Greek Philosopher's Model Of Matter Flashcards
(25 cards)
What is Democritus model of matter/ what did he do?
He named the atom. He said that the atom is discontinuous. It is empty. It is like a grain of sand.
What was Aristotle model?
He believed that the atom was infinitely divisble
What were John daltons points?
All matter is composed of atoms
All atoms of the same element are identical
Different elements are composed of different size atoms wth their own properties such as mass
Atoms of different elements combine to make up the molecule of a compound
Explain JJ Thomson’s experiment.
He took a cathode ray tube. He connected a power supply to the tube. It was connected to the positive terminal (anode) and negative terminal (cathode). The ray was going in a straight line. The rays caused a small propellor to spin= made up of particles. When a positive and negative plate are placed outside tube, the ray bent towards the positive plate.
What did JJ Thomson discover from his experiment?
The ray is made Up of negative particles because opposites attract since it bent towards the positive plate.
What is a property of a cathode ray?
The rays were identical no matter what metal Thomson used to make the cathode
Who discovered the electron?
JJ Thomson
What did Thomson say?
An atom is divisible (since there are electrons in it)
How did Thomson describe the atom?
It’s a positively charged ball with small negatively charged particles called electrons scattered around
What are alpha particles?
They are positively charged, they are large and heavy, can be stopped by a piece of paper
What are beta particles?
Negatively charged particles
Lighter than alpha particles
Can be stopped by a cheat of foil
What are gamma rays?
They are neutral, not made up of particles but made up of energy
Greatest penetrating power
What was Rutherford’s experiment?
Rutherford bombarded a sheet of gold foil with alpha particles. He surrounded the gold with a detecting screen that lit up every time it was hit with an alpha particle
What were Rutherford’s obversatons?
Most of the alpha particles went right through
Some alpha particles are slightly deflected
Very few bounded right back
What were his interpretations?
The atom is mostly empty space (since some went right through)
The atom contains a very small and dense nucleus
The nucleus is positively charged (protons) = since some bounced right off and some were deflected off
What is Rutherford’s model of the atom?
The atom contains a very small dense positively charged nucleus that has protons. There is then a lot of empty space with the electrons orbiting the edge of the atom
What are properties of protons?
Positively charged
In the nucleus
Are heavier than electrons
What are the Properties of electrons?
Negatively charged
Located at the periphery (around the edge)
are lighter than the protons
What did Bohr discover?
Electrons are not randomly placed at the edge of an atom but are in specific areas called energy levels
Size of the orbit will limit the Capacity of electrons in that shell
What happens when an electron receives energy and get excited?
It jumps to a higher energy level further from the nucleus. The electron quickly returns and it releases new energy in the form of light
What is Rutherford Bohr atomic model?
It is a representation of the atom as a very small nucleus made up of positively charged protons surrounded by negatively charged electrons moving in energy levels
What did James Chadwick discover?
The neutron
What is the role of the neutron and how was it discovered?
The nucleus is made up of charged particles so people started to question as to why the nucleus didn’t explode. The role of the neutron is to hold the protons together in the nucleus
What are the properties of the neutron?
Neutral charged
In the nucleus
Similar mass to protons
