Midterm 2 concepts

Polar Bonds result from

unequal electronegativity values

Dipole movement arrow

Indicates direction of polarity, points towards the more electronegative atom where negative density pulls

Breaking and forming bonds are (individually) exothermic or endothermic?

breaking is endothermic, forming is exothermic

Atomic size dictates ___

atomic size dictates bond length – Bigger atom means longrer bonds

Bond order & trends (bond energy/length as bonds increase)

The number of bonds shared between two atoms

Bond energy increases as length decreases (ONLY when comparing the same pair of elements across different molecules)

Bond length decreases as bond order decreases

Covalent Nomenclature Rules and prefixes

more electropositive element goes first, more electronegative comes second and ends in “ide”

Greek prefixes are used for the number of atoms (but you don’t use mono on the first element)

ex: dinitrogen pentoxide

Acid definition and Acid Nomenclature

(and nomenclature without oxygen)

Acid: covalent molecules that have hydrogen attached, but when placed into water ionize

“-ate” becomes “-ic acid”

“-ite” becomes “-ous acid”

When theres no oxygen present = “hydro…-ic acid”

Duet rule

Hydrogen and Helium only need 2 electrons to fill their 1s orbital

A lone pair of electrons has ____ repulsion than bonded

Greater

Resonance Forms

• A true structure is a weighted average of 2+ Lewis dot structures

• Valid resonance forms have the same # of electrons and full octets but are different due to interchanged multiple bonds/lone pairs

• all atoms in exact same positions

• resonance forms may be equivalent (identical in stability and formal charges) or inequivalent

Theoritical, Actual, Experimental yield

• Theoretical yield - the amount of product expected

• actual - real amount obtained

• experimental % yield: (actual yield)/(Theoretical yield) * 100

Ion stabilization in solid/solvated states

Bare ionic charges are not electrically stable

• in solid state, opposite charges stabilize one another

• when solvated, the ions are stabilized with interactions with solvent dipoles (usually water) (hydration shells)

Strong electrolytes (behavior, conductivity, types)

• completely ionize in solution (100% of compound splits into free-floating electrons)

• high conductivity

• Soluble salts (ionic compounds with low charges [+1/-1, +2/-1])

• strong acids HCl, HBr, HI, HNO₃, HClO₄, HClO₃, & H₂SO₄

• strong bases (group 1 and 2 hydroxides)

Weak electrolytes (behavior, conductivity, types)

• partially ionize in solution (<5%)

• weak conductivity due to presence of few ions

• all acids that are not strong and all bases that are not hydroxide

Ionization

To ionize means a neutral molecule splits apart or reacts to produce charged ions (+ and - ) that can float freely in water.

Strong vs Weak electrolyte dipole/ion movement

for strong acids and bases, (and weak salts) the water's dipoles (positive hydrogen and negative oxygen) will surround the individual ions since the ions are really strong, completely splitting them apart into smaller charged ions.

for weak acids and bases, the acid/base molecules have to give or take an H+ ion to/from water, making either (OH-) or H_3O+ (aka H+), forming two seperate ions using water. The newly created ions are now swarmed by water!

identifying Strong bases Vs. Weak bases Vs. Soluble salts

Strong base:

• Metal + Hydroxide (OH-), Group 1 and 2 metals

Weak base:

• Covalent Nitrogen compounds (NH₃, NO₂⁻) or weak acid anions

Soluble salt:

• Metal + nonmetal (with relatively low charges)

Acid Vs Base

Acids are proton donors, release/donate H+ into water to increase H+ (H₃O⁺)

Bases are proton acceptors, either drops OH- directly into solution or takes H+ from water to make OH-

Molecular Vs. Full Ionic Vs. Net Ionic Equations

Molecular: shows all species/everything present and does not seperate ions (with phase)

Full Ionic: shows all species & seperates everything aqueous in solution into soluble ions (know solubility rules

Net Ionic: Shows only reactive species (any ions on both sides of the full ionic equation cancel out- spectator ions)

Arrhenius Acid/BAse

Arrhenius acid- generates H+ in an aqueous solution
Arrhenius base- generates OH- in an aqueous solution

Bronstead Lowry acid/base

Bronstead Lowry acid: H+ donor

Bronstead Lowry base: H+ acceptor

Neutralization reaction

The combination of an acid and a base always generates a salt (ionic substance) and usually produces water as well.

Oxidation Number rules

• Atoms in pure elements are 0

• Atoms in ions have #s equal to their ionic charge

• In binary compounds/polyatomic ions, the more electronegative atom has an oxidation number based on its common valence

• all atoms of the element in a compound/ion have the same oxidation #

• Group ½ atoms always have oxidation numbers +1/+2 respectively

• Oxygen is always -2, unless its with a peroxide (having a single covalent bond connecting two oxygen atoms, eg H₂O₂)

• Hydrogen is always +1 unless paired with a metal (then it’s -1)

When strong acids + bases meet in a solution, it results in what? what does it produce? With what?

A neutralization reaction, which always produces water and a salt.
the salt is made from the cation of the base and anions left over from the acid

Driving force in aqueous ionic reactions (or double displacement reactions)!

the removal of ions from aqueous

solution through the formation of a solid, liquid, or gas