Atoms typically do not lose protons because that would change the identity of the element. Instead, atoms can lose or gain electrons to form ions with a different charge. Protons are not generally lost by atoms in chemical reactions.
Argon is a Noble Gas. Thus it does not lose or gain electrons.
Iron can both gain and lose electrons depending on the reaction it is involved in. In general, iron tends to lose electrons to form positively charged ions, such as Fe2+ or Fe3+, but it can also gain electrons to form negatively charged ions, such as Fe2-.
When atoms gain or lose electrons, they become negatively charged if they gain electrons (anions) or positively charged if they lose electrons (cations). These charged atoms are known as ions.
Aluminum typically loses 3 electrons to form a 3+ cation.
Beryllium tends to lose two electrons to form a 2+ cation.
The electro negativity of O is higher. So Beryllium loses 2 electrons.
Beryllium will lose 2 electrons to satisfy the octet rule (to fill its outer shell).
Beryllium has the electronic configuration 2, 2, so it is likely to lose two electrons, giving it the Helium configuration. However, in practice, beryllium compounds have a high degree of covalent character as the beryllium ion is small and very polarising.
Beryllium would tend to lose its two electrons when forming a bond because it is easier to lose its two valence electrons rather than gain an additional five in order to obtain a full outer shell.
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.
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.