Title: Chemistry Fundamentals — LearnCoachAssist

Q: What is chemistry?
A: Chemistry is the scientific study of matter, its properties, composition, structure, and the changes it undergoes during chemical reactions.

Q: What is matter?
A: Matter is anything that has mass and occupies space. It exists in three primary states: solid, liquid, and gas.

Q: What are the three main states of matter?
A: The three main states of matter are solid (definite shape and volume), liquid (definite volume but indefinite shape), and gas (neither definite shape nor volume).

Q: What is an element?
A: An element is a pure substance that cannot be broken down into simpler substances by chemical means and is made of only one type of atom.

Q: What is a compound?
A: A compound is a pure substance composed of two or more different elements chemically bonded in fixed proportions.

Q: What is a mixture?
A: A mixture is a combination of two or more substances that are not chemically combined and retain their individual properties. Mixtures can be homogeneous (uniform) or heterogeneous (non-uniform).

Q: What is an atom?
A: An atom is the smallest unit of an element that retains the chemical properties of that element, consisting of a nucleus and electrons.

Q: What are the three main subatomic particles?
A: The three main subatomic particles are protons (positive charge in nucleus), neutrons (no charge in nucleus), and electrons (negative charge orbiting nucleus).

Q: What is the atomic number?
A: The atomic number is the number of protons in an atom's nucleus, which defines the element and its position in the periodic table.

Q: What is the mass number?
A: The mass number is the total number of protons and neutrons in an atom's nucleus.

Q: What is an isotope?
A: Isotopes are atoms of the same element with the same atomic number but different mass numbers due to varying numbers of neutrons.

Q: What is the periodic table?
A: The periodic table is a tabular arrangement of chemical elements organized by increasing atomic number, showing periodic trends in properties.

Q: Who is credited with creating the modern periodic table?
A: Dmitri Mendeleev is credited with creating the modern periodic table in 1869, arranging elements by atomic mass and predicting undiscovered elements.

Q: What are periods and groups in the periodic table?
A: Periods are horizontal rows indicating energy levels; groups (or families) are vertical columns with similar chemical properties due to valence electrons.

Q: What are metals, nonmetals, and metalloids?
A: Metals are shiny, conductive, malleable elements on the left; nonmetals are dull, brittle, poor conductors on the right; metalloids have properties of both along the staircase line.

Q: What is ionic bonding?
A: Ionic bonding occurs when electrons transfer from a metal to a nonmetal, forming oppositely charged ions that attract each other electrostatically.

Q: What is covalent bonding?
A: Covalent bonding involves sharing of electrons between nonmetal atoms to achieve stable electron configurations.

Q: What is a molecule?
A: A molecule is a group of two or more atoms held together by covalent bonds, representing the smallest unit of a compound.

Q: What are valence electrons?
A: Valence electrons are the electrons in the outermost shell of an atom, determining its chemical reactivity and bonding behavior.

Q: What is a Lewis dot structure?
A: A Lewis dot structure uses dots to represent valence electrons around atomic symbols, showing bonding and lone pairs in molecules.

Q: What is a chemical reaction?
A: A chemical reaction is a process where reactants transform into products by breaking and forming chemical bonds.

Q: What are reactants and products?
A: Reactants are starting substances in a chemical reaction; products are the substances formed after the reaction.

Q: What does a balanced chemical equation represent?
A: A balanced chemical equation shows the same number of each type of atom on both reactant and product sides, obeying the law of conservation of mass.

Q: What are the five main types of chemical reactions?
A: The five main types are synthesis (A + B → AB), decomposition (AB → A + B), single replacement (A + BC → AC + B), double replacement (AB + CD → AD + CB), and combustion (fuel + O₂ → CO₂ + H₂O).

Q: What is the law of conservation of mass?
A: The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction; total mass remains constant.

Q: What is the kinetic molecular theory?
A: The kinetic molecular theory explains gas behavior: particles are in constant motion, have negligible volume, elastic collisions, and kinetic energy proportional to temperature.

Q: What is the melting point?
A: The melting point is the temperature at which a solid turns into a liquid at standard pressure.

Q: What is the boiling point?
A: The boiling point is the temperature at which a liquid's vapor pressure equals atmospheric pressure, turning it into gas.

Q: What is vapor pressure?
A: Vapor pressure is the pressure exerted by gas molecules in equilibrium with their liquid phase at a given temperature.

Q: What are intermolecular forces?
A: Intermolecular forces are attractions between molecules, including hydrogen bonding, dipole-dipole, and London dispersion forces, affecting boiling/melting points.

Q: What is a solution?
A: A solution is a homogeneous mixture of two or more substances, with a solute dissolved in a solvent.

Q: What are solute and solvent?
A: The solute is the substance dissolved (usually smaller amount); the solvent is the dissolving medium (usually larger amount).

Q: What is molarity?
A: Molarity (M) is the concentration unit defined as moles of solute per liter of solution: M = mol/L.

Q: What factors affect solubility?
A: Solubility is affected by temperature (increases for solids, varies for gases), pressure (Henry's law for gases), and nature of solute/solvent ('like dissolves like').

Q: What is Henry's law?
A: Henry's law states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid.

Q: What is an acid according to the Arrhenius definition?
A: An Arrhenius acid increases H⁺ (H₃O⁺) concentration in water, e.g., HCl → H⁺ + Cl⁻.

Q: What is a base according to the Arrhenius definition?
A: An Arrhenius base increases OH⁻ concentration in water, e.g., NaOH → Na⁺ + OH⁻.

Q: What is the pH scale?
A: The pH scale measures acidity/basicity from 0 to 14; pH < 7 is acidic, pH = 7 neutral, pH > 7 basic. pH = -log[H⁺].

Q: What is a neutralization reaction?
A: Neutralization is the reaction between an acid and base producing salt and water, e.g., HCl + NaOH → NaCl + H₂O.

Q: What is a buffer solution?
A: A buffer resists pH changes when small amounts of acid or base are added, typically a weak acid and its conjugate base.

Q: What is a mole in chemistry?
A: A mole is the amount of substance containing Avogadro's number (6.022 × 10²³) of particles, like atoms or molecules.

Q: What is Avogadro's number?
A: Avogadro's number (6.022 × 10²³) is the number of particles in one mole of any substance.

Q: How is molar mass calculated?
A: Molar mass is the mass of one mole of a substance in grams, calculated by summing atomic masses of elements in the formula.

Q: What is stoichiometry?
A: Stoichiometry is the quantitative relationship between reactants and products in a balanced chemical equation, used for mole-mole conversions.

Q: What is a limiting reactant?
A: The limiting reactant is the reactant that is completely consumed first, determining the maximum product yield.

Q: What is enthalpy (H)?
A: Enthalpy is the total heat content of a system at constant pressure; change in enthalpy (ΔH) measures heat absorbed or released in reactions.

Q: What is an exothermic reaction?
A: An exothermic reaction releases heat to surroundings (ΔH < 0), like combustion.

Q: What is an endothermic reaction?
A: An endothermic reaction absorbs heat from surroundings (ΔH > 0), like photosynthesis.

Q: What is activation energy?
A: Activation energy is the minimum energy required for reactants to form products, often shown as the peak in an energy diagram.

Q: What factors affect reaction rate?
A: Reaction rate is affected by concentration, temperature, surface area, catalysts, and nature of reactants.