms can break down w/ ionization and nuclear reactions)

2. all atoms of given element are same mass and proportion (WRONG - isotopes have diff masses and proportions)

3. different elements have diff atoms w/ diff masses

4. law of definite prop

5. law of consv mass, but with atoms

law of combining gas volumes (who)

when gases (@ constant T P) react, they do so in definite integers ratio by volume, volume of product gas to volume of either reacting gas is sample ratio (gay-lussac)

avogadro’s hypothesis

equal volumes of diff gases (@ constant T P) contain = # particles, makes sense if distance between particles is big compared to particle size, ex: 1 L H gas has same # particles as 1 L O gas or N gas or HCl gas

what did dalton and avogadro believe about the particles in gases and what they were

Dalton: particles are atoms, wrong

Avogadro: could be atoms, but could also be diatomic/polyatomic, law of combining vol

Cannizzaro what’s up with him

molecules have whole # of atoms, avo is correct and equal volumes of gas have equal numbers of molecules, mass = volume gas prop to release mass of particles, mass of gas measured relative to to = vol H

Cannizzaro made set of approx atomic masses, units AMU

physical structure of atoms ideas

1. proton and neutron nucleus surounded by electrons

2. charge of nucleus = -charge of electrons, proton mass = neutron mass > electron mass

3. plum pudding, e in sea of positive charge, WRONG

talk about Millikans oil drop experiement and the cathode ray experiment

1. tube has plates, ray of cathode/beta rays stays after gas leaves so that means smth else is there, can find ratio of e charge / mass electron

2. millikan oil drop expt, drop oil through electric field and charge it and see how it stops dropping bc repelling negative plate, find e charge and thus me