Atomic Structure and Periodic Table

Atomic Structure

• Atoms are the fundamental building blocks of matter.
• Atoms consist of a nucleus containing protons and neutrons, surrounded by orbiting electrons.
• Protons have a positive charge, electrons have a negative charge, and neutrons have no charge.
• The number of protons in an atom's nucleus defines its atomic number, which determines the element.
• The mass number of an atom is the sum of protons and neutrons.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Atomic orbitals describe regions of space where electrons are likely to be found.

Periodic Table

• The periodic table organizes elements based on their atomic structure and properties.
• Elements are arranged by increasing atomic number.
• Elements with similar properties are grouped in vertical columns called groups or families.
• Elements are also arranged in horizontal rows called periods.
• Elements in the same group have similar valence electron configurations, leading to similar chemical properties.
• Metals typically have high thermal and electrical conductivity, are lustrous, and are malleable.
• Nonmetals typically are poor conductors of heat and electricity and are often brittle.
• Metalloids exhibit properties of both metals and nonmetals.

Chemical Bonding

• Chemical bonds are forces that hold atoms together in molecules or compounds.
• Ionic bonds form between a metal and a nonmetal when one atom transfers electrons to another.
• Covalent bonds form between nonmetals when atoms share electrons.
• Metallic bonds occur between metal atoms, where electrons are delocalized (shared among many atoms).
• The strength of bonds affects the properties of substances.

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms to form new substances.
• Chemical reactions are represented by chemical equations.
• Reactants are the substances that undergo change, and products are the new substances formed.
• The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction.
• Chemical reactions can be classified into different types, such as synthesis, decomposition, single displacement, double displacement, and combustion.
• Factors affecting reaction rate include temperature, concentration of reactants, surface area, and presence of catalysts.

States of Matter

• Matter exists in three primary states: solid, liquid, and gas.
• Solids have a fixed shape and volume, liquids have a fixed volume but take the shape of their container, and gases have neither a fixed shape nor volume.
• Changes of state involve energy transfer.
• Phase changes include melting, freezing, evaporation, condensation, sublimation, and deposition.

Solutions

• Solutions are homogeneous mixtures of two or more substances.
• The solvent is the dissolving medium, and the solute is the substance being dissolved.
• Solubility describes the ability of a substance to dissolve in a given solvent.
• Factors affecting solubility include temperature, pressure, and nature of solute and solvent.
• Solutions can be categorized as saturated, unsaturated, or supersaturated based on the amount of solute dissolved.

Acids and Bases

• Acids are substances that release hydrogen ions (H+) when dissolved in water.
• Bases are substances that release hydroxide ions (OH-) when dissolved in water.
• The pH scale measures the acidity or basicity of a solution.
• Acids and bases react with each other in neutralization reactions to form water and a salt.
• Indicators are substances that change color in the presence of acids or bases.

Stoichiometry

• Stoichiometry involves calculating the quantities of reactants and products in chemical reactions.
• Balanced chemical equations are used to determine mole ratios.
• Mole ratios are used to convert between moles of reactants and products.
• Stoichiometry calculations are essential for quantitative analysis in chemical reactions.

Thermodynamics

• Thermodynamics is the study of energy and its transformations.
• The first law of thermodynamics describes the conservation of energy.
• The second law of thermodynamics describes the tendency of systems to become more disordered (entropy).
• The third law of thermodynamics describes the behavior of systems at absolute zero.