P1.1.1/P1.1.2 - The model of the atom Flashcards
What was Dalton’s model?
It was a very small indestructible sphere
What did Dalton think about atoms?
All atoms in an element are the same
The atoms in one element are different from the atoms that are in other elements.
E.g. Gold atoms are not the same as Iron atoms
What J.J Thomson’s model?
It was a plum pudding model which represents negative electrons embedded in positive mass
What did Thomson discover?
He discovered that cathode rays are from particles with less than 1/1000 of the mass of a hydrogen atoms. He found a particle inside an atom called the electron.
What did Thomson realise?
An atom contains negative electrons
Overall, atoms have no electrical charge
What experiment did Rutherford do?
He did an experiment with Ernest Marsden and Hans Geiger in which he they shot alpha particles (positive) at a piece of gold foil. Most went through but a few bounced back
From Ernest Rutherford’s experiment what did he conclude?
He suggested that atoms are made from tiny positive nucleus with electrons around the outside. Almost all the mass of an atoms is in its nucleus. Later, scientists discovered the nucleus is made 2 different types of particles called protons and neutrons
What is the Bohr model?
Bohr’s model is an improved version of Rutherford’s model. He suggested that electrons can only move in fixed orbits called electron shells
