M1U1 Timeline Flashcards
Enumerate the 7 Atomic Theories and its dates
- Atomism (442 BC)
- Aristotle Model (300 BC - Early 1800s)
- Solid Sphere Model (1803)
Hook and Eye Affair Model (1803) - Plum Pudding Model (Late 1890)
- Nuclear Model (1911)
- Miniature Solar System/ Planetary Model (1913)
- Modern Atomic Theory: Quantum Mechanical Model (1926)
When and who discovered electrons?
1897, Joseph John Thomson
When and who discovered protons?
1919, Ernerst Rutherford
When and who discoveerd neutrons?
1932, James Chadwick
Who were the ones to propose Atomism?
ancient Greek philosopher Democritus and Leucippus
What does the theory of Atomism state?
All matter is composed of indivisible elements called atoms.
Wha tare atoms according to democritus?
Atoms were small, hard particles made of the same materials, but formed into different shapes and sizes
According to Aristotle Model, what was the four elements/ substance of matter?
Fire, Air, Water, Earth
According to Aristotle Model, what was the four properties/ essences of matter?
Hot, Cold, Dry, Wet
He proposed a model as an attempt to describe the structure of the atom?
John Dalton
What was John Dalton’s profession when he proposed a theory in 1803?
an English school teacher
How are atoms described according to the Solid Sphere Model?
Atoms are tiny, indesctructible spheres with no internal structure
It is a theory that matter is simply composed of atoms of different weights and is combined in ratios by weight. It is also proposed that these atoms are spherical and are in motion
Solid Sphere Model
Describe the Hook and Eye Affair Model
Matter is made of tiny particles which is imagined to be little balls that are arranged in different combinations to make different things.
What became the basis for television?
a primitive cathode ray tube
When and who constructed a primitive cathode ray tube?
1870, Sir William Crookes
When and who theorized that radioactive particles cause atoms to break down whihc then releases radiation?
1898, Pierre and Marie Curie
What did Pierre and Marie Curie theorized?
Radioactive particles cause atoms to breakdown, releasing radiation that takes the form of energy and subatomic particles.
Describe the atom as proposed by the Plum Pudding Model
the atom is composed of a positively charged sphere with negatively charged electrons distributed throughout it
Who proposed the Plum Pudding Model?
Joseph John Thomson
Why is it said that atoms are electrically neutral?
Because the positive and negative charges together would balance the two things so that the atom would become electrically neutral
When and who discovered the quantum theory?
1900, Max Planck
What does the quantum theory state?
Electromagnetic energy could only be emitted in quantized form
Plank’s quanta are now called what by physicists?
Photons
How was electrons discovered?
Using properties of Cathode rays
Together with JJ Thomson, he discovered that there must be some positive charge somewhere
William Thomson
When and who created special and general theories of relativity, and hypothesized the particle nature of light?`
1905, Albert Einstein
This measures the charge of a single electron and is one of the fundamental physical constants.
elementary charge
When and who measured the charge of a single electron?
1908, Robert Millikan
elementary charge = ?
1.602 x 10^(-19)
He developed the theory for the structure of the atom
Ernest Rutherford
What was Ernest Rutherford known as?
Father of Nuclear Physics
What does the nuclear model propose?
Proposed that most of the mass of the atom is contcentrated in tiny, positively charged nucleus at the center, with negatively charged electrons around it.
Using this experiment, Rutherford observed the scattering of alpha particles and demonstrated for the first time, the existence of the atomic nucleus
gold foil experiment
What is a nucleus according to Ernest Rutherford?
It is the small, dense, positively charged center of an atom
Developed the Miniature Solar System/ Planetary Model in 1913
Niels Bohr
What was Bohr’s atomic model about?
Electrons travel in orbits around the nucleus, and chemical properties are determined by how many electrons are in the outer orbits
Bohrs also integrated Planck quantum theory which states that —
when an electron changes orbit, it emits a quantum of discrete energy
What did Rutherford’s scintillation detector detected when a beam of alpha particles was shot into air?
Hydrogen nuclei
Aside from Rutherford, who was credited for the discovery of protons?
Eugene Goldstein
Who and what what discovered in 1926?
Erwin Schrödinger, Modern Atomic Theory: Quantum Mechanical Model
What are the two other terms for Erwin Schrödinger’s Modern Atomic Theory: Quantum Mechanical Model
Quantum Chrynodynamics
Electron Cloud Model
What was Schrödinger’s finding?
Electrons do not orbit but move at high speeds in an electron cloud around the nucleus.
What does electrons do in an electron cloud according to Schrödinger?
In an electron cloud, electrons whirl around a billion times in one second in a random pattern.
What component of the atomic nucleus was discovered in 1932?
Neutron component
The discovery of netron explained what?
nuclear fission of uranium 235; this also made it possible to produce elements heacier than uranium in the lab
When and who discovered the nuclear fission?
Otto Hahn and Lise Meitner
What was Otto Hahn regearded as?
Father of Nuclear Chemistry
What were discovered in 1951?
Glenn Seaborg discovered:
- transuranium elements
- advances in nuclear medicine including develoopment of I-131 for thyroid disease
When and who proposed the quark model?
1964, Mann
What does the quark model describe?
Describes elementary particles that have no substructure (and therefore can’t be split)
These three along with many other scientists said that electrons do not orbit the nucleus in neat planet-like orbits but move at high speeds in an electron cloud around the nucleus. (1926- 20th Century)
Schrodinger, Heisenberg, Einstein
People under the medieval period
Democritus
Leucippus
Aristotle/Empodecles
