P1.1- particle model Flashcards
What was John Dalton’s model named as?
”Billiard Ball ( a “very small indestructible sphere” )
What was J.J. Thompson’s model named as?
“Plum- Pudding Model”
why did the particle model keep changing?
since new evidence can not be explained using old ideas
What is the Rutherford model? (3)
+ positive nucleus (protons + neutrons)
+ negative electrons around
+ almost all mass of an atom is in the nucleus
What is the Bohr model? (3)
+ electrons can only move in fixed orbits in shells around the nucleus
+ the model we use now
+ introduced shells
How big is an atom’s diameter?
+ the diameter of an atom in 10^-10
10 to the power of minus ten
Describe the structure of an atom
draw it out
+ a nucleus containing protons and neutrons
+ electrons moving around the nucleus
Name Five features of Thompson’s model
+ positive mass
+ negative electrons embedded
+ was investigating rays given off by metals (cathode rays)
+ found out that an atom contained negative electrons
+ overall atoms are neutral (no charge)
+ MASS IS OVERALL DISTRIBUTED
What was the main feature of Dalton’s model
all atoms in an element were the same
What is a particle’s nucleus made of?
Protons and Neutrons
How do electrons move around?
In fixed orbits
What experiment did Rutherford do?
Fired alpha particles at a piece of gold foil
(alpha particles are positively charged)
- no need to mention they are positive
What is the length of a molecule?
how and why has the model of the atom changed over time?
- first model of the atom was a hard sphere.
- J. J. Thompson discovered that atoms contain smaller negatively charged electrons.
- model changed to a positive mass with electrons embedded in it
- Then Rutherford discovered that most of the mass was concentrated in a central nucleus.
- new model was a positively charged nucleus with electrons in orbit. - Bohr discovered that electrons could not be in any orbit.
- model changed to a positively charged nucleus with electrons in shells
What is the name of Rutherford’s model?