Atomic Structure Flashcards
what is an atom
smallest part of an element that can still be recognised as part of that element
what is dalton’s model of the atom
a solid sphere that can’t be divided into smaller parts
what is the plum pudding model of the atom
sphere of positive charge with negative electrons embedded in it
what did scientists discover in the alpha scattering experiment
some alpha particles were deflected by the gold foil this showed an atoms mass and positive charge must be concentrated in one small space - the nucleus
describe nuclear model of the atom
dense nucleus with electrons orbiting it
what did Niels Bohr discover
electrons orbit in fixed energy levels (shells)
what did James Chadwick discover
uncharged particle called the neutron
where are protons and neutrons
in the nucleus
what is the relative mass of each sub-atomic particle
proton = 1
neutron = 1
electron = 0 (very small)
what is the relative charge of each sub-atomic particle
proton = +1
neutron = 0
electron = -1
how can you find out the number of protons in an atom
atomic number on periodic table
how can you calculate no of neutrons in an atom
mass number - atomic number = neutrons
why do atoms have no overall charge
equal numbers of positive protons and negative electrons
how many electrons go in 1st, 2nd and 3rd shell
up to 2 in first shell
up to 8 in each of the second and third shells
what is an element
substance made of one type of atom
