The Atom CH2 Flashcards
Particulate nature of matter
Idea that materials are made of small particles.
Who and when first put forwards the atomic theory?
John Dalton 1808
what did Join Dalton summaries
All matter is made up of very small particles called atoms and atoms are indivisible.
Who Discovered cathode ray?
William Crookes
How was cathode ray discovered (1st experiment)
Passing electric currents through a glass tube containing air.
What happened when cathode rays are strike glass?
It causes it to glow or fluoresce.
What did Crooks conclude in this experiment of cathode rays?
Cathode rays travel in straight line, causes glass to fluoresce when glass strikes it and posses enough energy to move the paddle wheel.
Cathode Rays
Streams of negatively charged particles called electrons. They travel in straight lines from the anode.
Who was credited with the discovery of an electron
Robert Millikan
Why was the cathode rays attracted to the plates when they were charged?
the negative charged electrons being attracted to the positive plates.
Who was credited for discovering the charge on electrons?
Robert Millikan
What was the oil drop test?
Placing negatively charged oil droplets between two charged plates
Who proposed the plum pudding model?
J.J Tompson
How was the plum model described?
An atom is like a sphere of positive charge and electrons are embedded in them at random.
Who preformed a experiment which led to the discovery of the nucleus?
Enest Rutherford
What did Ernest Rutherford do to gold foil?
Bombarded a piece of gold foil with alpha particles
What did the experiment that discovered the nuclease conclude?
Most alpha particles passed straight through the foil, some were deflected at large angles as they came close to the positive charge of the nucleus and some alpha particles reflected back along their original path.
Who discovered the proton?
Rutherford.
How was the proton found?
He found when he bombarded lighter substance such as oxygen and nitrogen, Small positively charged particles were given off.
Who proposed the new structure of the atom?
Rutherford
Who discovered the neutron?
James Chadwick
How was the neutron discovered?
Alpha particles were knocking neutral particles out of the beryllium and neutral particles were knocking protons out of the wax block.
