Final answer:
Gallium (Ga) is paramagnetic due to having an unpaired electron in its 4p orbital. Both Hg and Sr are diamagnetic, as they have no unpaired electrons. Be in its ground state and Be₂²- with an extra two electrons are both diamagnetic as well.
Step-by-step explanation:
To determine which atoms are paramagnetic in their ground state, we look at their electron configurations and see if there are any unpaired electrons. An atom or ion with unpaired electrons will be paramagnetic and will be attracted to a magnetic field, whereas if all electrons are paired, the atom or ion is diamagnetic and will be repelled by a magnetic field.
- Hg (Mercury): This is a heavy element with a filled electron subshells in its ground state, meaning it is likely to be diamagnetic.
- Ga (Gallium): Gallium has an electron configuration that ends in 4p¹. This unpaired 4p electron makes gallium paramagnetic.
- Sr (Strontium): Strontium's electrons are all paired in its ground state, making it diamagnetic.
- Be (Beryllium): In its ground state, beryllium's electron configuration is 1s²2s². All electrons are paired, hence beryllium is diamagnetic.
Now let's address the question about beryllium specifically. A Be₂²- ion would have the same electron configuration as beryllium in its ground state with an additional two electrons due to the 2- charge. These additional two electrons would pair up in the 2p orbital, so the Be₂²- ion would also be diamagnetic because it does not have any unpaired electrons.