[3] Use o to represent an electron from a calcium atom. Cations and anions are both ions. Halogens always form anions, alkali metals and alkaline earth metals always form cations. Examples include calcium chloride (CaCl 2), potassium iodide (KI) and magnesium oxide (MgO). 3 Calcium reacts with nitrogen to form the ionic compound calcium nitride, Ca 3 N 2. Source(s): calcium nitride written ca3n2 can2 ca2n3: https://tinyurl.im/pUeNu It exists in various forms (isomorphs), α-calcium nitride being more commonly encountered. Use x to represent an electron from a nitrogen atom. Write the symbol and charge of the cation (metal) first and the anion (nonmetal) second. Why calcium nitride written like Ca3N2 and not something like CaN2 or Ca2N3? In other words why do exactly three calcium ions bond with exactly two nitride ions? It can be possible to predict whether an atom will form a cation or an anion based on its position on the periodic table. (a) Draw a diagram, based on the correct formula, which shows the charges on the ions and the arrangement of the electrons around the negative ion. Write the formula for calcium nitrate; 1. 3. The difference between a cation and an anion is the net electrical charge of the ion . \(\ce{Ca^{2+}} \: \: \: \: \: \ce{NO_3^-}\) 2. Structure. Calcium nitride is the inorganic compound with the chemical formula Ca3N2. Current Location > Formulas in Chemistry > Chemistry (Basics) > Cations and Anions Cations and Anions Don't forget to try our free app - Agile Log , which helps you … Transpose only the number of the positive charge to become the subscript of the anion and the number only of the negative charge to become the subscript of the cation. Ions are atoms or molecules which have gained or lost one or more valence electrons , giving the ion a net positive or negative charge. Since Calcium is +2 and Nitride is -3 the only way to balance them is to have three Calcium's and two nitrides ... Once you have determined the number of units of the cation and anion those become the subscripts which are placed right after the respective symbol. α-Calcium nitride adopts an anti-bixbyite structure, similar to Mn 2 O 3, except that the positions of the ions are reversed: calcium (Ca 2+) take the oxide (O 2−) positions and nitride ions (N 3−) the manganese (Mn 3+).In this structure, Ca 2+ occupies tetrahedral sites, and the nitride centres occupy two different types of octahedral sites. Cation vs anion periodic table.