Covalent bond and ionic bond

Covalent bond is formed by sharing of electrons between non-metals while ionic bond is formed by transfer of electron(s) from non-metal to metal.

H2O molecules are linked by weak hydrogen bonding, much lower boling point at 100 deg C, compared with NaCl about 1413 deg C.

The ionic structure is linked by strong ionic bond. Refer to the smallest unit, the unit cell, just imagine each ion is at centre of cube and therefore surrounded by 6 opposite charge ions.

covalent bond and ionic bond係一個model去解釋bonding......唔好對佢咁認真....(不過你考試CE/AL就唔好對我呢句咁認真....會冇分ga)
1.
H+同O2-都唔stable,而且pure water唔可以導電,咁你都知佢ionic character幾弱...
2.
因為佢係solid.....from到solid就一定要有個3D structure,可以係crystalline/amorphous (or in between)得一粒Na&Cl就form唔到一個我地可以analyze到的東西.......
個packing同size&charge有關