name as many elements that can form both + and - ionswith reasons pls!!!!!

All atoms are composed of and equal number of protons (in the nucleus) and electrons (orbiting around the nucleus). Apart from Hydrogen atoms, all atoms also contain Neutrons in their nuclei. Neutrons have no electric charge. Protons have a positive electric charge:

P +

and electrons have a negative electric charge:

e -

This means that if an atom has equal numbers of protons and electrons it will have no overall charge. When an atom loses an electron it must have more protons than electrons so it will have an overall positive charge: these are all positive ions. You will find these elements in the first column of the periodic table, this is Group I.

H⁺ , Li⁺, Na⁺ , K⁺,Be²⁺,Mg²⁺,Al³⁺  etc

So now have a look at Group VII. Here we find some more easy ones. The elements in Group VII all form ions with a single negative charge. This is because they contain one more electron than protons. Just to make you life a little more interesting (or difficult) chemists change the name of the substance to indicate whether it is an atom or ion they are talking about so Fluorine atoms can be turned into Fluoride ions by gaining one electron. Fluorine --- Fluoride, Chlorine --- Chloride, Bromine --- Bromide, Iodine --- Iodide, Sulphur --- Sulphide.

F^- , Cl^- , Br^- , I^-  etc