The Atomic Theory

Question 1

Theory/Law?

It states that pure compound is made up of elements in the same proportion by mass.

Answer 1

Law of Definite Proportions

under Joseph Louis Proust

Question 2

Theory/Law?

Two elements combine to form more than one compound - ratio of the mass of an element to a fixed mass of the other element is a whole number/simplest fraction.

Answer 2

Law of Multiple Proportions

under John Dalton

Question 3

Who?

Elements are composed of tiny indivisible particles called atoms.

Answer 3

John Dalton

English chemist, mathematician, and philosopher

Question 4

Theory/Law?

Chemical reaction involves separation, combination, and rearrangement of atoms only.

Answer 4

Law of Conservation of Mass

under John Dalton

Question 5

Theory/Law?

Atoms of different elements are chemically different; atoms of a given element are of the same size, shape, mass, and chemical properties.

Answer 5

Dalton’s Atomic Theory

by John Dalton

Question 6

Who?

Determined the ratio of electric charge to the mass of an electron to be -1.76x10^(8) coul/gram.

Answer 6

Joseph John Thomson

British physicist, recepient of Nobel Prize in Physics (1906)

Question 7

Model?

Well-known gold foil model experiment where most alpha partcles went through the foil; few were deflected.

Answer 7

Rutheford’s Nuclear Model (1911)

by Ernest Rutherford

Question 8

Who?

Discovered radioactivity in uranium

Answer 8

Antoine Henri Becquerel

French physicist

Recepient of Nobel Prize in Physics (1903)

Question 9

Model?

Model proposed by John Dalton

proposing all matter is composed of atoms

Answer 9

Dalton’s Billiard Ball Model

(1803)

Question 10

Who?

Proposed that most atom is an empty space, and positive charge of an atom (proton) is concentrated in nucleus.

Answer 10

Ernest Rutherford

New Zealand chemist, recipient of Nobel Prize in Chemistry (1908)

Proponent of the Proton and the Nucleus

Question 11

Who?

Discovered neutron by bombarding a beryllium atom with alpha particles

Answer 11

James Chadwick

British physicist, Nobel Prize in Physics recipient (1935)

Question 12

Who?

Determined the charge of neutron

Charge: -1.60 x 10^(-19)

Answer 12

Robert Andrews Milikan

American physicist, Nobel Prize in Physics recipient (1923)

Question 13

Atoms that have the same atomic number but different number of mass/neutrons.

Answer 13

Isotopes

Question 14

Principle?

Most stable arrangement of electrons in subshells is the one with more parallel spins.

Answer 14

Hund’s Rule of Multiplicity

Proponent: Frederick Hund

Question 15

Weighted average of the atomic masses of the isotopes based on their percentage abundance.

Answer 15

Average atomic mass

Question 16

Who?

Discovered radioactivity in uranium and pollonium.

Answer 16

Marya Skolodowska Curie

Polish chemist/physicist, Nobel Prize Physics (1903), Chemistry (1911)

She also coined the word “radioactivity”

Question 17

Principle?

No two electrons in an atom can have the same set of quantum numbers and an atomic orbital must contain max. of two electrons with opposite spins.

Answer 17

Pauli’s Exclusion Principle

Proponent: Wolfgang Pauli

Question 18

Who?

Discovered the X-rays

Answer 18

Wilhelm Konrad Roentgen

Nobel Prize in Physics

(1901)