Basic Concepts in Chemistry

Atoms: The basic unit of matter, consisting of protons, neutrons, and electrons.
- Proton: Positively charged, found in the nucleus.
- Neutron: Neutral charge, also in the nucleus.
- Electron: Negatively charged, orbits the nucleus.
Elements: Pure substances consisting of only one type of atom; represented by symbols (e.g., H for hydrogen).
Compounds: Substances formed from two or more different elements chemically bonded together (e.g., H2O for water).
Molecules: Two or more atoms bonded together, can be the same or different elements (e.g., O2 is a molecule of two oxygen atoms).

Chemical Bonds

Ionic Bonds: Formed by the transfer of electrons from one atom to another, resulting in charged ions (e.g., NaCl).
Covalent Bonds: Formed by the sharing of electron pairs between atoms (e.g., H2, where two hydrogen atoms share electrons).
Metallic Bonds: Atoms share a pool of electrons; characterized by conductivity and malleability.

States of Matter

Solid: Definite shape and volume; particles are tightly packed.
Liquid: Definite volume but no definite shape; particles are close but can move past one another.
Gas: No definite shape or volume; particles are far apart and move freely.

Chemical Reactions

Reactants and Products: Reactants are substances that undergo a chemical change, and products are the substances formed as a result.
Types of Reactions:
- Synthesis: Two or more reactants combine to form one product (A + B → AB).
- Decomposition: One reactant breaks down into two or more products (AB → A + B).
- Single Replacement: One element replaces another in a compound (A + BC → AC + B).
- Double Replacement: Exchange of ions between two compounds (AB + CD → AD + CB).
- Combustion: A substance reacts with oxygen, usually producing heat and light (typically involves hydrocarbons).

The Periodic Table

Groups: Vertical columns; elements share similar properties.
Periods: Horizontal rows; properties change progressively across the table.
Metals, Nonmetals, Metalloids: Categorization based on physical and chemical properties.

Acids and Bases

Acids: Substances that release hydrogen ions (H+) in solution; sour taste, pH < 7.
Bases: Substances that produce hydroxide ions (OH-) in solution; bitter taste, slippery feel, pH > 7.
Neutralization: Reaction between an acid and a base to form water and a salt.

Stoichiometry

The calculation of reactants and products in chemical reactions based on the balanced equation.
Mole: A fundamental unit in chemistry representing 6.022 x 10^23 particles.

Thermochemistry

Study of heat change during chemical reactions.
Endothermic Reactions: Absorb heat (temperature decreases).
Exothermic Reactions: Release heat (temperature increases).

Solutions

Solute: Substance that is dissolved (e.g., salt).
Solvent: Substance that does the dissolving (e.g., water).
Concentration: Amount of solute in a given volume of solvent; commonly expressed in molarity (M).

Key Concepts in Bonding and Structure

Electronegativity: Measure of an atom's ability to attract electrons in a bond; affects bond type.
Polar vs. Nonpolar Molecules: Polar molecules have uneven distribution of charges; nonpolar molecules have even distribution.

Laboratory Safety

Always wear personal protective equipment (PPE).
Understand the material safety data sheets (MSDS) for chemicals being used.
Properly label and store chemicals; follow disposal guidelines.

Basic Chemistry Concepts

Atoms: Tiny building blocks of everything. They consist of a nucleus containing positively charged protons and neutral neutrons, surrounded by negatively charged electrons orbiting the nucleus.
Elements: Unique pure substances made up of only one type of atom, like hydrogen (H) or oxygen (O). Each element has a unique symbol.
Compounds: Substances formed from two or more different elements chemically combined, like water (H₂O) or salt (NaCl).
Molecules: Groups of two or more atoms held together by chemical bonds, which can be made up of the same or different elements, like oxygen gas (O₂) or carbon dioxide (CO₂).

Chemical Bonds

Ionic Bonds: Form when electrons are transferred between atoms, creating oppositely charged ions that attract each other. For example, in table salt (NaCl), sodium (Na) loses an electron to become a positive ion (Na⁺), while chlorine (Cl) gains an electron to become a negative ion (Cl^-), forming a strong attraction.
Covalent Bonds: Form when atoms share electrons, creating a strong bond between them. For example, in a water molecule (H₂O), two hydrogen atoms share electrons with a single oxygen atom, forming a stable molecule.
Metallic Bonds: Found in metals, where electrons are shared freely among the metal atoms, allowing for good electrical conductivity and malleability.

States of Matter

Solids: Have a fixed shape and volume because their particles are tightly packed and vibrate in place.
Liquids: Have a fixed volume but take the shape of their container because particles are closer together but can move around each other.
Gases: Have no fixed shape or volume and expand to fill their container because particles are far apart and move freely.

Chemical Reactions

Reactants and Products: Reactants are the starting materials that transform into products during a chemical reaction.
Types of Reactions:
- Synthesis: Two or more reactants combine to make one product (A + B → AB).
- Decomposition: One reactant breaks down into two or more products (AB → A + B).
- Single Replacement: One element replaces another in a compound (A + BC → AC + B).
- Double Replacement: Ions from two compounds switch places (AB + CD → AD + CB).
- Combustion: A substance reacts rapidly with oxygen, releasing heat and light, often involving hydrocarbons.

The Periodic Table

Groups: Vertical columns containing elements with similar chemical properties.
Periods: Horizontal rows, arranged in increasing atomic number, where properties change gradually across the table.
Metals, Nonmetals, Metalloids: Categories defined by their physical and chemical properties, like luster, conductivity, and reactivity.

Acids and Bases

Acids: Substances that release hydrogen ions (H⁺) in solution, typically having a sour taste and a pH less than 7.
Bases: Substances that produce hydroxide ions (OH^-) in solution, usually having a bitter taste, slippery feel, and a pH greater than 7.
Neutralization: A reaction between an acid and a base that produces water and a salt.

Stoichiometry

Involves calculating the amounts of reactants and products in a chemical reaction using a balanced chemical equation.
Mole: A fundamental unit in chemistry representing 6.022 x 10²³ particles (atoms, molecules, etc.).

Thermochemistry

Study of heat changes that occur during chemical reactions.
Endothermic Reactions: Absorb heat from the surroundings, causing a temperature decrease.
Exothermic Reactions: Release heat into the surroundings, causing a temperature increase.

Solutions

Solute: Substance that gets dissolved (e.g., sugar in water).
Solvent: Substance that does the dissolving (e.g., water).
Concentration: Measures the amount of solute in a given volume of solvent; often expressed in molarity (M), moles of solute per liter of solution.

Key Concepts in Bonding and Structure

Electronegativity: A measure of an atom's ability to attract electrons in a chemical bond. Differences in electronegativity between atoms determine the type of bond formed (ionic, covalent, polar covalent).
Polar vs. Nonpolar Molecules: Polar molecules have uneven distribution of electron density, resulting in partial charges. Nonpolar molecules have even distribution of electron density.

Laboratory Safety

Personal Protective Equipment (PPE): Wear gloves, goggles, lab coat, and closed-toe shoes, as appropriate.
Material Safety Data Sheets (MSDS): Understand the hazards associated with chemicals and how to handle them safely.
Storage and Disposal: Always label and store chemicals properly, follow disposal guidelines, and seek guidance from instructors if needed.