1. Which of the following are properties of compounds formed by ionic bonding? Select all that apply:

lonic compounds have lower melting points than covalent compounds.

Ionic compounds form when combining a metal atom with a non-metal atom.

lonic compounds form when combining a two metal atoms.

lonic compounds form when combining two or more non-metal atoms.

When you dissolve an ionic compound in water, the solution conducts electricity.

When you dissolve an ionic compound in water, the solution does not conduct electricity

lonic compounds have higher melting points than covalent compounds.

pure substance: iron,copper

impure substance: water,charcoal

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.