Electromagnets work by inducing a magnetic field in a material, which then allows the magnet to attract it. This only works for ferromagnetic materials, which are materials that can be easily magnetized.

Here are the metals that cannot be picked up by electromagnets:

* Non-magnetic metals:

* Gold (Au)

* Silver (Ag)

* Copper (Cu)

* Aluminum (Al)

* Lead (Pb)

* Titanium (Ti)

* Tin (Sn)

* Nickel (Ni) (while nickel is technically ferromagnetic, it is not as easily magnetized as iron and can be tricky to pick up)

* Other materials:

* Plastic

* Wood

* Glass

* Ceramics

Here are the metals that can be picked up by electromagnets:

* Iron (Fe)

* Cobalt (Co)

* Nickel (Ni) (although it's less easily magnetized than iron)

* Some alloys containing high amounts of iron, cobalt, or nickel

Important note: Even within ferromagnetic metals, the strength of the electromagnet and the size and shape of the object will influence whether or not it can be picked up.