C1 The Atom Flashcards
what is an atom?
smallest part of an element that can exist
what is Daltons model of the atom?
atoms as solid spheres that cannot be divided further
limitations of Daltons Model of atoms
does not account for subatomic particles
presents the atom to be a solid
what is the Plum Pudding model of the atom?
sphere of positive charge with negative electrons embedded in it
who created the Plum Pudding model of the atom?
J.J Thompson
limitations of the Plum Pudding model
no neutrons
no nucleus
what did scientists discover in the alpha scattering experiment?
mass of an atom is concentrated in its centre
(nucleus)
positive charge was also concentrated in the centre (nucleus)
what does the Nuclear model of atom look like?
dense nucleus with electrons orbiting
what did Niels Bohr discover?
that electrons were at a fixed distances
(shells)
where are protons and neutrons in the atom?
nucleus
what is the relative mass of each subatomic particle
proton & neutron - 1
electron - 0
Who discovered the neutron?
James Chadwick
Who discovered the proton?
Ernest Rutherford
How do you calculate number of neutrons in an atom
mass number - atomic number
What is an isotope?
atom (of the same element) with the same number of protons but a different number of neutrons
