Modern Atomic Theory

Dalton’s Atomic Theory

1. All matter is made of tiny indivisible particles called atoms.
2. Atoms of the same element are identical, those of different elements are different.
3. Atoms of different elements combine in whole number ratios to form compounds.
4. Chemical reactions involve the rearrangement of atoms. No new atoms are created or destroyed.

J.J. Thompson

<aside> 💡 Claim: Electrons Evidence: They shoot a charge through a cathode tube and there is a positive and negative end. The charge bends towards a positive and away from the negative. This tells us that it is negative. Reason: He reasoned that the positives surrounded the negatives

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Plum Pudding Model:

• Spherically shaped
• Electrons positioned throughout it like chocolate chips in a cookie.
• The sphere was a positively charged mass, like the cookie dough
• Idea didn’t last long

Rutherford

Protons

Ernest Rutherford shoots a beam of radiation particles at a thing sheet of gold foil

• Some particles went through, some bounced back, some went through at an angle.
• The atom was made up of mostly empty space where the electrons moved.
• The positive charge of the atom was within the center of the atom: The nucleus - a small dense positively charged space at the center of the atom