How long were the eastern woodlands summers?

Answer 1

Democritus 400 B.C.

He was the first person to use the term atom.He stated that all matter is made up of tiny indivisible particles called atoms.He said atoms could be of different colors, sizes, and shapes but they could not be broken into smaller particles and therefore were indivisible.

Antoine Lavoisier-

0 1782

Experimented with metal and rust. He sealed and iron nail into a box. He massed the box, heated the box, re-massed the box (mass before was the same as the mass after), and removed the nail. The nail became rusty and was greater in mass. This showed that the new mass on the nail was from matter in the box and was not simply created. Lavoisier wrote the Law of Conservation of Matter. This states that "matter is neither created or destroyed during a chemical reaction. The atoms are simply rearranged."

Joseph Proust

0 1810

Took samples of green copper roofs from all over Europe. He analysed the samples and found that all the samples broke down to one part copper, one part carbon, and three parts oxygen. From this data he wrote the law of definite proportions this states that a compound will always break apart into the same whole number ratios no matter where it is found or how much is present.

John Dalton

0 1826

1826- John Dalton- analyzed other chemists work and compiled into a document he called Daltons atomic theory. He stated 4 basic postulates about matter.

- all matter is made of atoms

- atoms are indestructible and cannot be broken into smaller parts.

- atoms of an element are alike in size and mass.

- atoms of different elements differ in size and mass.

- atoms combine in whole numbers ratios to form compounds during a chemical reaction bonds are broken, atoms are rearranged into new compounds and new bounds form, nothing is lost or gained.

Ernest Rutherford

0 1909

1909- Ernest Rutherford- Had his associates perform the Gold Foil Experiment. They shot positively charged the alpha particles at gold foil pressed to a thickness of just 2 atoms. Almost all of the particles went directly through the foil. 1 out of 8,000 particles were deflected and had a curved path. 1 out of 40,000 alpha particles were deflected back to the source of the particles. Rutherford discovered the nucleus.

Neils Bohr

0 1922

1922-Neils Bohr- experimented with elements sealed in glass tubes. He electrified the elements and discovered that each element fluoressed a different color. He then passed the light through a prism and was surprised that a complete spectrum of color did not form. Instead he saw distinct bands of colored light. He hypothesized that the bands of light were from specific orbits of electrons around the nucleus of the atom. He created the planetary model. He thought the nucleus was in the center like the sun is in the solar system and he thought the electrons were in specific orbits the way the planets are in orbit to the sun.

Schrodinger

0 1926

preformed mathematical calculations and determined Bohr's planetary model was not correct. He determined that electrons could be within the energy levels and that their energy predicted where they were likely to be found he said it was impossible, due to their rapid wave like motion, to predict exactly where an electron is located in any moment of time. He made a model of the atom that is called the electron cloud model is a sphere of dots. Each dot represents a possible location of an electron.

James chadwick

0 1932

performed an experiment using beryllium foil. He shot alpha partials at the foil and was able to break apart the nuclei of the atoms. By doing this he discovered neutrons. Neutrons are the second nuclear partial in an atom they are neutral having no electric charge.

Gell-Mann and Zweig

0 1954

Gell-Mann and Zweig, preformed thousands of trials where they sent a spray of electrons at metal foils the electrons passed through the foil and struck photographic paper. They developed and enlarged the pictures and hypothesized that protons and neutrons were made of smaller particles called Quarks. In 1964, they confirmed that protons are made of three quarks 2 up quarks and 1 down quark. Neutrons are made of 3 quarks 2 down and 1 up. They also determined that an up quark has a charge of 2/3 a down quark has a charge of -1/3.

The Modern Standard Model

0 1978

The Modern Standard Model became the accepted model of the atom. It combines the Electron Cloud Model and our new understanding of the quarks into one model.

Demo1

0 2008