4.1 Development of the Atomic Theory

Question 1

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

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

Greek philosopher that was the first person to imagine an atom. He thought ‘atoms’ were small, hard particles made from a single material and formed different shapes and sizes that COULD NOT be cut

Answer 5

Democritus

Question 6

Greek philosopher that believed you would never end up with a particle that couldn’t be cut

Answer 6

Aristotle

Question 7

Chemist that experimented with different substances to figure out why elements combine in certain proportions. His results proved that this is because they are made up of a single atom. He created his atomic theory : 1. all substances are made of atoms, which are small particles that can’t be divided, created, or destroyed. 2. atoms of the same element are exactly alike, and atoms of different elements are different. 3. atoms join with other atoms to make new substances

Answer 7

Dalton

Question 8

Scientist that discovered that there are small particles inside the atom (which means that atoms can be divided into even smaller parts) and proved there was a mistake in Dalton’s theory. He experimented with a cathode-ray tube and found that negatively charged particles are present in every kind of atom, which are now called electrons. He also thought electrons were mixed in an atom like plums in plum pudding

Answer 8

Thomson

Question 9

Scientist that wanted to test Thomson’s theory.H used a gold-foil experiment to see if particles would past straight through the gold foil, like he thought they would, he was proved wrong. From this experiment, he stated that atoms are soft ‘blobs’ of matter. Although most of the particles went straight through the gold foil, some of them were deflected / turned to one side

Answer 9

Rutherford

Question 10

Scientist that studied how atoms react to light. His results led him to propose that electrons move around the nucleus in certain paths / energy levels. He stated that electrons can jump from a path in one level to a path in another level

Answer 10

Bohr

Question 11

Physicist that further explained that nature of electrons in the atom. For example, he stated that electrons DO NOT travel in a certain path. In fact, the path of an electron can’t be predicted. He also discovered that there are regions inside the atom where electrons are likely to be found, called electron clouds

Answer 11

Schrodinger and Heisenberg