John Dalton what is he known for?

Question

Also what was his key roles that chemist still use in science today?

Answer 1

All of the above are correct. He was mainly known for the Modern Atomic Theory which is logically necessary because of the three basic laws of chemistry:

1. Law of Conservation of Mass in a Chemical Reaction by Antoine Lavoisier
2. Law of Definite Proportions by Joseph Proust
3. Law of Multiple Proportions by John Dalton

A minor note. Dalton is also know for Daltonism, or "Color Blindness". John was color blind in only ONE eye. So he could see normal colors in on eye and he could see what color blind people see in the other eye. After his death his eyes were disected.

Answer 2

John Dalton published his atomic theory in 1803. He also published the Law of Multiple Proportions in that year. We also study Dalton's Law of Partial Pressures which deals with the partial pressures of a combination of gases in a sealed container.

Answer 3

matter is composed of atoms.
Put together the first atomic theory in 1803.

Dalton's theory had four main concepts:

1. All matter is composed of indivisible particles called atoms. Bernoulli, Dalton, and others pictured atoms as tiny billiard-ball-like particles in various states of motion. While this concept is useful to help us understand atoms, it is not correct as we will see in later modules on atomic theory linked to at the bottom of this module.
2. All atoms of a given element are identical; atoms of different elements have different properties. Dalton’s theory suggested that every single atom of an element such as oxygen is identical to every other oxygen atom; furthermore, atoms of different elements, such as oxygen and mercury, are different from each other. Dalton characterized elements according to their atomic weight; however, when isotopes of elements were discovered in the late 1800s this concept changed.
3. Chemical reactions involve the combination of atoms, not the destruction of atoms. Atoms are indestructible and unchangeable, so compounds, such as water and mercury calx, are formed when one atom chemically combines with other atoms. This was an extremely advanced concept for its time; while Dalton’s theory implied that atoms bonded together, it would be more than 100 years before scientists began to explain the concept of chemical bonding.
4. When elements react to form compounds, they react in defined, whole-number ratios. The experiments that Dalton and others performed showed that reactions are not random events; they proceed according to precise and well-defined formulas.

Answer 4

the measurement unit (Dalton) equal to the mass of one proton/neutron. Proteins etc. are measured in kilodaltons.