Answer:
NaCl= ionic bond.
H2O=covalent bond.
Step-by-step explanation:
NaCl:
Happens between metal and non-metal. since metal needs to lose an electron to get a full outer shell of electrons, sodium (Na) loses one electron and has a full outer shell of electrons.
chlorine is a gas so it needs to gain electrons to have a full outer shell. since it is in group 7, it needs to gain 1 electron for a full outer shell of electrons.
the lost electron from sodium is given to chlorine. this creates ions (a charged particle) so it is Na+Cl-. this creates a strong electrostatic attraction between the elements and causes them to join together in a lattice form.
H2O:
Covalent bonds happens between 2 gases. they share an electron or 2, and the bonds are very strong.
since oxygen needs 2 molecules to form a full outer shell. hydrogen have 1 atom in outer shell so they share the electron with the oxygen atom.
I can't fully explain why this is for H2O, but I hope you understand it.