development of model of atom Flashcards
what was Dalton’s theory?
Dalton thought atoms were hard spheres and the elements only had one type of atom
Who discovered the plum pudding model and what was it?
JJ Thompson discovered the electron (tiny negatively charged particle) and described atoms like ‘plum puddings’ with negative charges embedded in a cloud of positive charge
what experiment did Geiger a Marsden do?
They fired Alpha particles at Gold Foyle which showed atoms could not be solid
What was Rutherford’s theory?
Rutherford proposed that the positive charge of an atom is in a small centre which called the nucleus and electrons orbit the nucleus
what did Rutherford call his model?
The nuclear model
what did Neils Bohr suggest?
Electrons orbit at set distances in energy levels/shells
What did James Chadwick discover?
The neutron which has no charge and has the same mass as the proton
before the discovery of protons, electrons and neutrons, how did scientists order the elements?
By their atomic weight
how did Mendeleev group elements?
He grouped elements with similar properties so patterns could be seen
how are the elements on the modern periodic table arranged?
In order of increasing atomic number
What are the columns on the periodic table called?
Groups
What are the rows on the periodic table called?
Periods
The number of electrons in the atom shell of an atom is the same as what?
Its group on the periodic table
