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Chem 16 > Atomic Theory of Matter > Flashcards

Atomic Theory of Matter Flashcards

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1
Q

what is dalton’s atomic theory

4

A
  1. element= made of atoms
  2. atoms of same element=same; atoms of different element=different
  3. atoms cannot be created/destroyed; element cannot change to another element
  4. compunds=more than 1 element combine; same relative number & kind of atoms (balancing eq)
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2
Q

important laws in the atomic theory of matter

3

A

law of conservation of mass (antoine lavoisier)
law of definitie composition (joseph louis proust)
law of multiple proportions (john dalton)

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3
Q

what is the law of conservation of mass

3

A
  • by antoine lavoisier
  • matter is not created nor destroyed during chem/physical reactions
  • total mass of reactants=total mass of products
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4
Q

what is the law of definite composition

2

A
  • by joseph louis proust
  • given compound has elements in constant composition and proportion (limiting & excess reactants)
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5
Q

what is the law of multiple proportions

A

if two elements form more than 1 compound, masses of A & B are in ratio of small whole numbers (NO, NO2, N2O, N2O2,N2O5)

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6
Q

what is the electron

A

by JJ Thompson in 1897 using cathode ray tubes (initially called corpuscules)

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7
Q

what is the cathode ray expeiment

3

A
  • cathode rays= beams that travel from - to + electrode
  • if near electric field, ray was repelled by the negative pole and it was deflected towards the positive pole=cathode ray is negatively charged (- and - repel)
  • used this & adjusted electrical field strength for beam to travel undeflected; charge-to-mass ratio of electron=-1.76 x 108 C g-1
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8
Q

what is radioactivity

2

A
  • by ernest rutherford
  • 3 types of radiation: alpha(+), beta(-), gamma(neutral)
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9
Q

what is electron’s charge

A
  • by Robert Milikan thru Milikan’s Oil Experiment
  • 1909= charge of electron is 1.602x10 -19 C thru JJ Thompson’s charge-to-mass ratio of -1.76 x10 8 C g-1
  • electron mass=9.10 x 10 -28
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10
Q

what is the Milikan’s Oil Drop Experiment

2

A
  • oil droplets with net negative charge thru xray irradiation pass thru electrically charged plates which can slow down/speed up the fall of particles when voltage is varied depending on distance between droplets
  • calculated from oil droplets that the charge is 1.602 x 10 -19 C
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11
Q

what is radioactivity

3

A
  • by henri becquerel in 1896
  • uranium spontaneously emits radiation (radioactivity)
  • marie & pierre curie started to identify and isolate source of radiation of uranium
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12
Q

who is william ramsay

A
  • 1894, found argon in atmosphere
  • found helium (1895), neon (1898), krypton (1898) and xenon (1898)
  • won noble peace prize in chemistry
  • died due to radioactivity
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13
Q

who is JJ Thompson

3

A
  • discovered electrons (called them corpuscules)
  • plum pudding model (- charge scattered around positive charge)
  • started separating neon isotopes by mass leading to techniques of mass spectrometry
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14
Q

who is marie curie

4

A
  • investigated radioactive substances with pierre curie, husband
  • discovered radium & polonium
  • 2 nobel prizes (physics & chemistry)
  • unit curie=radioactivity
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15
Q

what is the plum pudding model

2

A
  • by JJ thompson (early 1900s)
  • atom is a + charged evenly distributed sphere/cloud w/ dispersed- charged e-
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16
Q

what is the nuclear model of an atom

3

A
  • by ernest rutherford thru his gold foil experiment
  • discovered nucleus & proton
  • also by james chadwick who found neutrons
17
Q

what is rutherford’s gold foil experiment

5

A
  • if plum pudding, laser (+ charged, ALPHA) from gold foil should go straight bec. sphere is full of negative charges (attract)
  • real result: some laser bounced from the gold foil and some went straight (bounced=repelled; straight=attract); concentrated + charge at center of atom=nucleus
  • nucleus = positive charge and mass of the atom
  • The rest of the atom is primarily empty space.
  • tiny electrons surrounding + charged nucleus = neutral charge
18
Q

what are neutrons

A

neutral particles in nucleus & has similar mass with protons

19
Q

what is the electric charge & atomic charge of a proton

A

+1.602 x 10 -19 C
+1

20
Q

what is the electric charge & atomic charge of a neutron

A

0
0

21
Q

what is the electric charge & atomic charge of a electron

A

-1.602 x 10 -19
-1

22
Q

what is the mass and atomic mass of a proton

A

1.6726 x 10 -24
1.0073

23
Q

what is the mass and atomic mass of a neutron

A

1.6749 x 10 -24
1.0087

24
Q

what is the mass and atomic mass of an electron

A

9.1094 x 10 -28
0.00054858

25
Q

what is atomic no.

A

AXZ ∆

Z

number of protons; atomic number; characteristic of element

26
Q

what is mass number

A

AXZ ∆

A

protons + neutrons
says isotopic nature

27
Q

what is a net charge

A

AXZ ∆ ^ #±

± = net charge
protons-electrons

28
Q

what are ions

A

AXZ ∆ ^ #±

charged particles when an atom loses or gains electrons

29
Q

what are anions

A

(-) charged ion (gain electron)

30
Q

what are cations

A

(+) charged ions (loss of electrons)

31
Q

what is an isotope

3

A
  • same element, same chem properties, different radioactive properties & weights
  • atoms have identical outsides but different insides (different neutrons)
  • by frederick soddy (noble prize in chemistry in 1913)
32
Q

how to get ave. atomic mass

3

A
  1. % to decimal
  2. multiply to isotope atomic mass
  3. get ave.
33
Q

what word did atom come from

A

atomos “indivisible”

by democritus & leucippus

34
Q

what is bohr’s model

think of solar system

A
  • electrons moved around nucleus in orbits of fixed sizes and energies
  • quantisized electron energy (definite energy level per orbit; KLMN in to out; n=1,2,3,4, etc)
  • did not work for heavier atoms
  • postulated: only special orbits called discrete orbits of electrons are allowed inside atom & electrons do not radiate energy as they revolve (because normally, when an electron moves in a circular motion, it gains energy but it will collapse to the nucleus making it unstable)
35
Q

what is the brownian motion

A

when robert brown in 1827 placed pollen into water and looked at it thru a microscope and saw the pollens just jiggling = liquid atoms and pollens jiggle jiggle & einstein found the size of an atom

Chem 16 (3 decks)

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