Chemistry: Atomic Structure & Bonding

Atomic Structure

• Atoms: Basic units of matter, consisting of protons, neutrons, and electrons.
• Protons: Positively charged particles located in the nucleus; determines the element's identity.
• Neutrons: Neutral particles in the nucleus; contribute to atomic mass but not charge.
• Electrons: Negatively charged particles that orbit the nucleus; involved in chemical bonding.
• Atomic Number: Number of protons in an atom; unique to each element.
• Mass Number: Sum of protons and neutrons in the nucleus; indicates the total mass of an atom.

Chemical Bonding

• Ionic Bonds: Formed when electrons are transferred from one atom to another, resulting in charged ions.
• Covalent Bonds: Formed when two atoms share electrons; common in organic molecules.
• Metallic Bonds: Involve a 'sea of electrons' around positively charged metal ions, contributing to electrical conductivity.
• Polar and Nonpolar Molecules: Polar molecules have an unequal distribution of charge, while nonpolar molecules have symmetrical charge distribution.

States of Matter

• Solid: Definite shape and volume; particles are closely packed and vibrate in fixed positions.
• 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.
• Phase Changes: Transitions between states of matter (e.g., melting, boiling, condensation).
• Temperature and Pressure: Affect the state of matter; higher temperature or lower pressure can change solids to liquids or gases.

Periodic Table

• Elements: Arranged by increasing atomic number; grouped by similar chemical properties.
• Groups: Vertical columns; elements in the same group have similar valence electron configurations (e.g., Group 1: Alkali metals).
• Periods: Horizontal rows; indicate the number of electron shells.
• Metals, Nonmetals, and Metalloids: Categories based on elemental properties; metals are conductive and malleable, while nonmetals are poor conductors.

Stoichiometry

• Mole Concept: A mole represents 6.022 x 10²³ particles of a substance; used for converting between mass and number of particles.
• Balancing Equations: Conservation of mass requires that the number of atoms of each element is the same on both sides of a chemical equation.
• Molar Ratios: Derived from balanced equations; used to calculate reactants and products in chemical reactions.
• Calculating Yield: Theoretical yield vs. actual yield; percentage yield = (actual yield/theoretical yield) x 100%.

Atomic Structure

• Atoms are the building blocks of matter, composed of three subatomic particles: protons, neutrons, and electrons.
• Protons are positively charged particles found in the atom's nucleus. The number of protons, known as the atomic number, defines the element.
• Neutrons are neutral particles also located in the nucleus. They contribute to the atom's mass but not its charge.
• Electrons are negatively charged particles that orbit the nucleus in shells. They are responsible for chemical bonding.
• The mass number represents the total number of protons and neutrons in an atom, indicating its atomic mass.

Chemical Bonding

• Ionic bonds form when electrons are transferred between atoms, creating positively and negatively charged ions (cations and anions) that attract each other.
• Covalent bonds occur when atoms share electrons to attain a stable electron configuration, resulting in molecules.
• Metallic bonds involve a "sea" of delocalized electrons shared amongst positively charged metal ions, explaining their conductivity.
• Polar molecules possess an uneven distribution of charge due to differing electronegativity, resulting in a dipole moment. Nonpolar molecules have a uniform distribution of charge.

States of Matter

• Solids have a fixed shape and volume due to tightly packed particles that only vibrate.
• Liquids maintain a constant volume but take the shape of their container, allowing particles to move past each other.
• Gases have no fixed shape or volume, with particles widely spaced and moving freely.
• Phase changes are transitions between states of matter, such as melting (solid to liquid), boiling (liquid to gas), and condensation (gas to liquid).
• Temperature and pressure influence the state of matter. Increased temperature can change solids to liquids or liquids to gases, while reduced pressure can cause liquids to vaporize.

Periodic Table

• The periodic table organizes elements by increasing atomic number and groups them by similar chemical properties.
• Groups (vertical columns) contain elements with similar valence electron configurations, leading to shared chemical behaviors.
• Periods (horizontal rows) represent the number of electron shells an atom possesses.
• Metals, nonmetals, and metalloids are categories based on physical and chemical properties, with metals typically being conductive and malleable, while nonmetals are poor conductors.

Stoichiometry

• The mole is a unit used to measure the amount of substance, representing 6.022 x 10²³ particles (Avogadro's number).
• Balancing chemical equations ensures that the number of atoms of each element is equal on both sides, upholding the law of conservation of mass.
• Molar ratios, derived from balanced equations, relate the number of moles of reactants and products in a chemical reaction.
• Calculating yield involves determining the theoretical and actual amounts of product. The percentage yield is calculated by dividing the actual yield by the theoretical yield and multiplying by 100%.

This quiz tests your knowledge of atomic structure and chemical bonding. It covers key concepts such as protons, neutrons, electrons, and the different types of chemical bonds, including ionic, covalent, and metallic bonds. Assess your understanding of these fundamental topics in chemistry.