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Will all combinations of metals and non-metals from ionic bond? why?
No. It depends on the difference in (EN) between the two .
Electronegativity is the tendency of a bonded atom to attract electrons to itself. If the difference is between 0.4 to 1.7, the bond is considered to be polar covalent. (https://www.chem.wisc.edu/deptfiles/genchem/sstutorial/Text7/Tx71/tx71.html)
The metal beryllium (Be) and the nonmetal chlorine (Cl) form a polar covalent bond, forming beryllium chloride (also called beryllium dichloride), ##"BeCl"_2"##. The electronegativity of Be is 1.57 and the electronegativity of Cl is 3.16. ##3.16-1.57=1.59##.
You can find a table of electronegativities at: https://en.wikipedia.org/wiki/Electronegativity