Scientists and Their Discoveries Flashcards

Flashcards about key scientists and their discoveries in physics, chemistry, and biology.

Who was Johannes Kepler?

Discovered that planetary orbits are elliptical.

Who was Blaise Pascal?

Developed Pascal’s Principle, applied in hydraulic systems like hydraulic presses and dental chairs.

Who was Daniel Bernoulli?

when the velocity of a fluid increases, its pressure decreases, applied in spray devices and airplane wings.

Who was Archimedes?

Established the Principle of Buoyancy: any object submerged in a fluid

experiences an upward buoyant force equal to the weight of the displaced fluid.

Who was Christian Doppler?

Explained the —— Effect. the change in frequency of waves relative to an observer moving toward or away from the source, applied in radar and sound wave analysis.

Who was Charles-Augustin de Coulomb?

Formulated —— Law. the force between two electrical

charges is directly proportional to the product of their charges and inversely proportional to the square of their distance apart.

Who was J.J. Thomson?

Discovered the electron and measured its mass-to-charge ratio. using the cathode ray tube experiment.

Who was Robert Millikan?

Measured the charge of the electron using the oil-drop experiment.

Who was Hans Christian Ørsted?

Discovered that electric current passing through a wire creates a magnetic field around it.

Who was Michael Faraday?

Discovered electromagnetic induction, the principle behind electric generators.

Who was Wilhelm Röntgen?

Discovered X-rays.

Who was Albert Einstein?

Explained the photoelectric effect, proving that light behaves as both a particle and a wave (photon theory).

Who was Louis de Broglie?

Proposed the wave-particle duality of moving objects.

Who was Arthur Compton?

Proved the momentum of photons through the Compton Effect.

Who was Werner Heisenberg?

Formulated the Uncertainty Principle: it is impossible to simultaneously determine the exact position and velocity of an electron.

Who was Ernest Rutherford?

Discovered the atomic nucleus through the gold foil experiment

Who was Joseph von Fraunhofer?

Identified dark absorption lines in the solar spectrum.

Who was Niels Bohr?

Developed the —— model of the atom, explaining that electrons orbit the nucleus in quantize energy levels.

Who was Max Planck?

Introduced quantum theory, stating that energy is quantized and emitted in discrete packets (quanta).

Who was Heinrich Lenz?

Stated Lenz’s Law: the induced current in a conductor opposes the change in magnetic flux that produced it

Who was Democritus?

First proposed the idea of indivisible particles called atoms.

Who was Aristotle?

Believed matter was composed of four elements: earth, water, air, and fire, rejecting the concept of empty spa

Who was John Dalton?

Formulated the atomic theory, stating that matter is composed of indivisible atoms that combine to form compounds.

Who was J.J. Thomson?

Discovered the electron using the cathode ray tube experiment and proposed the plum pudding model of the atom.

Who was Wolfgang Pauli?

Formulated the —- Exclusion Principle: no two electrons in an atom can have the same set of quantum numbers.

Who was Friedrich Hund?

Proposed —— Rule: electrons occupy orbitals singly before pairing up.

Who was Robert Boyle?

Stated —- Law: the volume of a gas is inversely proportional to its pressure at constant temperature, applied in pressure coo

Who was Joseph Louis Gay-Lussac?

the pressure of a gas is directly proportional to its absolute temperature at constant volume.

Who was Amedeo Avogadro?

Defined —— Law:equal volumes of gases at the same temperature and pressure contain an equal number of molecules.

Who was Thomas Graham?

Discovered —— Law: the rate of effusion of a gas is inversely proportional to the square root of its molar mas

What does Hess's law state?

The total enthalpy change of a reaction is independent of the reaction pathway.

What does Le Châtelier’s Principle explain?

Explained how a system in equilibrium reacts to external changes to restore equilibrium.

Who was John Tyndall?

Discovered the —— Effect: the scattering of light by particles in a colloid.

Who was William Henry?

Formulated —- Law: the solubility of a gas in a liquid is directly

proportional to its pressure above the liquid at constant tem

Who was Svante Arrhenius?

Defined acids and bases: acids produce hydrogen ions (H⁺) in aqueous solutions, while bases produce hydroxide ions (OH⁻).

Who were Johannes Brønsted & Thomas Lowry?

Proposed the —- definition of acids and bases: acids donate protons (H⁺), and bases accept protons

Who was Gilbert Lewis?

Defined acids and bases as electron pair acceptors and donors.

Who was Jacques Charles?

the volume of a gas is directly proportional to its temperature at constant pressure .

Who was Carl Linnaeus?

Developed the binomial nomenclature system for naming organisms.

Who was Frederick Griffith?

First identified DNA as hereditary material.

Who Were Alfred Hershey & Martha Chase?

Proved DNA is not a protein but is the genetic material.

Who was Erwin Chargaff?

Discovered — Rule. in DNA, the amounts of adenine and thymine are equal, as are the amounts of cytosine and guanine.

Who was Ibn al-Baitar?

Wrote extensively on medicinal plants and their properties.

Who was Lorenzo Jaquesbon?

Identified the Jacobson’s organ, a sensory structure in snakes that detects scents.

Who was Hans Krebs?

Discovered the Krebs Cycle. which is crucial for cellular respiration.

Who was Gregor Mendel?

Father of genetics, established the laws of inheritance through pea plant experiments.

Who was Reginald Punnett?

Developed the Punnett Square for predicting genetic outcomes.

Who was George Huntington?

Discovered Huntington’s Disease. a neurodegenerative disorder.

Who was Oswald Avery?

Isolated and identified DNA as the genetic material.

Who was Abu Bakr Al-Razi?

Pioneered the use of surgical sutures and made significant contributions to medicine.

Who was Alexander Fleming?

Discovered penicillin. The first antibiotic

Who was William Harvey?

Discovered blood circulation in the human body

Who was Ibn al-Nafis?

Discovered pulmonary circulation of blood, contradicting Galen’s earlier theories