4.1 Development of the Atomic Theory

Question 1

the smallest unit of an element that maintains the properties of that element

Answer 1

atom

Question 2

a subatomic particle that has a negative charge

Answer 2

electron

Question 3

in physical science, an atom’s central region, which is made up of protons and neutrons

Answer 3

nucleus

Question 4

a region around the nucleus of an atom where electrons are likely to be found

Answer 4

electron cloud

Question 5

philosopher
Experiment: just observations
Discovered: thought that matter is composed of atoms

Answer 5

Democritus

Question 6

Experiment: experimented with different substances
Discovered: based his theory on observations of elements combine
all substances are made of atoms; atoms are small particles that cannot be created, divided, or destroyed
atoms of the same element are exactly like, and atoms of different elements are different
atoms join with other atoms to make new substances

Answer 6

Dalton

Question 7

Experiment: used a cathode-ray tube like structure, invisible beam was produced, metal plates (charged) could change path of beam
Discovered: electrons in atoms, when the plates were charged, the invisible beam was moved down, when not charged, the invisible beam went straight, made a plum pudding model (his model was incorrect because it just showed the outer area of the model, not the inside too, said it went throughout the whole pudding(particle)

Answer 7

Thomson

Question 8

Experiment: aimed a beam of small, positively charged particles at a thin sheet of gold paper
Discovered: that atoms are mostly empty space with a dense, positive nucleus

Answer 8

Rutherford

Question 9

Experiment: studied the way atoms react to light
Discovered: proposed that electrons are located in levels at certain distances from the nucleus

Answer 9

Bohr

Question 10

Experiment: made a model to show that electrons stay inside electron clouds
Discovered: the electron-cloud model represents the current atomic theory

Answer 10

20th-century scientists; specifically Erwin Schrodinger and Werner Heisenberg

Question 11

philosopher
Experiment: also observations
Discovered: knew there was something that made up everything, he was wrong (thought that you could never end up with a particle that couldn’t be cut)

Answer 11

Aristotle