Unit 4 Atomic History

Question 1

Democritus

Answer 1

• Proposed the idea of atoms as the smallest undividiable particle of a substance.
• Stated that all the universe is composed of two elements: the atoms and the void in which they exist

Question 2

John Dalton

Answer 2

• Developed an “atomic theory” with spherical solid atoms based upon measurable properties of mass
  
  • Atoms make up everything and cannot be created or destroyed.
  • Atoms of an element are identical.
  • Atoms are rearranged in chemical reactions to form different substances.

Question 3

Sir William Crookes

Answer 3

• Discovered
  
  • cathode rays travel in straight lines
  • cause glass to fluoresce
  • give a negative charge to objects they strike

Question 4

J.J. Thomson

Answer 4

• Discovered/proved the electron
• Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram
• Also studied “canal rays” and found they were associated with the proton ( H+)

Question 5

Ernest Rutherford

Answer 5

• Studied radiations emitted from uranium and thorium and named them alpha and beta
• Gold Foil experiement
• Using alpha particles as atomic bullets, discovered the nucleus and established that the nucleus was
  
  • very dense
  • very small
  • positively charged
• Disproved the Plum Pudding Model (assumed that the electrons were located outside the nucleus)

Question 6

Max Planck

Answer 6

• used the idea of quanta (discrete units of energy) to explain hot glowing matter

Question 7

Hantaro Nagaoka

Answer 7

• Proposed a “Saturnian” model of the atom with flat rings of electrons revolving around a positively charged particle

Question 8

R.A. Millikan

Answer 8

• Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron.

Question 9

H.G.J. Moseley

Answer 9

• Using x-ray tubes, determined the charges on the nuclei of most atoms
• wrote “The atomic number of an element is equal to the number of protons in the nucleus”

Question 10

Niels Bohr

Answer 10

• Developed an explanation of atomic structure that underlies regularities of the periodic table of elements;
• Developed Bohr model (planetary model) - had atoms built up of sucessive orbital shells of electrons
• Proposed energy levels for electrons

Question 11

Louis de Broglie

Answer 11

• Discovered that electrons had a dual nature-similar to both particles and waves (Particle/wave duality)

Question 12

Werner Heisenberg

Answer 12

• Described atoms by means of formula connected to the frequencies of spectral lines.
• Proposed Principle of Indeterminancy (Heisenberg Uncertainty Principle) - you can not know both the position and velocity of a particle

Question 13

Erwin Schrodinger

Answer 13

• Viewed electrons as continuous clouds
• Introduced “wave mechanics” as a mathematical model of the atom

Question 14

James Chadwick

Answer 14

• Using alpha particles discovered the neutron

Question 15

s sublevel

Answer 15

Has one orbital

Present on every energy level

Question 16

p sublevel

Answer 16

3 orbitals

appears for the first time on 2nd energy level

Question 17

d sublevel

Answer 17

5 orbitals

appears for the first time on 3rd energy level

always fills after the s on the level above (4s and then 3d)

Question 18

f sublevel

Answer 18

7 orbitals

appears for the first time on 4th energy level

fills after the s orbital two energy levels above

(4f fills immediately after 6s)

Question 19

cation

Answer 19

ion with a positive charge

usually a metal ion

Question 20

anion

Answer 20

ion with a negative charge

usually a nonmetal

Question 21

speed of light

Answer 21

3.0 x 10⁸ m/s

Question 22

Planck’s constant

Answer 22

6.626 x 10^-34

Question 23

Aufbau Principle

Answer 23

Electrons are added to an atom in order of increasing energy.

Question 24

Hund’s Rule

Answer 24

One electron is added to all orbitals within a sublevel before a second electron is added to any orbital.

Question 25

Pauli Exclusion Principle

Answer 25

Two electrons occupying the same orbital must have opposite spins.

Question 26

Mass of proton

Answer 26

1 amu

Question 27

Mass of neutron

Answer 27

1 amu

Question 28

Mass of electron

Answer 28

0 amu

Question 29

Charge of Proton

Answer 29

+1

Question 30

Charge of electron

Answer 30

-1

Question 31

Charge of neutron

Answer 31

0

Question 32

Location of protons

Answer 32

Nucleus

Question 33

Location of Neutrons

Answer 33

Nucleus

Question 34

Location of Electrons

Answer 34

Electron cloud or Energy Levels or Orbits

Question 35

Protons determine \_\_\_\_\_\_\_\_\_\_

Answer 35

identity of the element

Question 36

Neutrons determine \_\_\_\_\_\_\_\_

Answer 36

which isotope of the element.

Question 37

Electrons determine \_\_\_\_\_\_\_\_\_\_

Answer 37

the charge (the ion of the element)

Question 38

First quantum number | (Principal quantum number)

Answer 38

n, describes the energy level the electron is on

Question 39

Second quantum number | (angular quantum number)

Answer 39

Describes the shape of the orbital (s, p, d, f)

Question 40

Allowed third quantum numbers for s

Answer 40

0

Question 41

Allowed third quantum numbers for p

Answer 41

-1, 0, +1

Question 42

Allowed third quantum numbers for d

Answer 42

-2, -1, 0, 1, 2

Question 43

Allowed third quantum numbers for f

Answer 43

-3, -2, -1, 0, +1, +2, +3

Question 44

Third quantum number

Answer 44

Describes the orientation of the orbital within the sublevel (which blank)

Question 45

Second quantum number values for each sublevel

Answer 45

s = 0 p = 1 d = 2 f = 3

Question 46

Fourth quantum number

Answer 46

describes spin of an electron First electron in orbital (blank) = +1/2 Second electron in orbail (blank) = -1/2