What is a chemical bond? How are ions formed?
Chemicals bonds are atoms sticking together. Ions are formed when an atom gains or loses electrons and so gets a negative or positive charge, making it stick to other ions in an ionic bond.
Atoms are simply protons and neutrons in the middle with electrons orbiting around the outside. Protons are positive and electrons are negative, like the North and South ends of a magnet, and so attract. Neutrons are like lumps of rock, and are just there to make up space.
When atoms bond, they do so in order to gain or lose electrons so that their outer shells (electrons are arranged in shells, from the inside to out, like rings on a tree). The innermost shell is small so can have 2 electrons, the other shells can have 8 (except when you get to transition metals or the lanthanides and actinides, which act weirdly and have more)
In covalent bonding, between two non-metals, electrons are shared, and are in the orbit of both atoms, completing their outer or valence shells. 'Covalent' literally means 'with valence', because the outer shells of all the atoms are together.
In metallic bonding, the extra electrons of the metal atoms, like iron, form a sea of negative electrons, and the positive nuclei (protons and neutrons) are attracted to the negative sea. Because the electrons are relatively free, not belonging to any atom in particular, they can move around and conduct things like heat and electricity.
Ions are formed by one atom actually donating or giving electrons away to others. If sodium gives away the 1 electron in its outer shell to chlorine, which already has 7, then sodium is left with an empty valence shell and chlorine has a full one. However, the empty valence shell no longer exists, because it is empty, and so you look at the next shell down as the new outer shell, which is full.
Now sodium has lost an electron and chlorine has gained one, and since electrons are negative, sodium has become more positive and chlorine has become more negative. Like North and South on a magnet, they now attract each other, and form an ionic bond from sodium and chlorine ions. Ionic bonding only happens between non-metals and metals - the metals give electrons, the non-metals receive, so metals form positive ions, and non-metals negative.