Polonium lose electrons.
The atom is neutral; the cations of Po are of course positive. Polonium lose electrons.
Phosphorus wants to gain three electrons to have 8 valence electrons.
Barium loses 2 as it is in group 2 and it's easier to lose two than to gain more than this.
Sodium (Na) tends to lose electrons to achieve a full outer electron shell, which allows it to reach a stable electron configuration. This results in Na forming a +1 cation.
Beryllium will lose 2 electrons when forming an ion because it has 4 valence electrons and tends to reach a stable electron configuration by losing electrons to achieve a full outer shell.
The atom is neutral; the cations of Po are of course positive. Polonium lose electrons.
Polonium will neither gain nor lose electron. it will prefer to form covalent compounds by sharing of electrons.
Polonium can lose two or four electrons.
Compounds will gain or lose electrons in order to reach a more stable state, ideally a full valence shell.
Phosphorus wants to gain three electrons to have 8 valence electrons.
Lose
When atoms lose or gain electrons, they form ions. These are charged particles.
Se will gain electrons
Lose electrons is oxidation. To gain electrons is reduction.
Silicon (Si) can gain or lose 4 electrons. It can either gain 4 electrons to have a stable octet configuration or lose 4 electrons to achieve a stable configuration.
If you mean Metals... No, they do not gain electrons, they actually lose electrons because it is a lot easy for them to lose them so they can gain stability much faster.
Barium loses 2 as it is in group 2 and it's easier to lose two than to gain more than this.