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Nativity- Atoms

Chapter 11 - Introduction to Atoms

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
Created by: stmvocab