General Chemistry Lecture Notes - Matter, Measurements, and Reactions

Comprehensive flashcards covering introductory General Chemistry topics including matter classification, measurement, atomic/molecular structure, stoichiometry, thermodynamics, electrochemistry, gas laws, and physical states.

Chemistry

The study of composition, structure, properties, and reactions of matter and the changes it undergoes.

Matter

Anything that occupies space and has mass.

Pure Substance

A substance that has a definite composition and distinct properties.

Mixture

A combination of two or more substances in which the substances retain their distinct identities.

Homogeneous Mixture

A mixture in which the composition is the same throughout.

Heterogeneous Mixture

A mixture in which the composition is not uniform.

Element

A substance that cannot be separated into simpler substances by chemical means.

Compound

A substance composed of two different elements or more chemically united in fixed proportions.

Physical Property

A property that can be measured and observed without changing the composition or identity of a substance; examples include color, mass, and size.

Chemical Property

A property observed when matter undergoes a chemical change or reaction; examples include reactivity and flammability.

Extensive Property

A property that depends on how much matter is being considered.

Intensive Property

A property that does not depend on how much matter is being considered.

Mass

A measure of the amount of matter in an object, typically measured in grams ($g$) or kilograms ($kg$).

Weight

The force that gravity exerts on an object, measured in Newtons ($N$).

Density

The mass per unit volume of a substance, defined by the formula $d = \frac{m}{V}$.

Precision

How close a set of measurements are to each other (reproducibility).

Accuracy

How close measurements are to the true value.

Molar Mass (Atomic Weight)

The mass of an element's atoms per one mole ($g/mol$).

Mole (mol)

The amount of a substance that contains as many elementary particles (atoms, molecules, or ions) as there are atoms in exactly $12$ g of $^{12}C$, which is $6.022 \times 10^{23}$ particles (Avogadro’s number).

Empirical Formula

A formula showing the simplest whole-number ratio of the atoms in a substance.

Molecular Formula

A formula showing the exact number of atoms of each element in the smallest unit of a substance.

Solution

A homogeneous mixture of two or more substances.

Solute

The substance that is being dissolved in a solution, usually present in the smaller amount.

Solvent

The substance which dissolves a solute, usually present in the larger amount.

Molarity (M)

The number of moles of solute dissolved in one liter of solution.

Molality (m)

The number of moles of solute dissolved in one kilogram of solvent.

Stoichiometry

The quantitative study of reactants and products in a chemical reaction.

Energy

The capacity to do work.

Open System

A system that can exchange both mass and energy with its surroundings.

Closed System

A system that allows the transfer of energy (heat) but not mass.

Isolated System

A system that doesn't allow the transfer of either mass or energy.

Exothermic Process

Any process that gives off heat and transfers thermal energy from the system to the surroundings.

Endothermic Process

Any process in which heat has to be supplied to the system from the surroundings.

Hess’s Law

States that when reactants are converted to products, the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps.

Oxidation

A half-reaction that involves the loss of one or more electrons ($e^-$).

Reduction

A half-reaction that involves the gain of one or more electrons ($e^-$).

Anode

The electrode at which oxidation occurs.

Cathode

The electrode at which reduction occurs.

Boyle’s Law

States that the pressure of a fixed amount of gas at constant temperature is inversely proportional to its volume ($P_1V_1 = P_2V_2$).

Charles’ Law

States that the volume of a fixed amount of gas at constant pressure is directly proportional to its absolute temperature ($\frac{V_1}{T_1} = \frac{V_2}{T_2}$).

Avogadro’s Law

States that the volume of a gas at constant temperature and pressure is directly proportional to the number of moles of gas ($\frac{V_1}{n_1} = \frac{V_2}{n_2}$).

Ideal Gas Law

The general equation combining the gas laws, expressed as $PV = nRT$.

STP (Standard Temperature and Pressure)

Conditions characterized by a standard pressure of $1 \text{ atm}$ and a standard temperature of $273 \text{ K}$ ($0 \text{ }^\text{o}\text{C}$).

Dalton’s Law of Partial Pressures

States that the total pressure of a mixture of gases is the sum of the partial pressures of the individual components ($P_{total} = P_A + P_B + ...$).

Viscosity

The resistance to flow exhibited by all liquids and gases.

Hydrogen Bonding

An attractive force between a hydrogen atom covalently bonded to a very electronegative atom ($N$, $O$, or $F$) and a lone pair of electrons on another electronegative atom.

Crystalline Solid

A solid composed of one or more crystals that have a well-defined, ordered structure in three dimensions.

Amorphous Solid

A solid that has a disordered structure and lacks the well-defined arrangement of basic units found in a crystal.