omahaspot.blogg.se - Lattice energy trend periodic table compounds

Saturated Unsaturated and Supersaturatedīond Length is the average distance between the two nuclei of atoms bonded together in a covalent bond.Reaction Quotient and Le Chatelier's Principle.The table below shows the trend in electron affinities. Prediction of Element Properties Based on Periodic Trends Ionic compounds form because metals want to give up valence electrons and nonmetals want to gain.Molecular Structures of Acids and Bases.Ion and Atom Photoelectron Spectroscopy.Elemental Composition of Pure Substances.Application of Le Chatelier's Principle.Structure, Composition & Properties of Metals and Alloys.Intramolecular Force and Potential Energy.

Variable Oxidation State of Transition Elements.

Transition Metal Ions in Aqueous Solution.

Single and Double Replacement Reactions.

Factors that affect lattice energy trend The strength of the ionic bond increases with the increase of lattice energy. Because of this, the lattice energy keeps rising as well.

Fe 3 +: Perchlorate is soluble, but sulfate is insoluble.ĥ) Multiple charged anions such as O 2-, S 2-, PO 4 3 -, and SO 4 2 - make insoluble salts with most M 2+, M 3+, and M 4+ metals. As we move across a period, the charge on ions like K+, Ca2+, Ga3+, etc., increases.

Ln 3 +: Nitrate salts are soluble, but oxides and hydroxides are insoluble.

For example, AgF, AgCl, AgBr, and AgI exhibit progressively lower solubility because of increasing covalency.ģ) Increasing the charge on the anion lowers the solubility because the increase in E L is large relative to the increase in E H.Ĥ) Small, polyvalent cations (having large E H) make soluble salts with large, univalent anions such as I -, NO 3 -, ClO 4 -, PF 6 -, and acetate.Įxamples: Salts of transition metal and lanthanide ions

The similarity in size of the two ions contributes to the low solubility of BaSO 4 in water.Ĭombining all our conclusions about solubility, we note the following trends:ġ) Increasing size mismatch between the anion and cation leads to greater solubility, so CsF and LiI are the most soluble alkali halides.Ģ) Increasing covalency leads to lower solubility in the salts (due to larger E L. Space-filling models showing the van der Waals surfaces of Ba 2 + and SO 4 2. Putting both trends together, we see that low solubility is most often encountered when the anion and cation match well in their sizes, especially when one or both are multiply charged. For fluorides and hydroxides, LiF is slightly soluble whereas CsF is very soluble, and Mg(OH) 2 is insoluble whereas Ba(OH) 2 is very soluble. Anion-cation size mismatch occurs with larger cations, such as Cs + and Ba 2 +, which make soluble fluoride salts.įor small anions, E L is more sensitive to r +, whereas E H does not depend on r + as strongly. Right: In the case of small anions such as F - and OH -, the lattice energy dominates with small cations such as transition metal ions (TM n +), Mg 2 +, and Li +. With larger cations such as Ba 2 +, which have lower E H, the lattice energy exceeds the solvation enthalpy and the salts are insoluble. The large SO 4 2 - ion is size-mismatched to small cations such as Mg 2 +, which have large hydration energies, resulting soluble salts. On the other hand, E H changes substantially with r +, especially for small cations.Īs a result, sulfate salts of small divalent cations, such as MgSO 4 (epsom salts), are soluble, whereas the lower hydration energy of Ba 2 + in BaSO 4 makes that salt insoluble (K sp = 10 -10). That is because the anion dominates the r + + r - term in the denominator of the formula for E L.

\]įor salts that contain large anions, E L doesn't change much as r + changes.