1.1- FUNDAMENTAL PARTICLES Flashcards
What did Robert Boyle propose in 1661?
that there were some substances that could not be made simpler- chemical elements as we know now
What did John Dalton suggest in 1803?
elements were composed of indivisible atoms
all the atoms of a particular element had the same mass and atoms of different elements had different masses
atoms could not be broken down
What did Henri Becquerel discover in 1896?
radioactivity
What did the discovery of radioactivity show?
particles could come from inside the atom. therefore the atom was not indivisible
What did J J Thompson discover in 1897?
electrons- this was the first sub-atomic particle to be discovered
What did Thompson show?
electrons were negatively charged and electrons from all elements were the same
Where did Thompson suggest the electrons were located?
within the atom in circular arrays, like plums in a pudding of positive charge
What did Ernest Rutherford and his team find out in 1911?
most of the mass and all the positive charge of the atom was in a tiny central nucleus
What three fundamental particles are atoms made of?
protons, neutrons and electrons
What do the protons and neutrons form?
the nucleus, in the center of the atom
What are protons and neutrons sometimes called?
nucleons as they are found in the nucleus
How is the electrons positioned?
they surround the nucleus
What is the relative mass of an electron?
1/1840
How are the protons and neutrons held together at the center of the atom?
by a force called the strong nuclear force
How strong is the strong nuclear force in comparison to the electrostatic forces?
much stronger
