Unit Two - Atomic Theory Flashcards
What theory did Democritus propose
The atomic theory
What does Democritus’ atomic theory explain
All atoms are small, hard, indivisible, and made of a single material
What did Democritus name the particles he “found”
Atomos
Did Democritus experiment for his discoveries
No
What atomic ideologies did Aristotle hold
Aristotle denounced the atom, saying that everything was made up of fire, earth, air, and water
- hot, cold, wet, dry
Did Aristotle experiment?
No
Did John Dalton conduct his own experiments
No
What did John Dalton propose in 1803
Dalton’s Atomic Theory
What we’re Daltons postulates
- Matter is composed of atoms
- All elements of an element are identical
- Atoms cannot be broken, created, or destroyed
- Atoms of different elements come together to form ratios and compounds
- In chemical reactions, atoms are combined, separated, or rearranged
What did Thomson discover about particles
Particles contained negatively charged particles
What did Thompson use to discover electrons
Cathode tube rays, magnetic and electric fields
What was Tompson’s model
The plum pudding model
What did Rutherford discover with the gold foil experiment
That atoms contained a nucleus
What was the gold foil experiement
A bombardment of alpha particles given off by uranium onto a piece of gold foil
What were the final conclusions from Rutherford’s experiment
- The atom is mostly empty
- Positively charged core where most of the mass was concentrated
What did Bohr discover
Electrons were arranged in fixed circular paths
What did Millikan discover
That electrons were negatively charged
What sub-atomic particle did Chadwick discover
The neutron
What is the weight of an electron
0.0005 amu
What does the atomic number of an element represent
The amount of protons in an atom
How do you find the number of neutrons in an atom
Neutrons = mass number - atomic number
What are isotopes
Atoms of the same element with differing amounts of neutrons
