and in the center of the cube (one more cation). Thus we have four anions (FCC) and four cations, which corresponds with the stoichiometry of the salt (1:1). occupying the tetrahedral holes. Remember ...

The relative ability of soils to store one particular group of nutrients, the cations, is referred to as cation exchange capacity or CEC ... it can be estimated from soil texture and color. Table 1 ...

The halogens are the elements in group 7 of the Periodic Table, and include chlorine, bromine and iodine. Their ions are called halide ions e.g. chloride, Cl-. You can test for them using silver ...