Basic Concepts of Chemistry

Mole Definition: A mole is a quantity that contains 6.022 × 10²³ entities (Avogadro's number).
Molar Mass: The mass of one mole of a substance (g/mol), numerically equivalent to its atomic or molecular mass.
Conversions:
- Moles to grams: Moles = Mass (g) / Molar Mass (g/mol)
- Grams to moles: Mass (g) = Moles × Molar Mass (g/mol)
Empirical Formula: Simplest whole number ratio of elements in a compound.
Molecular Formula: Actual number of atoms of each element in a molecule.

Basic Parts of Atom:
- Protons (positive charge, located in nucleus)
- Neutrons (neutral charge, located in nucleus)
- Electrons (negative charge, orbiting nucleus)
Atomic Number (Z): Number of protons in an atom, determines element identity.
Mass Number (A): Total number of protons and neutrons.
Isotopes: Atoms of the same element with different numbers of neutrons.
Electron Configuration: Distribution of electrons in atomic orbitals (e.g., 1s² 2s² 2p⁶).

Atomic Radius:
- Decreases across a period (left to right) due to increased nuclear charge.
- Increases down a group due to increased electron shell number.
Ionization Energy:
- Increases across a period (more energy required to remove electrons).
- Decreases down a group (electrons are further from the nucleus).
Electronegativity:
- Increases across a period, decreases down a group.
- Measure of an atom's ability to attract electrons in a bond.
Metallic Character: Decreases across a period and increases down a group.

Definition: The calculation of reactants and products in chemical reactions based on balanced equations.
Balanced Chemical Equation: An equation with equal numbers of each type of atom on both sides.
Mole Ratios: Derived from coefficients in a balanced equation, used for conversions between reactants and products.
Limiting Reactant: Reactant that is consumed first, limiting the amount of product formed.
Percent Yield: Actual yield / Theoretical yield × 100%.

Ionic Bond: Formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions.
Covalent Bond: Formed by the sharing of electron pairs between atoms.
Metallic Bond: Attraction between metal ions and delocalized electrons.
Bond Polarity:
- Nonpolar Covalent: Equal sharing of electrons.
- Polar Covalent: Unequal sharing, resulting in partial charges.
VSEPR Theory: Predicts molecular shapes based on electron repulsion.

Matter: Anything that has mass and occupies space; can be classified as elements, compounds, and mixtures.
Physical Properties: Characteristics that can be observed or measured without changing the substance (e.g., color, boiling point).
Chemical Properties: Characteristics that determine how a substance reacts (e.g., flammability).
States of Matter: Solid, liquid, gas; changes in state are physical changes.
Chemical Reactions: Process where substances change into new substances, characterized by reactants and products.

A mole represents 6.022 × 10²³ entities, known as Avogadro's number.
Molar mass is expressed in grams per mole (g/mol) and equates numerically to atomic or molecular mass.
Converting between moles and grams involves:
- From moles to grams: Moles = Mass (g) / Molar Mass (g/mol)
- From grams to moles: Mass (g) = Moles × Molar Mass (g/mol)
The empirical formula indicates the simplest whole number ratio of elements in a compound.
The molecular formula provides the actual number of atoms for each element in a molecule.

Atoms consist of three fundamental parts:
- Protons carry a positive charge and reside in the nucleus.
- Neutrons have no charge and are also located in the nucleus.
- Electrons carry a negative charge and orbit around the nucleus.
The atomic number (Z) is defined as the number of protons and identifies the element.
Mass number (A) is the total count of protons and neutrons in an atom.
Isotopes are variants of the same element that differ in neutrons.
Electron configuration describes how electrons are arranged in atomic orbitals, exemplified by notation such as 1s² 2s² 2p⁶.

Atomic radius decreases across a period due to increased nuclear charge but increases down a group due to additional electron shells.
Ionization energy, the energy needed to remove an electron, increases across a period and decreases down a group.
Electronegativity rises across a period and decreases down a group, indicating an atom's ability to attract bonding electrons.
Metallic character diminishes across a period and enhances down a group.

Stoichiometry involves calculating quantities of reactants and products using balanced equations.
A balanced chemical equation has equal atom counts for each element on both sides.
Mole ratios derive from the coefficients of a balanced equation and facilitate conversions between reactants and products.
The limiting reactant is the substance that is completely consumed first, determining the maximum yield of products.
Percent yield is calculated as Actual yield / Theoretical yield × 100%.

Ionic bonding occurs through the transfer of electrons, forming oppositely charged ions.
Covalent bonding involves sharing electron pairs between atoms.
Metallic bonding is characterized by the attraction between metal ions and delocalized electrons.
Bond polarity is classified into:
- Nonpolar covalent bonds, where electrons are shared equally.
- Polar covalent bonds, where electrons are shared unequally, leading to partial charges.
VSEPR Theory predicts molecular shapes based on the repulsive behavior of electron pairs.

Matter is defined as any substance that has mass and occupies space, categorized into elements, compounds, and mixtures.
Physical properties can be observed or measured without altering the substance, including characteristics like color and boiling point.
Chemical properties dictate how a substance interacts in reactions, such as its flammability.
The states of matter include solids, liquids, and gases, with state changes representing physical alterations.
Chemical reactions transform substances into new entities, identified by reactants and products.