What two important differences are there in the properties of sigma and pi bonds, in terms of how they affect
the structure and reactivity of molecules?

A triple bond is one sigma and two pi bonds. A sigma bond is your basic head-on covalent bond, with the bond in line with the bonding orbitals. You can only ever have one sigma bond between any two atoms. A pi bond is a covalent bond between orbitals perpendicular to the bond direction, usually p-orbitals (never s).

answer; natural resources;

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.