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chemistry chapter three

Terms in this set (37)

law of definite proportions
(chemistry) law stating that every pure substance always contains the same elements combined in the same proportions by weight or mass
law of conservation of mass
Matter is not created nor destroyed in any chemical or physical change
law of multiple proportions
the law that states that when two elements combine to form two or more compounds, the mass of one element that combines with a given mass of the other is in the ratio of small whole numbers
what is the atomic theory?
the theory that states that atoms are the building blocks of all matter
according to Dalton, what is the difference between an element and a compound?
elements are composed of only one kind of atom and compounds are made from two or more kinds of atoms
Dalton's five principles of the atomic theory
1. all matter is composed of extremely small particles called atoms, which cannot be subdivided, created, or destroyed
2. Atoms of a given element are identical in their chemical and physical properties
3. Atoms of different elements differ in their physical and chemical properties
4. atoms of different elements combine in simple, whole number ratios to form compounds
5. in chemical reactions, atoms are combined, separated, or rearranged but never created, destroyed, or changed
which one of Dalton's principles still apply to the structure of an atom
the last three
electron
A subatomic particle that has a negative electric charge
nucleus
atom's central region, which is made up of protons and neutrons
proton
A subatomic particle that has a positive charge and that is found in the nucleus of an atom
neutron
A subatomic particle that has no charge and that is found in the nucleus of an atom
atomic number
Number of protons in the nucleus of an atom
mass number
Sum of the number of protons and neutrons in the nucleus of an atom
isotope
An atom with the same number of protons and a different number of neutrons from other atoms of the same element.
what subatomic particle was discovered with the use of a cathode ray tube
electrons
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