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chem popquiz (22-24)
Question | Answer |
---|---|
Democritus | Greek scholar that proposed that matter consists of tiny particles; thought particles of water were smooth and round, particles of iron were rough and jagged |
atomos | "indivisible" "uncut"what Democritus called the particles that make up matter |
John Dalton | proposed a more extensive model of the atom |
differences in the atoms of the elements. 4) The atoms of the elements combined in a compound are combined in a definite ratio. 5) A chemical reaction is the result of rearrangement, combination, or separation of atoms. | ATOMIC THEORY 1) Every element consists of tiny, indivisible, indestructible particles called atom. 2) All of the atoms of a particular element have the same size, mass, and chemical behavior. 3) Differences in properties of elements result from |
chemical reaction | result of rearrangement, combination, or separation of atoms |
no | is Dalton's atomic theory completely accurate? |
law of definite composition | first basic law explained by Dalton's theory; ratios of the masses of each element in a given compound are always the same |
a compound always has the same composition and the same properties no matter what | law of definite composition restated |
law of multiple proportions | when two elements can combine to form more than one compound, the masses of one element that combine with a fixed amount of the other element are in a ratio of small whole numbers |
properties | how to describe, identify, or distinguish a matter |
physical properties | can be measured without changing the identity/composition of the substance |
color, odor, density, hardness, solubility, taste, state, boiling point, melting point | examples of physical properties |
chemical properties | describe how matter reacts to change into other chemically different substances having different properties |
chemical properties | can only be determined through chemical reactions, which change the identity of the substance |
physical changes | changes in the physical appearance of matter that do not change the identity or chemical composition of a substance |
state, shape, phase | examples of physical changes |
physical processes | physical changes may often be reversed by what |
chemical change | a change in which a substance becomes a different substance with a different composition and properties |
sodium chloride | major example of chemical change |
other chemical changes | chemical changes can be reversed only by |
formation of a gas or precipitate liberation/absorption of heat, light, etc (energy) a distinct change in color | number of observations that suggest a chemical change has occurred |
Precipitate | An insoluble substance |