History of the Atom Flashcards
What is Daltons Atomic Theory
All matter is made up of very small particles called atoms
All atoms are indivisible , they cannot be broken down into simpler particles
What was Crookes experiment and what did he discover
The Maltese Cross experiment
Cathode rays
What did Crookes conclude from the experiment
Cathode rays travel in straight lines
Cause glass to glow ( fluoresce)
Made of particles
What did Thomson discover and how
Electrons
By showing cathode rays were attracted to the positive plate in an electric field
Name and Explain Thomsons model for an atom
Plum Pudding model
Positively charged sphere with negatively charged electrons embedded in it
Who came up with the name for electrons
Stoney
What was Milikans experiment
Oil drop experiment
charged oil drops using X-rays and measured charge to stop them falling
What did Milikan measure with the oil drop experiment
The Mass of Electron
Explain Rutherfords experiment
Gold Foil Experiment
Fired alpha particles at a thin sheet of gold foil
What were the results of Rutherfords experiment and what did he conclude
Atom mostly empty space - most of the particles passed through and were not deflected
Nucleus has a positive charge - some deflected at small angles
Nucleus is very dense - some deflected at large angle/ bounced straight back
Who discovered protons and how
Rutherford
Continued bombarding substances with alpha particles
Who discovered neutrons and how
Chadwick
By bombarding Be with alpha particles
What did Moseley discover
Atomic Number
What is the Atomic Number
The number of protons in the nucleus of an element
What is the Mass Number of an atom
The sum of the number of protons and neutrons in the nucleus of the atom
