Historical chemist Flashcards
Chemist timeline:
- Democritus- 400 B.C
- Aristotle-350 B.C
- Andreas Libau- 1597
- Robert Boyle-1600s
- Antoine Laurent Lavoisier-1770s
- John Dalton-1808
- J.J. Thomson-1898
- Hantaro Nagaoka- 1904
- Ernest Rutherford-1911
- Niels Bohr-1913
- James Chadwick-1932
People with the atomic theory through the years:
- Democritus- 400 B.C
- Robert Boyle-1600s
- John Dalton-1808
- J.J. Thomson-1898
- Hantaro Nagaoka- 1904
- Ernest Rutherford-1911
- Niels Bohr-1913
- James Chadwick-1932
In about 400 B.C., What did the Greek philosopher Democritus
-Democritus used the word “atomos” to describe the smallest particles that could not be broken further.
(atomos means invisible)
-Democritus stated that each type of material was made up of a different type of atomos. These different particles gave each material its own unique set of properties.
-By mixing different atomos, you could make new materials with their own unique properties.
about 350 B.C. what did the Greek philosopher, Aristotle support?
He stated that everything was made of earth, air, fire, and water
his description of the matter was preferred over Democritus’s description for 2000 years.
What did the German alchemist Andreas Libau do?
the German alchemist Andreas Libau published Alchemia, a book describing the achievements of alchemists
Libau also explained how to prepare chemicals such as hydrochloric acid. This type of information made his book the first chemistry text ever printed.
What did Robert Boyle do? (4)
In the 1660s, Robert Boyle(an Irish aristocate) experimented with the behavior of gases.
- He was interested in what happened when gases were placed under pressure.
- He was also interested in determining the composition of gases and other substances
Through his experiments and observations, Boyle
became convinced that matter was made up of tiny particles, just as Democritus had suggested in about 400 B.C.
the tiny particles, existing in would group together in different ways to form individual substances.
What did Antoine Laurent Lavoisier do? (4)
- studied chemical interactions.
developed a system for naming chemicals. - made it easier to compare the results of their experiments
Described substances such as hydrogen, oxygen, and carbon
Lavoisier is called the “father of modern chemistry.”
supported the losing side during the French Revolution and was executed
Lavoisier’s wife, Marie, continued his work.
What did John Dalton do? (4)
-put forward the first modern theory of atomic structure
He stated that each element is composed of a particle called an atom.
Dalton’s model is sometimes called the “billiard ball model” because he thought of the tiny atoms as solid spheres.
. He was the first to define an element as a pure substance that contained no other substances. Gold, oxygen, and chlorine are examples.
All atoms in a particular element, he said, are identical in mass, and no two elements have atoms of the same mass.
What did British physicist J.J. Thomson do?
- He is credited with being the first person to discover a subatomic particle (a particle smaller than an atom)
- He named them electrons
- -Thomson proposed what is called the “raisin bun model” of the atom.
- -He described the atom as a positively charged sphere in which negatively charged electrons were embedded like raisins in a bun
- -The negative electrons balance the positive sphere, so the whole atom has no electrical charge.
What did Japanese physicist Hantaro Nagaoka do?
In his model, the atom resembled a miniature solar
system
At the center of the atom was a large positive charge.
The negatively charged electrons orbited around this charge like planets orbiting around the Sun
What did British scientist Ernest Rutherford do?
He suggested that atoms were mainly empty space through which the positive particles could pass, but at the core was a tiny positively charged center. This he called the nucleus
. He also calculated that the nucleus was only about
1/10 000th the size of the atom
What did Danish Researcher Neil Bohr do?
- suggested that electrons do not orbit randomly in an atom
- Bohr said that they move in specific circular orbits or electron shells
- He believed that electrons jump between these shells by gaining or losing energy
What did the British physicist James Chadwick do?
-Chadwick discovered that the nucleus contained positively charged particles called protons, and neutral particles called neutrons.
The neutron has about the same mass as the proton but carries no electrical charge. An electron has only 1/1837th the mass of either a proton or a neutron.
Today, most people still use the Bohr model to describe the particles that make up the atom
Today’s Model
The quantum mechanical model of the atom describes
electrons as existing in a charged cloud around the nucleus,
