What makes lodestones and synthetic magnets effective?

[Antigone]

What makes lodestones such good magnets? And what makes synthetic magnets "good"? Do magnets have subatomic particles arranged differently?

 

[SteamKing]

Google is your friend.

 

[hjelmgart]

I cannot comment on the lodestones, google would answer me as good as it would answer ýou. What do you think defines a "good" magnet?
Magnetism stems from the electrons and the spin direction of the electrons. You need at least to understand some basic principles in quantum mechanics to understand, how electrons contributes to magnetism, as well as the reason for permanent magnets (below certain temperatures), and magnetic domains (subatomic arrangement).

So both the strength of the magnetic field and the temperature, at which it can maintain the field are important for a magnet to be "good", as you would not have much use for a magnet with a large magnetic intensity, if it would lose its magnetic order above 200 kelvin.

You can make good synthetic magnets, because you know the theory to make the best properties for your magnet (depending on how you need to use it), so that is quite obvious, I would say.
The strongest magnets you have are electromagnets, which you can also google.

 

[jtbell]

A good keyword to search on is probably "ferromagnetism".