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concise verbal or mathematical statement of a relationship b/w phenomena that is always the same under the same condition. Ex. Newtowns second law of motion, force = mass times acceleration.
is a unifying principle that explains a body of facts and/or those laws that are based on them. Hypotheses that survive many experimental tests of their validity may evolve into theories. Are always constantly tested. Ex. Big bang theory.
a systemic approach to research. Problem/question, Observation/research, Formulate a hypothesis, Experiment, Collect & Analyze results, Conclusion, Communicate the results
Solid: has both definite shape & a definite volume. The particles that make up a solid are very close together and many times are restricted to a very regular framework called a crystal lattice. Liquid: has a definite volume but no definite shape. It conforms to the shape of its container. The particles are moving much more that in the solid. They are usually clumps of particles moving relatively freely among other clumps. Gas: has neither a definite shape nor volume. It expands to fill its container. The particles are far apart, moving rapidly with respect to each other, and act independently of each other.
measurable value depends on how much matter is being considered. Examples: Mass, which is the quantity of matter in a given sample of a substance, is an extensive property. Volume, defined as length cubed, is another extensive property. Length, The value of an extensive quantity depends on the amount of matter.
measurable value does not depend on how much matter is being considered. Examples: Density, defined as the mass of an object divided by its volume, is an intensive property. Temperature, Color, Unlike mass, length, and volume, temperature and other intensive properties are not additive.
Dalton 4 hypothesis he proposed to describe the nature of matter
Elements are composed of extremely small particles called atoms; All atoms of a given element are identical, having the same size, mass, & chemical properties. The atoms of one element are different from the other elements; Compounds are composed of atoms of more than one element. In any compound the ratio of the #s of atoms of any two of the elements present is either an integer or a simple fraction; A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction.
What was the significance of Rutherford's experiments
He discovered the nucleus (not the neutron); By the gold foil method, measuring the scattering of alpha particles. Most of the particles passed through the gold foil w/little or no deflection. A few were deflected at wide angles. And occasionally, bounced back.; Quoted: "it was as incredible as if you had fired a 15-in shell at a piece of tissue paper and it came back and hit you"
How did this change the model of the atom proposed by Thompson
Rutherford reasoned that if Thomson's model was correct then the mass of the atom was spread out throughout the atom. Then, if he shot high velocity alpha particles (helium nuclei) at an atom then there would be very little to deflect the alpha particles. He decided to test this with a thin film of gold atoms. As expected, most alpha particles went right through the gold foil but to his amazement a few alpha particles rebounded almost directly backwards; These deflections were not consistent with Thomson's model. Rutherford was forced to discard the Plum Pudding model and reasoned that the only way the alpha particles could be deflected backwards was if most of the mass in an atom was concentrated in a nucleus. He thus developed the planetary model of the atom which put all the protons in the nucleus and the electrons orbited around the nucleus like planets around the sun.
The nucleus is the dense central core of the atom. What subatomic particles are contained within the nucleus?
Proton + neutron
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