Two elements have similiar characteristics when they belong to the same family that means that have placed in the same column of the periodic table. So in other words, Helium and Radon are very similar because they are in the same column. Let me know if you need others :)
Answer: See below
Explanation: a. The mass of an element is composed of:
protons: 1 amu each
neutrons: 1 amu each
electrons: 0 amu each
Only the protons and neutrons are counted in the atomic mass of an element
b. Electrons are assigned a mass of 0. They do have a mass, but it is exceedingly small compared to the protons and neutrons, so they are left out of the calculation of an element's mass.
c. An element becomes unstable if the neutrons exceed the protons by a certain ratio, dependent on the element.
To determine whether an element is paramagnetic or diamagnetic, you need to examine the electron configuration of the element. If it has unpaired electrons, then the substance is paramagnetic. If the electrons are paired, then it is diamagnetic.
