scientific models and atomic history

Question 1

what are the three physical states of matter?

Answer 1

Solid, liquid, gas

Question 2

what is matter?

Answer 2

Matter has a mass and occupies space. Matter is identifiable by its properties.

Question 3

what are models?

Answer 3

a model is a mental or physical representation of something else.

Question 4

what are models used for?

Answer 4

Models are used in science to explain different phenomenon like the physical properties of matter.

Question 5

Explain dalton’s atomic model.

Answer 5

1. All matter consists of small particles.
2. all particles of the same substance are identical.
3. the spaces between the particles are very large compared to the particles themselves.
4. particles in matter attract each other.
5. all particles are in CRRM ( constant,rapid,random straight line motion )

Question 6

explain j.j thomson’s atomic model.

Answer 6

• performed experiment with cathode ray tubes and coined the term “electron”
• the electron was negatively charged particle that was part of the atom but that could detach itself from the rest of the atom.
• atom are therefore NOT invisible like dalton said.
• he modified Daltons model to include electrons

Question 7

what did Ernest Rutherford work with? explain.

Answer 7

he worked with radioactive substances to learn about how electrons were distributed within an atom.

Question 8

explain the goldfield experiment

Answer 8

piece of gold foil was hit with alpha particles, which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space. Some particles had their paths bent at large angles.

Question 9

what happened with the gold foil experiment?

Answer 9

• most particles passed all the way through the piece of gold foil.
• some particles were deflected at large angles.
• some particles were deflected at small angles.

Question 10

conclusion drawn from the gold foil experiment.

Answer 10

• atom is mostly empty space
• atom has a hard, dense, very small center = nucleus
• the nucleus must be positively charged.

Question 11

simplified model of the atom

Answer 11

The three parts of the atom are protons (positively charged), neutrons (neutral charge), and electrons (negatively charged). Protons and neutrons form the atomic nucleus.

Question 12

explain the neutron

Answer 12

a neutrally charged particle found in the nucleus of the atom along with the protons, its role is to hold the protons together. ( discovered by james chadwick )

Question 13

Explain aristotle’s model

Answer 13

Proposed that water, air, fire, earth were the elements (gained large acceptance at the time)

Question 14

Explain democritus’s model

Answer 14

Proposed a model more similar to current thought ; atoms are small particles that make up matter.