A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes

Medium

Describe the "plum pudding" model of the atom developed by J. J. Thomson.

[2]

List the three primary subatomic particles (electrons, neutrons, and protons) in chronological order of their discovery, from earliest to latest.

[1]

The existence of isotopes explains why the relative atomic masses of many elements are not whole numbers.

Element $Λ\Lambda$ has two stable isotopes. The table below shows the mass numbers and percentage abundances of the isotopes of element $Λ\Lambda$ .

Mass number	Percentage abundance (%)
85	72.2
87	27.8

Calculate the relative atomic mass ( $A_r$ ) of element $Λ\Lambda$ . Give your answer to 1 decimal place.

[2]

A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes Questions