History of the Atom
John Dalton
(1808) looked at how gases combine chemically; looked at ratios of how elements combine to form compounds (stoichimetry); saw that elements always combined in whole number ratios to form compounds; supported idea of atom; billiard ball model said 1) all matter is made of indestructible atoms, 2) all atoms of an element are identical, 3) atoms of different elements have unique properties, 4)atoms combine to make larger compounds
Ernest Rutherford
(1909) showed that atoms are mostly free space, 1st proof of protons in a nucleus, electrons are outside nucleus in space; played with radioactivity and shot alpha particles at Au (Au Foil Experiment, foil fluorescent screen lights up when alpha particles hit it)
Democritis
(c. 450 BCE) came up with "atomos" (uncuttable); all matter made of small particles that were indivisible
john dalton
1802
John Dalton
1808 - gathered evidence favoring Democritus' theory. Proposed an Atomic Theory. 1) Every element is made of tiny, unique particles called atoms that cannot that cannot be subdivided. 2) Atoms of the same element are exactly alike. 3) Atoms of different elements can join to form molecules.
john dalton
1808-1810
j.j. thomson
1897
JJ Thompson
1897 - Discovered 1st component of atom (the electron) through his cathode ray experiment. His model "the plum pudding model" saw an atom as a ball of positively charged stuff with electrons scattered throughout.
albert einstein
1905
robert millikan
1909-1911
ernest rutherford
1910
Ernest Rutherford
1912 - Discovered through his gold foil experiment that the atom was mostly empty space. Positive charge is in center of atom (nucleus). Electrons circle nucleus like planetary obits.
niels bohr
1913
Niels Bohr
1913 - His model has a nucleus, but the electrons have certain energy levels which determine their path around the nucleus. Electrons cannot be found in between energy levels.
james chadwick
1932
James Chadwick
1932 - Discovered the neutron.
Democritus
400 BC - All matter is composed of tiny, invisible, and indivisible particles in motion. He called these particles atoms.
democritus
5th century BC
Neutron
A particle with no charge found in the nucleus
Atom
Basic unit of matter
Nucleus
Center of an atom that contains both protons and neutrons
J.J. Thomson
Discovered negatively charge particle called electrons; Describe the atom as blueberry muffin, chocolate chips in a cookie where the blueberries and chips were the electrons.
Niels Bohr
Discovered that electrons move around the nucleus in orbitals
Proton
Found in the nucleus of an atom and has a positive charge
Ernest Rutherford
Found that atom had a densely packed, POSITIVELY, charged center in the atom, called the NUCLEUS;
Democritus
Gave us the word "atom"
Bohr
I am a physicist that correctly predicted the frequencies of the lines in hydrogen's atomic spectrum and my model was used up until recently.
Chadwick
I am a physicist that discovered the neutron.
Rutherford
I am a scientist that used gold fold in an experiment to refine the concept of the nucleus.
Democritus
I am the Greek philosopher that said "Matter is composed of empty space through which atoms move."
Thomson
I am the scientist that made a model of the atom that was a spherical particle with uniformly distributed positively charged fluid with negatively charge particles located in the fluid.
Chadwick
I described isotopes.
Dalton
I developed the Billiard Ball model of the atom.
Rutherford
I developed the Nuclear model of the atom.
Bohr
I developed the Planetary model of the atom.
Thomson
I developed the Plum Pudding model of the atom.
Rutherford
I developed the first atomic model that contained empty space separating the nucleus from the electrons.
Democritus
I made the first model of the atom that was based on no scientific evidence.
Dalton
I made the first model of the atom that was based on scientific observations and experimentation.
Democritus
I said "The universe was made of empty space and tiny bits of stuff called atoms."
Bohr
I used my atomic model to explain atomic spectra.
Rutherford
I was the first to discover the positively charged nucleus at tthe center of the atom.
Thomson
I was the first to state that atoms can be divided into smaller particles.
Democritus
I was the first to state that atoms were indivisible particles of matter.
Bohr
My model of the atom arranged electrons in definite paths associated with energy levels around the nucleus.
Bohr
My model of the atom described how electron jump between levels by absorbing energy or emitting photons of light at a particular wavelength.
Thomson
My model of the atom described the atom as a sphere of positive electrical charge in which electrons are embedded.
Dalton
My model of the atom made the first attempt to explain the properties of matter due to differences in atoms.
Bohr
My model of the atom only explained the arrangement of electrons in hydrogen atoms.
Dalton
My model of the atom stated that atoms are indivisible and alike for each element, but different for different elements.
Dalton
My model of the atom stated that compounds consist of atoms of different elements.
Bohr
My model of the atom stated that the electrons move in circular orbits around the nucleus.
Rutherford
My model of the atom stated that the nucleus contained protons.
Dalton
My model of the atom was the first to state that elements are composed of atoms.
Electron
Negatively charged particles that orbit the nucleus
Atomic Mass
The number of protons AND neutrons
Atomic Number
The number of protons in an atom
Plum pudding model
Thompson; atoms are blobs of positive charge studded with electrons
j.j. thomson
an english physicist who worked with cathode ray tubes (CRTs) and was credited with the discovery of the electron.
niels bohr
attempted to explain the position of electrons.
Billiard Ball Model
by John Dalton; round atoms with no distinguishing characteristics
j.j. thomson
came up with the plum-pudding model, or the raisin bun model, which consisted of electrons and positively-charged "goo."
ernest rutherford
created an atomic model that consisted of electrons, empty space, and a nucleus made of positively-charged protons.
niels bohr
created an atomic model that only worked with the element hydrogen.
John Dalton
described the atom as a solid sphere
john dalton
developed the theory of the atom, which was a revival of democritus' "smallest piece of matter."
j.j. thomson
discovered that there were mysterious negatively-charged particles that came from the cathode end that were being deflected by magnetic and electric fields. they were very small and had a negative charge and came to be called electrons and were assumed to be a part of all matter.
niels bohr
experimented with the wavelengths of light given off by excited hydrogen atoms.
Chadwick
found neutrons
john dalton
known as the father of modern chemistry who was also an english school teacher who began teaching math and chemistry at the age of twelve.
ernest rutherford
proposed the presence of the nucleus.
james chadwick
proved the existence of the neutron
Niels Bohr
said electrons are in orbits with energy levels around the nucleus (however this only works with H); Planetary Model; played with gas discharge model
aristotle
said matter is infinitely divisible, and that no matter how small a piece is, it can always be divided into smaller pieces.
john dalton's atomic model
said that all matter is made up of tiny, indivisible, and indestructible particles called atoms, atoms of the same element are identical, atoms of different elements differ in soe fundamental way, and that atoms combine in simple, whole number ratios to form compounds.
democritus
said that there exists a "smallest piece of matter," which cannot be divided any further. called them atoms.
J.J. Thompson
showed existence of electrons; played with Cathode Ray Tubes (vacuum tubes filled with a gas); applied electric field and saw a stream of particles (electrons) move towards positive end; plum pudding model
niels bohr
tracked the electrons in orbits.
niels bohr
used rutherford's model and his own experiments with hydrogen to develop his model of the atom.
ernest rutherford
was an expert on radiation who performed the gold foil experiment with assistants geiger and marsden.
john dalton
worked with mixtures of gases and determined how pressure was related to their proportions and listed all the known elements from lightest to heaviest.
