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The Atom. Law of Conservation of Mass. Was discovered by Antoine Lavoisier Helped moved alchemy to be chemistry Mass cannot be created nor destroyed in normal chemical or physical processes. Aristotle – the four basic elements -Earth -Air -Water -Fire. Democritus Follower of Leucippus
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Law of Conservation of Mass • Was discovered by Antoine Lavoisier • Helped moved alchemy to be chemistry • Mass cannot be created nor destroyed in normal chemical or physical processes.
Aristotle – the four basic elements -Earth -Air -Water -Fire
Democritus • Follower of Leucippus • An Atomist • Coined the word atomos meaning uncuttable or the smallest particle of matter
2000 years later • John Dalton • – School Teacher • Five main points of Dalton's atomic theory • Elements are made of tiny particles called atoms. • All atoms of a given element are identical.
3. The atoms of a given element are different from those of any other element; the atoms of different elements can be distinguished from one another by their respective relative atomic weights. 4. Atoms of one element can combine with atoms of other elements to form chemical compounds; a given compound always has the same relative numbers of types of atoms. 5. Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process; a chemical reaction simply changes the way atoms are grouped together.
Plum Pudding Model of the Atom JJ Thompson
Atomic Number: The number of protons in the nucleus of an atom Mass Number: The total number of protons and neutrons on a nucleus Atomic Number Symbol Atomic Mass
Isotope: Atoms of the same element that have different masses
Determining the number of protons neutrons and electrons in an isotope. # of protons = atomic number 17 # of neutrons = mass number – atomic number 35 - 17= 18 # of electrons = # of protons in a neutral atom 17 35 17 Cl # of protons = atomic number 35 # of neutrons = mass number – atomic number 80 – 35 = 45 # of electrons = # of protons in a neutral atom 35 Bromine-80
Practice!! Aluminum -27 Copper-65 B Xe Lead-208 protons-13 neutrons-14 electrons-13 protons-29 neutrons-36electrons-29 protons-5 neutrons-6electrons-5 protons-54neutrons-77electrons-54 protons-82 neutrons-126electrons-82 11 5 131 54