# BeF2 : covalent or ionic?

My textbook says despite large electronegativity difference it's covalent since beryllium ion will have too much charge density and it'll attract fluorine election cloud and therfore forms polar covalent bound.

But I looked it up in Wikipedia and found out that it has a crystal lattice, is Soluble in water and has a quiet high melting point.

What else one needs to call a compound ionic? Am I or the textbook right?

• I am not putting this as an answer but bond between 2 different atoms is usually not completely covalent nor completely ionic: it is a mixture of them. We prefer to talk about the "covalent" or the "ionic" character of a bond. – SteffX Aug 9 '16 at 19:13
• And BeF2 probably has more ionic then covalent character, not that it matters much. – Mithoron Aug 9 '16 at 19:16
• Nearly anything has a crystal lattice. Many covalent compounds are soluble in water (and quite a few ionic ones are insoluble). As for the melting point, well, it's moderately high, so consider $\ce{BeF2}$ moderately ionic and stop pursuing this false dichotomy. Also, I suggest to close this question as a duplicate of AlCl3: ionic and covalent?, because though the title compounds are different, just about every argument applies equally well to both. – Ivan Neretin Aug 9 '16 at 19:40
• – Mithoron Aug 9 '16 at 20:31
• @IvanNeretin "All bonds to fluorine, with the exception N-F, O-F, and F-F, have considerable ionic character, so the vast majority of AFn molecules are more appropriately described in terms of an ionic model rather than a covalent model." pubs.acs.org/doi/abs/10.1021/ic961315b BeF2 is much more extremely ionic than AlCl3 , with Be having a +1.8 charge. The AlCl3 answer does not apply well to BeF2. – DavePhD Aug 10 '16 at 13:02