Electrostatic Charges
Tommy the turtle is overall positively charged. He slowly crawls over to Bob to give him a hug and Bob gets repelled away. What do you think Bob's overall charge is?
Bob is positively charged.
John Dalton modeled the atom as a solid, indivisible ______.
Sphere
Rutherford discovered that the atom is mostly empty space with a small, dense, positive ______.
Nucleus
What is the main difference between Bohr's model of electron paths and Schrodinger/Heisenberg's quantum model?
Bohr placed electrons in fixed circular orbits, while together Schrodinger and Heisenberg proved electrons exist in 3D regions of probability (electron clouds/orbitals).
What piece of lab equipment did J.J. Thomson use to show that a beam of light was actually made of negative particles?
Cathode Ray Tube
You rub two birthday balloons on your hair, giving them both a positive charge. When you try to push the two balloons together to tie them, they refuse to touch and push away from each other. Why?
Because they both have the same (positive) charge! Like charges always repel.
J.J. Thomson used a cathode ray tube to discover which negatively charged subatomic particle?
Electron
What type of charged particles did Rutherford shoot at the gold foil?
Positively charged alpha particles
True or False: Modern quantum theory states that electrons travel in exact circular tracks like planets around the sun.
False – They exist in 3D electron clouds/probability regions
In Rutherford's Gold Foil Experiment, what happened to most of the alpha particles shot at the gold foil?
They passed straight through without stopping or bending
Jeremy the teddy bear has no charge (neutral). When Tommy the turtle (positively charged) crawls over, Jeremy slowly leans toward Tommy instead of pushing away. Why?
Jeremy is neutral! Neutral objects are pulled toward charged objects—they do not push away (repel)
Did John Dalton believe that atoms contained positive and negative charges?
No, he thought atoms were solid spheres with no smaller parts or charges
Bohr modified Rutherford's model by placing electrons in fixed, circular energy paths called ______.
Orbits
The Heisenberg Uncertainty Principle states that you cannot simultaneously know an electron's position and ______.
Velocity / Speed / Momentum
What electrical property causes two positive charges to push away from each other without touching?
Repel/Repulsion
Jimmy slides down a plastic playground slide and his hair stands straight up on end—every single strand of hair is pushing away from the strands next to it! What does this tell you about the charge on each strand of Jimmy's hair?
All the strands have the same charge! Because every strand acquired the exact same type of charge from the slide, they all repel each other, forcing his hair to fan out in every direction.
What was the name of J.J. Thomson’s model that showed electrons scattered throughout a positive sphere?
Plum Pudding Model
Why did Rutherford need to use positively charged alpha particles instead of neutral particles to detect the nucleus?
Because like charges repel, allowing electrostatic repulsion to deflect particles away from the positive nucleus
What do we call the 3D regions of high probability where electrons are located in the modern model?
Electron Clouds
What evidence forced scientists to abandon Dalton's idea that an atom could not be divided into smaller pieces?
The discovery of the subatomic particle / electron by Thomson
Penelope the cat is fast asleep on a fuzzy fleece blanket. When she stands up and walks past a hanging metallic curtains tassel, the tassel swings away from her without her even touching it! If Penelope became negatively charged by rubbing on the blanket, what charge did the curtain tassel have?
Negative! Since like charges repel, the negative tassel pushed away from negative Penelope.
Complete the frame: Thomson changed Dalton’s model because new experimental evidence proved the atom was not ______.
Indivisible/Solid
Why were Rutherford's scientists shocked when a few alpha particles bounced straight backward off the gold foil?
Because they expected the atom to be soft like Thomson's plum pudding model, where particles would pass straight through
What is the primary purpose of developing a new scientific model when an old model has been used successfully for decades?
To account for new experimental evidence/data that exposes limitations or data gaps in the old model
What specific experimental result in Rutherford's gold foil experiment proved that an atom's positive charge is concentrated in a tiny, dense center rather than spread out evenly?
Only a small amount of positive charged alpha particles hit a target causing them to deflect or bounce straight backwards