Matter & The atom Flashcards
What ttype of particles can matter be made from
Atoms, molecules and ions
What is diffussion
-The evidence for the existence of small particles
the movement of particles from areas of high concentration to areas of low concentration
Law of conservation of mass / matter
The mass of a closed system will remain constant, regardless of the processess acting inside the system.
matter cannot be created or destroyed although it can be rearranged
for any chemical reactions, mass of reactants must equal mass of prducts
What did the greeks discover
First to propose that matter was composed of minute particles
democritus - atomos meaning uncuttable, atom
Daltons atomic theory
-all matter is made up of very small particles called atoms
-all atoms are indivisible
-atoms cannote be created or destroyed’
What did crookes tube demonstrate
Rays coming from the cathode cast a shadow.
connected to the negative electrode
cathode
connected to the positive electrode
annode
explain vaccuum tubes
-Gas at low press.
-electric current passed through
-radiation came from the end of the tube connected to the cathode
-cathode rays
What did dalton discover
- Rays cast shadows, travelled in straight lines
- causes glass to glow (flouresce)
- turns a paddle wheel
- Rays are made of particles
What did george stoney do
Named the negative particle electron
What did jj thomson do
Discovered the elctron
Briefly explain thomsons experiment
Beam of cathode rays througha small hole in the anode
beam passed between two metal plates.
beam could be deflected by electronic plates.
therefore beam is made of negative particles
What did thomson use to delflect the elecron
magnetic field from an electromagnet
What did thomson calculate
The ratio of charge to mass for the electron
Cathode rays
Streams of negatively charged particles called electrons.
They travel in straight lines from the cathode to anode.
Are deflected by electric and magnetic fields
Have sufficient energy to move a small object such as a paddle wheel
Thomsons plum pudding model
A sphere of positive charge with negative elesctrons embedded in it at random
What was robert milikans experiment called
The oil drop exxperiment
What did the oil drop experiment do
Measured the charge on the electron
Explain the oil drop experiemny
- X rays ionised air molecules by stripping electrons of their atom.
- Oil droplets picked up these electrons and became negative
- He increased the positive charge until the droplet hovered.
- Took measurement and calculated the charge on the electron.
What did ernest rutherford do
Fired alpha particles at a thin gold foil
-Thomsons plum pudding model predicted they would pass through with little defelction
What the result of the gold foil experiment
Most passed through undeflected, however some bounced right back
Explanation for gold foil experimnt
- Hard dense core of positive matter in the center of each atom. the nucleus
- Atoms are mostly empty space
Observations of the gold foil experiment
- Most alpha particles passed straight through undeflected
ATOMS ARE MOSTLY EMPTY SPACE - Some alpha particles are deflected at large angles
THE ALPHA PARTICLES ARE REPELLED WHEN THEY ARE NEAR THE NUCLEUS - A small number of alpha particles are reflected back along their own paths
HIT HEAD ON WITH NUCLES OF THE ATOM
Who discovered the proton how
Rutherford
continued to bomabrd different element such as nitrogen and oxygen.
Small particles were given off- protons
Who discovered the neutron how
James chadwick bombarded beryllium with alpha particles.
small particles were gien off that were neutral and had the same mass as the proton - the neutron.
