#P1.1a
describe how and why the atomic model has changed over time
the Thomson, Rutherford (alongside Geiger and Marsden) and Bohr models
#P1.1b
describe the atom as a positively charged nucleus surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with almost all of the mass in the nucleus
#P1.1c
recall the typical size (order of magnitude) of atoms and small molecules
knowledge that it is typically 1 × 10–10 m
#P1.1d
define density
#P1.1e
explain the differences in density between the different states of matter in terms of the arrangements of the atoms and molecules
#P1.1f
apply the relationship between density, mass and volume to changes where mass is conserved