General Chemistry 162 Notes

Significant Figures in Calculations

Recall that trailing zeros (zeros after a decimal) are significant. Calculation of sig fig is different for add/sub and multiplication/divison

Types of Chemical Bonds

Ionic Bond: Nonmetal + Metal

Nonmetal gain electrons(anion) while Metal lose electrons(cation) via transfer. These bonds form ionic compounds

Covalent Bond: Nonmetal + Nonmetal

The bond between two or more nonmetals via sharing. These bonds form molecular compounds

Ions & Polyatomic Ions (Do Not Confused w/ ionic bonds)

Ions(monoatomic): a neutral atom gains or loses electrons. Any element with a charge ±

NO BONDS because it is one element (Ex: Na^+, Cl^-)

Multiple ions (polyatomic ions): Two or more atoms covalently bonded elements with an overall charge of +\-

Ex: SO4^-2

Application:

Na⁺ + OH⁻

Na⁺ is a monatomic ion.

OH⁻ is a polyatomic ion.

The attraction between Na⁺ and OH⁻ is ionic.

But the bond inside OH⁻, between O and H, is covalent. Aka polyatomic ions. (Must have charge overall in the atoms unlike ionic bonding)

Ex: NaOH although both have charges pos and neg. It is an ionic bond/ ionic compound because it is nonmetal + metal, AND it doesn’t have an overall charge like all polyatomic ions do.

Moles, mol, molecules

Mole concept: Mole is a chemist dozen. It is the amount of material containing 6.022 × 10^23 particles/atoms etc. (Avogadro’s Number)

Mol: The abbreviation of mole

Molecules: Two or more atoms joined chemically (covalent bonding) in a specific geometrical arrangement. Ex: H2O, O2

Chapter 13 Solutions

The next key terms and concepts will be part of chapter 13

Solution Concentration

Solution: Homogeneous mixture of two substances (either ionic or covalent)

Solvent: Major component of solution

Solute: Minor component of solution

Aqueous solution: Whenever water is the solvent.

Molarity, Concentration, Dilute

Molarity(M): the amount of solute (in mol) divided by volume of solution (in liters)

Concentration: Large amount of solute

Dilute: Small amount of solute

Exothermic & Endothermic

Endothermic: absorbs heat from its surroundings (+)

Exothermic: describes a process that releases heat to its surroundings (-)

The change of heat in solute and solvent are both endothermic (+) while the change of heat in a mixture is exothermic (-)

Expressing Solution Concentrations (IMPORTANT!)

Common ways of reporting solution concentration include molarity, molality, parts by mass, parts by volume, mole fraction, and mole percent.

Molality vs. Molarity

A concentration unit that is independent of temperature is molality (m). it is the amount of solute (in moles) divided by the mass of solvent (in kilograms)

Molarity (M) depends on volume and temperature. It is the amount of solute (in moles) divided by the volume of solution (in slithers (L))

Colligative Properties

A colligative property is a property that depends on the number of particles dissolved in solution, not on the type of particle. (Moreover the identity of the substance does not matter. If they have the same num of particles, they have the same effect)

The four colligative properties:

• Vapor Pressure Lowering

• Freezing Point Depression

• Boiling Point Elevation

• Osmotic Pressure

Van’t Hoff factor (i)