Atomic Structure (Chapter 3)

Question 1

What experiment is Ernest Rutherford associated with?

Answer 1

Gold Foil Experiment

Question 2

What experiment is JJ Thomson associated with?

Answer 2

Cathode Ray Tube (CRT) Experiment

Question 3

What model did JJ Thomson come up with?

Answer 3

Plum Pudding Model

Question 4

What is the plum pudding model?

Answer 4

The plum pudding model says that there was a lot of positive empty space in an atom aside from a few negative electrons (modeled after plum pudding but can also be modeled after a chocolate chip cookie)

Question 5

What did JJ Thomson’s experiment do?

Answer 5

His experiment used a cathode ray tube that vacuumed all of the air out until only the gases that Thomson wanted in it were in it. Then, he ran an electric charge through it which created a beam that ran from the negative to the positive end

Question 6

What did JJ Thomson’s experiment prove?

Answer 6

It proved the existence of the electron

Question 7

What did Ernest Rutherford’s experiment do?

Answer 7

He shot high-energy positive alpha particles at an incredibly small piece of gold foil that was surrounded by a fluorescent screen. He thought that the particles would go right through the foil and show up on the screen behind it, but some of the particles got shot back toward where they came from and appeared on the screen in all sorts of different directions.

Question 8

What did Ernest Rutherford’s experiment prove?

Answer 8

It proved the existence of the nucleus and disproved the plum pudding model. Because most of the particles went through, the atoms must be mostly empty. However, the positive pieces had to be heavy with a small volume (therefore big density) because the particles got turned around so much.

Question 9

What does the Nuclear/Planetary Model say?

Answer 9

It says that electrons are evenly distributed around the small, dense nucleus in the center of the atom and that electrons occupy most of the volume
(Discovered evidence of protons)

Question 10

What does the Bohr model say?

Answer 10

Electrons are in specific energy levels and can jump up an energy level in an “excited” state, but they must come back down and give off light as they lose energy

Question 11

What does the Quantum Mechanical/Electron Cloud Model say?

Answer 11

It determines the energies an electron is allowed to have and says that electrons have the properties of both particles + waves

Question 12

What’s an electron cloud?

Answer 12

The region where you might find an electron

Question 13

What’s the Pauli exclusion principle?

Answer 13

Principle that states that 2 particles of a certain class cannot be in the exact same energy state (basically a pair of electrons cannot have the same spin)

Question 14

Who gets credit for discovering the neutron?

Answer 14

James Chadwick

Question 15

What is Aufbau’s principle?

Answer 15

Principle that states that the structure of each element is obtained by adding one proton and electron each to an atom (electrons must go to lowest-energy orbital available)

Question 16

What is Hund’s rule?

Answer 16

Rule that states that for an atom in the ground state, the # of unpaired electrons is the maximum possible and these unpaired electrons have the same spin

Question 17

What was Dalton’s 1st atomic theory?

Answer 17

1. All matter is made of atoms and it is impossible to destroy, create, and/or divide an atom
2. Atoms of the same element are alike in their physical and chemical properties.
3. Atoms of different elements are different in their physical and chemical properties.
4. Atoms of different elements combine in whole number ratios to form compounds.
5. In a chemical reaction atoms combine, separate or rearrange. No new atoms are created or destroyed.

Question 18

Which 2 parts of Dalton’s atomic theory were disproved and why?

Answer 18

1. All matter is made of atoms and it is impossible to destroy, create, and/or divide an atom - We can now divide an atom, it’s done in nuclear plants
2. Atoms of the same element are alike in their physical and chemical properties - Isotopes exist and are not identical to other atoms of the element

Question 19

What are isotopes?

Answer 19

Isotopes are atoms of an element that have the same number of protons but a different number of neutrons (same atomic #, different mass #)