P7 - (Part 1) Atomic Structure Flashcards
Radius of an atom
1 x 10 ^-10 m
Radius of nucleus relative to atom
The radius of the nucleus is 1/10000 the size of the whole atom
Difference in energy between energy levels
Energy levels which are further from the nucleus are at a higher energy level than those closer to the nucleus
How does an electron move up or down and energy level
- It can move to a higher energy level by absorbing radiation
- It can move back down by emitting radiaiton
Early ideas about atoms
- Greeks believed everything was made of atoms
- They thought atoms where tiny spheres that couldn’t be divided
What was discovered in 1897
Small, negative particles in the atom called electrons
What was the plum pudding model
- A ball of positive charge with negative elctrons randomely embedded in it
How was the alpha scattering experiment conducted and what did they see
- Fired alpha particles (positive particles) at gold foil
- Most particles passed straight through
- Sometimes the alpha particles were deflected
- Some alpha particles bounced straight back
Conclusions made from the alpha scattering experiment
- Most went straight through - atoms are mainly empty space
- Some were deflected - centre of atom must have a positive charge
- Some bounced back - mass of atom was concentrated in the centre (nucleus)
Lead to development of the nucelar model of the atom
What did Niels Bohr propose and why was it accepted
- Electrons orbit the nucleus at specific distances
- His calculations agreed with the results of other scientists’ experiments
these are now called energy levels
What did scientists discovered in 1919
The positive charge was caused by positive particles called protons
When and what did James Chadwick discover
1932 - proved the existence of a neutral particle called neutrons and therefore proved the existence of the nucleus
What are isotopes
Atoms of the same element with varying numbers of neutrons
