Is Ni2S3 ionic or covalent?

The electronegativity difference between P and Cl is 0.8 using Pauling scale in the range of covalent with small ionic character bonds or polar bonding, since the number of paired electrons around P atom is 4 (3 shared and one unshared pair), the geometric structure of PCl3 molecule is pyramid, which means the electric dipoles of the three P-Cl bonds do not cancel each other with the net result that the molecular is polar.

It is covalent. But from its high melting point value it is clear that it forms crystal lattices and thus have some ionic character.

Look at the struture - chain with tetrahedra of O about the Cr - covalent.

As the oxidation state of the metal increases (radius decreases) its polarisability increases, leading to covalent bonding.

Look at the acid/base properties - an acidic oxide.

Here In is in +3 oxidation state which means charge is high and the radius is less. It satisfies the Fajans rule of covalency which states that for a covalent compound the cation should be smaller in size and anion should be larger in size. So that cation can polarise anion more easily thereby increasing the covalent nature.

Hence the compound is covalent.

The electronegativity difference is on the order of 0.5. It should be around 2.0 for a compound to be ionic, so the Ni-S bonds are probably polar covalent.

It's covalent as carbon is a non metal and also there is not much electronegativity difference between carbon and hydrogen

[math] ext{Dinitrogen tetroxide}[/math] is MOLECULAR, and COVALENT, and presents an interesting Lewis structure …. we have [math]34[/math] electrons, [math]17[/math] electron-pairs to distribute around 4 centres … and we typically employ charge separation … i.e. consider the MONOMER, [math]NO_{2}[/math], with 17 valence ELECTRONS…

[math]O=stackrel{+•}N-O^{-}[/math]

…the lone electrons on each nitrogen are conceived to pair up, i.e. give a [math]N-N[/math] bond in the dimer, [math]N_{2}O_{4}[/math] …

[math]^{-}O(O=)stackrel{+•}N+stackrel{•+}N(=O)O^{-} ightleftharpoons ^{-}O(O=)stackrel{+}N-stackrel{+}N(=O)O^{-}[/math]

The magnesium is a 2+ ion and the CO3 is a 2- ion with most of the negative charge on the oxygen atoms. But, the CO3 ion itself is covalent.

Phosphorous pentoxide is covalent, and molecular, and has the molecular formula [math]P_{4}O_{10}[/math]. It is the acid anhydride of phosphoric acid as shown…

[math]P_{4}O_{10}(s) + 6H_{2}O(l) ightarrow 4H_{3}PO_{4}(aq)[/math]

…the oxide is very commonly used as a drying agent for halogenated solvents…

PBr5 in the solid state is ionic with PBr4+ and Br- filling the lattice. In the gaseous form it is covalent. Similarly, PCl5 is ionic in its solid state, containing PCl6- & PCl4+. But in the gas phase it is covalent.

Hydrogen sulfide is covalent, AND molecular. And in aqueous solution, hydrogen sulfide acts as a weak Bronsted acid …

[math]H_{2}S(aq) + H_{2}O(l) ightleftharpoons HS^{-} + H_{3}O^{+}[/math]

…the equilibrium lies to the LEFT as we face the page…