Dalton's Atomic Theory Flashcards
According to law of mass
conservation: the total mass of substances does not change during a chemical reaction. What does it mean?
The number of substances may change and, by definition, their properties
must, but the total amount of matter remains constant. This means that atoms are neither created nor destroyed
State the law of mass conservation
The total mass (of substances) remains constant during a chemical reaction
According to the law of definite
(or constant) composition, no matter what its source, a particular * is composed of the same * in the same * by mass.
compound, elements, parts ((fractions))
State the law of definite composition
Any sample of a given compound has the same elements present in the same parts by mass
law of multiple proportions:
if elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as *
a ratio of small whole numbers.
State the law of multiple proportions
in different compounds of the same
elements, the masses of one element that combine with a fixed mass of the other
can be expressed as a ratio of small whole numbers.
Who proposed the law of mass conservation?
Antoine Lavoisier
Dalton’s atomic theory
1. All matter consists of atoms, tiny indivisible particles
pass
- All atoms of a given element are the identical but different from atoms of all other elements
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- Atoms of one element cannot be converted to atoms of another element
atoms of the original substances recombine to form different substances and thus atoms are neither created nor destroyed in a chemical reaction.
- Compounds result from the chemical combination of a specific ratio of atoms of different elements
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In the cathode ray experiment, what observations led to the discovery of electrons?
Cathode rays bent in magnetic field and towards the positive plate in ef
What is the main conclusion in the cathode ray experiment?
cathode rays consist of negatively charged particles found in all matter.
What does J.J. Thomson discover about the electron?
The mass/charge ratio
Who discovers the charge of electron? mass?
Robert Millikan
What is the name of the experiment performed by Robert Millikan?
Oil drop experiment
What does Ernest Rutherford discover?
Ernest Rutherford proposed that atoms consist of a tiny, massive, positive nucleus
surrounded by electrons. He proposed that positive particles lay within the nucleus and called them protons.
- (1891–1974) discovered the neutron, an uncharged dense particle that also resides in
the nucleus.
James Chadwick
The atomic mass unit or * is a unit of relative
mass, but it has an absolute
mass of 1.660543* 10^-24 g.
Dalton
Thus, the atomic mass unit (amu) is * the mass of a carbon-12 atom.
1/12
The mass of an atom is measured * to the mass of an *. The modern standard is the *, whose mass is defined as exactly 12 atomic
mass units.
relative, atomic standard
carbon-12 atom
