Chemistry Definitions Quiz

Study Notes

Law of Conservation of Mass: Matter remains unchanged; it cannot be created or destroyed.
Law of Constant Composition: A compound's element composition is uniform across all samples.
Law of Combining Gas Volumes: Gas volumes reacting or produced in a reaction are in simple numerical ratios, provided pressure and temperature are constant.
Avogadro’s Hypothesis: Identical gas volumes at the same pressure and temperature contain an equal number of molecules.
Valence: Indicates the number of electrons an element can lose, gain, or share in reactions.
Atomic Mass Unit (amu): Defined by the mass of the C-12 isotope (12.0000); 1 amu is 1/12 of this mass.
Equivalent Mass: Mass of an element that combines with or displaces eight mass parts of oxygen.
Empirical Formula: Shows the simplest whole-number ratio of atoms in a compound.
Molecular Formula: Represents the actual number of atoms in a molecule.
Temperature Units: Measured in degrees Celsius (C˚), Kelvin (K), and Fahrenheit (F˚), indicating heat flow direction.
Avogadro's Number: 6.023 × 10²³, representing the number of atoms in 1 mole or the number of molecules in 1 mole of a compound.
Molar Mass: Mass of one mole of atoms or molecules expressed in grams.

Law of Mass Conservation: Mass of reactants equals the mass of products in a reaction.
Law of Constant Composition: Element ratios remain constant across compound samples.
Atomic Mass: Relates to Avogadro's number (6.023 × 10²³) for calculating absolute mass.
Equivalent Mass Relationship: Compares equivalent masses based on the same compound interactions.
Atomic Mass, Equivalent Mass, and Valence: Atomic mass of an element equals its equivalent mass divided by the valence.
Gas Density: Density (ρ in g/cm³) calculated as mass (g) divided by volume (cm³).
Mole Concept:
- Number of moles (n in mol) equals mass (g) divided by molar mass (g/mol).
- Number of moles also relates to Avogadro's number.
Mass Percentage:
- Calculated as (Mass of Element / Mass of Compound) × 100%.
Mass of Element in a Compound: Determined by the ratio of the element's mass to the compound's total mass.
Empirical Formula Ratio: Based on the mass or percentage of the element within the compound, establishing a foundational understanding of chemical formulas.