C1 Atomic Structure Flashcards
Who is John Dalton
He thought the atom was a solid sphere that couldn’t be divided ino smaller parts. His model did not include protons,neutrons or electrons
The plum pudding model
Scientists found out about sub-atomic charged particles. The first found were electrons
This led to the model of the atom, a cloud of posative charge, with negative electrons embedded in it.
Alpha scattering experiment
- Scientists fired small, positively charged particles (called alpha particles) at a piece of gold foil only a few atoms thick.
- They expected the alpha particles to travel
straight through the gold. - They were surprised that some of the alpha
particles bounced back and many were deflected
(alpha scattering). - To explain why the alpha particles were repelled
the scientists suggested that the positive charge
and mass of an atom must be concentrated in a
small space at its centre. They called this space
the nucleus.
Nuclear model
Scientists replaced the plum pudding model with the nuclear model and suggested that the electrons oribut the nucleus, but not at set distances
What was Niels Bohr’s model ?
Electron shell (Bohr) model, Niels calculated that electrons must orbit the nucleus at fixed distances. These orbits are called shells or energy levels
The proton discovery
Experiments provided evidence that the nucleus contained smaller particles called protons. A proton has an opposite charge to the electron
What did James Chadwick discover
James Chadwick carried out experiments that gave evidence for a particle with no charge. Scientists called this the neutron and concluded that the protons and neutrons are in the nucleus, and the electrons orbit the nucleus in shells.
Relative mass
The mass of electrons, protons and neutrons comapered to eachother
What is an element ?
Substances made of one type of atom
What are compounds ?
Made of different types of atoms chemically bonded together
What is a mixture ?
Consists of two or more elements or compunds that arn’t chemically combined together. The substances in the mixture can be sperated using physical processes. Thes processes don’t use chemical reactions
How do you sperate mixtures ?
Filtration
Crystallisation
Simple distillation
Fractional distillation
Papaer chromatography
Filtration
Insoluble solids and a liquid
Crystallisation
Soluble solids from a solution
Simple distillation
Solvent from a solution
