Atomic Structure and Chemical Bonding

Atomic Structure

• Atoms are the fundamental building blocks of matter
• Atoms are composed of protons, neutrons, and electrons
• Protons have a positive charge, neutrons are neutral, and electrons have a negative charge
• Protons and neutrons reside in the atomic nucleus
• Electrons orbit the nucleus in specific energy levels or shells
• The number of protons in an atom determines its atomic number and identity
• The mass number is the sum of protons and neutrons in an atom
• Isotopes are atoms of the same element with different numbers of neutrons
• Atomic mass is the average mass of all isotopes of an element

Chemical Bonding

• Chemical bonds hold atoms together to form molecules and compounds
• Ionic bonds form when one atom transfers electrons to another
• Covalent bonds form when atoms share electrons
• Metallic bonds form in metals, where electrons are shared among all atoms
• Bond strength is influenced by electronegativity differences between atoms
• Polar covalent bonds occur when electrons are not shared equally
• Nonpolar covalent bonds occur when electrons are shared equally

Periodic Table

• The periodic table organizes elements by their atomic number and properties
• Elements in the same column (group) have similar chemical properties
• Elements in the same row (period) have increasing atomic number
• Metals are typically found on the left side of the periodic table
• Nonmetals are typically found on the right side of the table
• Metalloids have properties of both metals and nonmetals
• Elements are classified as alkali metals, alkaline earth metals, transition metals, halogens, and noble gases

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms
• Reactants are substances consumed in a reaction
• Products are substances formed in a reaction
• Chemical equations represent reactions using symbols and formulas
• Balanced equations maintain the same number of atoms of each element on both sides of the equation
• Reactions can be categorized based on various factors, such as the type of reaction, reactants involved, energy changes, and state changes
• Examples of common reaction types include synthesis, decomposition, single replacement, double replacement, combustion, and acid-base reactions

States of Matter

• Matter exists in solid, liquid, and gaseous states
• Solids have a definite shape and volume
• Liquids have a definite volume but take the shape of their container
• Gases have neither a definite shape nor a definite volume
• The state of matter depends on the temperature and pressure

Stoichiometry

• Stoichiometry is the calculation of quantities in chemical reactions
• Mole ratios are used to relate amounts of reactants and products
• Molar mass is the mass of one mole of a substance
• Calculations involve converting between grams, moles, and number of particles
• Limiting reactant is the reactant that is used up first in a reaction

Solutions

• Solutions are homogeneous mixtures of two or more substances
• Solutes dissolve in solvents
• Concentration is a measure of the amount of solute in a given amount of solution
• Solutions can be described using various concentration units, such as molarity

Acids and Bases

• Acids are substances that donate protons (H+)
• Bases are substances that accept protons (H+)
• The pH scale measures the acidity or basicity of a solution
• Strong acids and bases completely ionize in water
• Weak acids and bases partially ionize

Thermodynamics

• Thermodynamics studies energy changes in chemical processes
• Exothermic reactions release heat
• Endothermic reactions absorb heat
• Enthalpy (H) is a measure of heat content
• Entropy (S) is a measure of disorder
• Gibbs free energy (G) determines whether a reaction is spontaneous under certain conditions

Organic Chemistry

• Organic chemistry is the study of carbon-containing compounds
• Carbon has unique bonding properties and can form chains and rings
• Hydrocarbons are organic compounds containing only carbon and hydrogen
• Functional groups dictate the properties of organic compounds.
• Examples of functional groups include alkanes, alkenes, alkynes, alcohols, ketones, and aldehydes.