Introduction to Chemistry: Matter and Its Properties

• Chemistry is the study of matter and its properties as well as how matter changes.
• Matter is anything that has mass and takes up space.

Branches of Chemistry

• Analytical chemistry studies the composition of matter.
• Organic chemistry studies carbon-containing compounds.
• Inorganic chemistry studies substances that do not contain carbon.
• Physical chemistry studies the physics of chemical systems.
• Biochemistry studies chemical processes in living organisms.

States of Matter

• Solid: Has a definite shape and volume; particles are tightly packed.
• Liquid: Has a definite volume but takes the shape of its container; particles are close but can move around.
• Gas: Has no definite shape or volume; particles are widely spaced and move freely.
• Plasma: An ionized gas with high energy.

Chemical Properties

• Describe how a substance changes into a new substance.
• Flammability: Ability to burn.
• Corrosiveness: Ability to corrode or rust.
• Reactivity: How readily a substance combines chemically with other substances.

Physical Properties

• Characteristics that can be observed without changing the substance.
• Boiling point: Temperature at which a liquid turns into a gas.
• Melting point: Temperature at which a solid turns into a liquid.
• Density: Mass per unit volume.
• Color: Visual appearance.

Chemical Changes

• Involve the formation of new substances.
• Burning: A substance reacts with oxygen to produce heat and light.
• Rusting: Iron reacts with oxygen and water to form iron oxide.
• Cooking: Applying heat to food causes chemical reactions.

Physical Changes

• Do not involve the formation of new substances.
• Melting: Solid to liquid.
• Boiling: Liquid to gas.
• Freezing: Liquid to solid.
• Dissolving: A substance mixes evenly in another.

Elements

• Pure substances that cannot be broken down into simpler substances by chemical means.
• Represented by chemical symbols (e.g., H for hydrogen, O for oxygen).
• Organized in the periodic table.

Compounds

• Substances composed of two or more elements chemically combined in fixed proportions.
• Can be separated into simpler substances only by chemical means.
• Examples include water (H2O) and sodium chloride (NaCl).

Mixtures

• Combinations of two or more substances that are physically combined.
• Components retain their individual properties.
• Can be separated by physical means.

Homogeneous Mixtures

• Have uniform composition throughout.
• Examples include salt water and air.

Heterogeneous Mixtures

• Do not have uniform composition.
• Examples include sand and water.

Atoms

• The smallest unit of an element that retains the chemical properties of that element.
• Consist of protons, neutrons, and electrons.

Protons

• Positively charged particles located in the nucleus.
• Determine the atomic number of an element.

Neutrons

• Neutrally charged particles located in the nucleus.
• Contribute to the mass of the atom.

Electrons

• Negatively charged particles that orbit the nucleus.
• Involved in chemical bonding.

Atomic Number

• The number of protons in the nucleus of an atom.
• Identifies an element.

Mass Number

• The total number of protons and neutrons in the nucleus of an atom.

Isotopes

• Atoms of the same element with different numbers of neutrons.
• Have the same atomic number but different mass numbers.

Ions

• Atoms or molecules that have gained or lost electrons, resulting in a net electric charge.
• Cations: Positively charged ions (lose electrons).
• Anions: Negatively charged ions (gain electrons).

Molecules

• Groups of two or more atoms held together by chemical bonds.
• Can be elements (e.g., O2) or compounds (e.g., H2O).

Chemical Bonds

• Forces that hold atoms together in molecules or compounds.
• Ionic Bonds: Formed through the transfer of electrons between atoms.
• Covalent Bonds: Formed through the sharing of electrons between atoms.
• Metallic Bonds: Found in metals, where electrons are delocalized.

Chemical Reactions

• Processes that involve the rearrangement of atoms and molecules to form new substances.
• Reactants: The starting materials in a chemical reaction.
• Products: The substances formed as a result of a chemical reaction.

Balancing Chemical Equations

• Ensuring that the number of atoms of each element is the same on both sides of the equation.

Stoichiometry

• The study of the quantitative relationships between reactants and products in chemical reactions.
• Mole: The amount of a substance that contains as many particles as there are atoms in 12 grams of carbon-12.

Acids

• Substances that donate protons (H+) or accept electrons.
• Have a pH less than 7.
• Taste sour.

Bases

• Substances that accept protons or donate electrons.
• Have a pH greater than 7.
• Taste bitter and feel slippery.

pH Scale

• A measure of the acidity or basicity of a solution.
• Ranges from 0 to 14.
• pH 7 is neutral.

Organic Chemistry

• The study of carbon-containing compounds.
• Carbon's ability to form stable bonds with itself and other elements allows for a vast array of organic compounds.

Functional Groups

• Specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.
• Alcohols (-OH), carboxylic acids (-COOH), amines (-NH2).

Polymers

• Large molecules made up of repeating subunits (monomers).
• Plastics, proteins, and DNA are examples of polymers.

Chemical Kinetics

• The study of reaction rates and the factors that affect them.
• Temperature, concentration, catalysts, and surface area.

Chemical Equilibrium

• The state in which the rate of the forward reaction equals the rate of the reverse reaction.
• Equilibrium constant (K) indicates the extent to which a reaction proceeds to completion.

Thermochemistry

• The study of the relationships between heat and chemical reactions.
• Exothermic reactions release heat.
• Endothermic reactions absorb heat.

Solutions

• Homogeneous mixtures in which one substance (solute) is dissolved in another (solvent).
• Concentration: The amount of solute dissolved in a given amount of solvent or solution.

Solubility

• The maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature.

Redox Reactions

• Reactions involving the transfer of electrons.
• Oxidation is the loss of electrons.
• Reduction is the gain of electrons.

Nuclear Chemistry

• The study of reactions involving the nuclei of atoms.
• Radioactivity: The emission of particles or energy from unstable nuclei.
• Nuclear fission: The splitting of a heavy nucleus into lighter nuclei.
• Nuclear fusion: The combining of light nuclei to form a heavier nucleus.