Physics modern 1

What was Thomson’s plum pudding model?

• Electrons floating in a positively charged sphere.

What experiment did Rutherford perform?

• The gold foil experiment.

What did Rutherford discover?

• Atoms are mostly empty space with a small dense positive nucleus.

If an atom were the size of a football field, how big would the nucleus be?

• About the size of a marble.

What is the Bohr model of the atom?

• Electrons orbit the nucleus at specific energy levels.

Can electrons exist between Bohr energy levels?

• No.

What happens during photon emission?

• An electron moves to a lower energy level and releases energy.

What happens during photon absorption?

• An electron moves to a higher energy level and gains energy.

What type of spectrum is produced during emission?

• Bright-line spectrum.

What type of spectrum is produced during absorption?

• Dark-line spectrum.

What equation finds energy released during electron transitions?

Ephoton=Ei−Ef

If Eᵢ − Eƒ gives a negative answer, what do you do?

• Drop the negative sign.

What determines the color of emitted light?

• The energy/frequency of the photon.

What is ionization energy?

• The energy needed to remove an electron from an atom.

What is the ground state?

• The lowest and most stable energy level.

What is the currently accepted atomic model?

• The electron cloud/quantum mechanical model.

Who proposed the electron cloud model?

• Erwin Schrödinger.

What does the electron cloud model say?

• Electrons exist in regions of probability around the nucleus.

What does the electromagnetic force explain?

• Electricity, magnets, lightning, atoms, and chemical reactions.

Can electromagnetic force attract and repel?

• Yes.

What is gravitational force?

• An attractive force between objects with mass.

Which fundamental force is weakest?

• Gravity.

What does the strong nuclear force do?

• Holds protons and neutrons together in the nucleus.

Is the strong force attractive or repulsive?

• Attractive only.

What does the weak force control?

• Radioactive decay of subatomic particles.

What are hadrons?

• Particles made of quarks that experience the strong force.

What are baryons?

• Hadrons made of 3 quarks.

What are mesons?

• Hadrons made of 1 quark and 1 antiquark.

What are quarks?

• Fundamental particles that make up hadrons.

Do quarks have whole-number charges?

• No, they have fractional charges.

What are leptons?

• Elementary particles that are not made of smaller particles.

What is the most familiar lepton?

• The electron.

What are antiparticles?

• Particles with the same mass but opposite charge as normal particles.

What happens when a particle meets its antiparticle?

• They annihilate and become energy.

How is an antiparticle symbol written?

With a bar above the symbol.