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Nativity- Atoms
Chapter 11 - Introduction to Atoms
Question | Answer |
---|---|
atom | the smallest particles of an element that retain the properties of the element |
theory | is a unifying explanation for a broad range of hypotheses and observations that have been supported by testing |
electrons | negatively charged particles |
model | a representation of an object or system |
nucleus | positively charged region in the center of the atom; extremely dense |
electron clouds | regions inside the atom where electrons are likely to be found |
protons | positively charged particles of the nucleus |
atomic mass unit | SI unit used to express the masses of particles in atoms; each proton is weighs one of these |
neutrons | the particles of the nucleus that have no charge and are identical |
atomic number | number of protons in the nucleus |
isotopes | atoms that have the same number of protons but have different number of neutrons |
mass number | the sum of the protons and neutrons in an atom |
atomic mass | the weighted average of the masses of all the naturally accurring isotopes of an element |
four forces at work in an atom | gravity, electromagnetic force, strong force, weak force |
Democritus | said atoms are small indivisible particles of a single material and always moving |
Aristotle | said everything made of water, air, earth, and fire |
John Dalton | expanded on Democritus' theory; everything made of atoms (cant be created, destroyed, or divided) |
JJ Thomson | small particles inside the atom with negative and positive particles; used cathode-ray tube |
Ernest Rutherford | student of thompson-1911 found out- nucleus and electrons flying around |
Niels Bohr | danish scientist- 1913 electron paths and electrons jump levels |