Gen Chem 1 Lecture 1

Front 1

what is the most abundant element on earth by mass?

Back 1

oxygen

Front 2

what is the haber process

Back 2

synthesis of NH3 from N2 and H2

Front 3

Define element (Dalton's definition)

Back 3

element that cannot be broken down into a simpler substance through ORDINARY chemical or physical means (not nuclear rxn or radioactive decay)

Front 4

Most clear definition of element

Back 4

a type of matter that is composed of atoms with the same atomic number; only corresponds to ONE of the symbols on the periodic table

Front 5

atomic number

Back 5

number of protons

Front 6

Is Ozone (O3) an elemental form of O? why/why not

Back 6

YES...all ozone atoms have same atomic #

Front 7

isotope

Back 7

elements of different mass number

Front 8

Allotrope: definition

Back 8

different STRUCTURAL form of the same element (ONLY elements) in the same state of matter (phase)

Front 9

Are oxygen gas and liquid oxygen allotropes?

Back 9

NO, different states of matter

Front 10

examples of carbon allotropes

Back 10

diamond, graphite, buckyball (all solid, all elemental carbon)

Front 11

Polymorph

Back 11

structural differences of COMPOUNDS; not elements

Front 12

Pure substance vs. material

Back 12

pure substances are only compounds or elements, materials could be anything else

Front 13

Define compound

Back 13

pure substance that contains two or more elements

Front 14

Binary compound

Back 14

contains two elements (water, carbon dioxide, carbon monoxide, etc.)

Front 15

Ternary compound

Back 15

contains three elements (ethanol: C2H5OH)

Front 16

Quaternary compound

Back 16

contains 4 elements (trifluroethanol: CF3CH2OH)

Front 17

Define mixture

Back 17

combination of two or more elements or compounds

Front 18

Heterogenous mixture

Back 18

components of the mixture are not uniformly distributed, have localized regions (oil in water, milk)

Front 19

Homogenous mixture

Back 19

components of the mixture evenly distributed and indistinguishable (air, solutions)

Front 20

Is a solid mixture of NaCl and KCl homogenous?

Back 20

NO...even if ground very finely the separate parts to the mixture will still be present

Front 21

can mixtures be separated

Back 21

yes, through physical means (evaporation, distillation, filtration)

Front 22

original Greek concept of the atom

Back 22

matter will be divided until its smallest part, which will be indivisible...called the atom

Front 23

Law of Conservation of Mass: who, what

Back 23

Lavoisier; matter neither created nor destroyed during a chemical rxn

Front 24

Analyzing the respective weights of products and reactants in chemical reactions led to what 2 laws?

Back 24

Law of Conservation of Mass, Law of Definite proportions

Front 25

Law of Definite Proportions: who, what

Back 25

Proust; in a pure compound, the constituent elemnts are always present in a definite proportion or % by mass

Front 26

Law of Constant Composition:

Back 26

equivalent statement to law of definite proportions: all samples of a given chemical compound have same elemental composition (examples: water is always 11.1% H and 88.9% O)

Front 27

Law of Multiple Proportions

Back 27

when two elements form a series of compounds, the masses of one element that combine with a fixed mass of the other element are in the ratio of small integers

Front 28

Dalton's Atomic Theory Postulates

Back 28

1. elements consist of tiny indivisible particles: atoms
2. all atoms of an element are identical (mass/properties)
3. different elements have different atoms (unique mass)
4. compounds are formed when atoms of UNLIKE elements combine in whole # ratios)
5. Atoms retain their identities in a chemical process and a rxn only changes the way things are bonded together

Front 29

What of Dalton's Atomic theory has been proven wrong?

Back 29

1. atoms ARE divisible (by ionization- adding e- or nuclear rxns)

2. all atoms of an element are NOT identical (isotopes- different mass and properties)

Front 30

Dalton's rule of greatest simplicity

Back 30

if two elements form only a single compound then its molecules will have the simplest formula possible: ex. elements A and B form AB

Front 31

problems arising from Dalton's rule of greatest simplicity

Back 31

water called HO, ammonia called NH-- led to problems with discoveries of atomic masses

Front 32

Law of Combining Gas Volumes

Back 32

gases at the same pressure and temperature react, they do so in a definite integer ratio by volume; Gay-Lussac

Front 33

How did Avogadro apply Gay-Lussac gas volumes?

Back 33

he applied the results: equal volumes of different gases at teh same temperature and pressure contain equal number of PARTICLES (1 L of hydrogen gas has the same # of particles as 1L of Nitrogen gas, etc.)

Front 34

Dalton on Avogadro's interpretation of combining gas volumes?

Back 34

Dalton believed that particles were atoms, while Avogadro theorized about diatomic or polyatomic molecules

Front 35

Cannizzaro's experiment: his accepted truths

Back 35

1. molecules contain whole numbers of atoms
2. equal volumes of gases contain same # of molecules
*therefore masses of equal volumes of gases are proportional to the relative masses of the particles

**able to find RELATIVE molecular masses (relative to Hydrogen, given mass 2)

Front 36

Is Cannizzaro's application of Avogadro's hypothesis complete?

Back 36

No...a chemical formula must be known to find molecular mass; he analyzed as many compounds as possible to discover true masses

Front 37

atomic structure:

Back 37

very small, but massive positively charged nucleus surrounded by negatively charged electrons; neutrons also in nucleus

Front 38

mass of protons/neutrons/electrons

Back 38

proton and neutron have essentially same mass; electron is 1836 times smaller in mass

Front 39

Cathode ray tube:

Back 39

tube filled with a gas has voltage sent through it, separating the atoms into its subcomponents

Front 40

How does cathode ray tube work? How did it provide evidence for the electron

Back 40

magnitude of current in tube is reduced but never goes to 0, meaning current must originate from one of the plates (cathode!) to the other side; carry negative charge; these particles deflected by magnetic and electric fields: found mass to charge ratio

Front 41

Millikan's Oil Drop experiment

Back 41

discovery of the charge and mass of electron

individual oil droplets falling towards plate with (-) charge, xrays sent towards them ionizing some into + and some into - charged; (-) charged particles stopped or were repelled by plate, by balancing the plate's charge, final electron charge and mass discovered

Front 42

electron charge

Back 42

1.59x10^-19C

Front 43

electron mass

Back 43

9.11x10^-31kg

Front 44

Plum Pudding model

Back 44

jelly-like fluid with positive charge with electrons embedded in this fluid; William Thomson and JJ Thomson

Front 45

Rutheford: Nucleus

Back 45

shot alpha (+ charge) particles at thin sheet of gold foil assuming they would go straight through (based on plum pudding model); most did, but very few were deflected at high angles:

1) majority of atom empty space
2)nucleus is very small but with huge mass, + charge