Atom Flashcards
John Dalton- which theory?
put together many observations and results of numerous experiments made by other scientists and formulated the atomic theory.
Law of Conservation of Mass
(3)
“Atoms cannot be created or destroyed (postulate 1) or
converted into other types of atoms. (postulate 2)
since every atom has a fixed mass, (postulate 3) during a chemical reaction atoms are combined differently and therefore there is no mass change overall.”
Law of conservation of mass
Still has components of bothhhhh?????!????
matter as being composed of
small, indivisible
particles called atoms
atoms are like billiard balls, which are thought
to be
solid and indestructible ..dalton
they are in constant motion and collide with one
another, causing
changes in their motion and
resulting in chemical reactions
The billard ball model assumed that atoms were ?
indestructible, which was later disproved by the discovery of nuclear reactions, which can break atoms apart or merge them together to create new elements.
o The model did not account for the existence of ?, which were later discovered by scientists such as J.J. Thomson and Ernest Rutherford
of subatomic particles- electrons, protons, and neutrons,
did not explain the internal structure of atoms, which was later revealed by more advanced theories such as the atomic models of Niels Bohr and Erwin Schrödinger.
Billard ball
o The model did not account for the existence of isotopes- that are atoms of the same element but they have a different number of neutrons in their nuclei.
Billard ball
- Limitations of Dalton’s Model
- assumed that atoms were indestructible,
- did not account for the existence of subatomic particles- electrons, protons, and neutrons,
- did not explain the internal structure of atoms
- did not account for the existence of isotopes
- did not have any concept of chemical bonding, which is the way atoms combine to form molecules
- did not explain the phenomenon of atomic spectra, which was observed in light emitted or absorbed by atoms.
o He was able to explain some previously unexplained phenomena, such as the fact that atoms are electrically neutral, and that the ratio of the charge of an electron to its mass is the same for all elements.
J.J THOMSON
? discovered the electron, a subatomic particle while conducting experiments on ?
Thomson, cathode rays.
Thomson’s Plum
Pudding Modelsyays that?
Thomson’s Plum
o atoms are neutral because the negative charges of the electrons were balanced out by an equal amount of positive charge in the “soup” or “pudding”
Thomson’s Plum
Pudding Model weaknesses
did not account for the existence of the nucleus
could not explain the stability of atoms
ERNEST RUTHERFORD
proposed that atoms were composed of a small, dense, positively charged nucleus at the center, surrounded by negatively charged electrons that orbited around it like planets around the sun. ERNEST RUTHERFORD (1 ERNEST RUTHERFORD
The nucleus contains protons and neutrons, and the number of protons in the nucleus determines the element who?
ERNEST RUTHERFORD (
Discovered a particles where helium atom with their electrons are removed
Radioactivity
Model of an deho: atoms were composed of a small, dense, positively charged nucleus at the center, surrounded by negatively charged electrons that orbited around it like planets around the sun
Rutherford’s Planetary Model
Rutherford’s Planetary Model weakness
did not account for the fact that electrons move in multiple orbits around the nucleus
Niels bohr
NIELS BOHR proposed an early model of the atom as a central nucleus containing protons and neutrons being orbited by electrons in shells or energy levels
electrons orbit the nucleus in specific, discrete orbits, or “energy levels”, and that the energy of an electron is determined by its orbit
NIELS BOHR
these energy levels are designated by a number and the symbol “n“
Bohr’s Atomic Model