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Introduction to Atom

Science Study Guide 11/23

Who was Niels Bohr? Niels Bohr was a Danish scientist.
What is the Theory of the 4 Essences? It is the belief that all forms of matter were a combination of earth, air, fire, and water.
Who invented the Theory of the 4 Essences? Aristotle, a Greek philosopher
Who was the Greek philosopher that opposed the Theory of the 4 Essences? Democritus
What did Democritus do? Democritus came up with the idea of the "atom"
Who were alchemists? Alchemists were scientists of the Middle Ages
What were the alchemists' three goals? To turn cheap metals into gold, to stop aging, and to cure diseases
What is a compound? A combination of two or more elements that forms a new substance
What are some examples of compounds? water, salt, sugar, rust, tarnish, and ammonia
Who was John Dalton? an English school teacher who proved Democritus was correct. His nickname is the "Father of the Modern Day Atomic Theory"
What did Dalton do? he proposed his own Atomic Theory
Who was Marie Curie? she was a scientist born in Poland. She worked most of her life with her husband Pierre.
What did Marie Curie study? She and her husband studied radioactive elements. They discovered radium and polonium.
Who was Ernest Rutherford? he was a British physicist.
What did Rutherford do? he discovered that atoms have a nucleus in 1911, and that atoms are mainly empty space. In 1918, he discovered the proton.
What did Niels Bohr originally believe? He originally believed that electrons flew around the nucleus in orbits.
What did Niels Bohr change his beliefs to? he stated that electrons were found on shells (or orbitals) outside of the nucleus. He believed that electrons could "jump" from one shell to another.
What is an element's atomic number? the number of protons in the nucleus of the atom
What is the atomic mass of an element? The number of protons and neutrons in the nucleus of an atom. You could also say it's the total number of nucleons in an atom.
Who do you determine the number of neutrons in an atom's nucleus? you subtract the atomic number from the atomic mass
How many currently known elements are there? 118
How many known elements can be found in nature? 94
What is the electron's relationship to the protons? There are usually the same amount of electrons and protons in an element.
What kind of charge do protons have? positive
What kind of charge do electrons have? negative
What do the charges of the protons and electrons cause? the overall charge of an atom is normally neutral
If fermium has an atomic number of 100 and an atomic mass of 257, how many neutrons are in the nucleus? 157 neutrons
What kind of charge do neutrons have? neutral
Created by: 16arosenberg



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