Unit 1 – Some Basic Concepts of Chemistry (Vocabulary Review)

A comprehensive set of vocabulary flashcards covering fundamental terms, laws, units, and concepts presented in Unit 1: Some Basic Concepts of Chemistry. These cards will help reinforce key terminology required for mastering introductory chemical principles.

Chemistry

The branch of science that studies the preparation, properties, structure, and reactions of material substances.

Alchemy

A historical practice, precursor to modern chemistry, focused on goals such as converting base metals into gold and discovering the elixir of life.

Iatrochemistry

A medieval branch of chemistry that applied chemical principles to medicine and pharmaceuticals.

Philosopher’s Stone

A legendary substance in alchemy believed capable of converting base metals like iron and copper into gold.

Elixir of Life

A mythical alchemical potion thought to grant immortality.

Rasayan Shastra

Ancient Indian term for chemistry, encompassing metallurgy, medicine, glass, dyes, and other chemical arts.

State of Matter – Solid

Physical state with definite shape and volume; particles are closely packed and fixed in position.

State of Matter – Liquid

Physical state with definite volume but no fixed shape; particles are close but can move past one another.

State of Matter – Gas

Physical state lacking both definite shape and volume; particles are far apart and move freely.

Element

A pure substance consisting of only one type of atom that cannot be broken down by chemical means.

Compound

A pure substance composed of two or more elements chemically combined in a fixed ratio.

Mixture

A physical combination of two or more substances whose composition can vary and whose components retain their identity.

Homogeneous Mixture

A mixture with uniform composition throughout; components are not visibly distinguishable (e.g., salt solution).

Heterogeneous Mixture

A mixture with non-uniform composition; different components are visibly distinct (e.g., sand and iron filings).

Physical Property

A characteristic that can be observed or measured without changing the substance’s composition (e.g., colour, melting point).

Chemical Property

A characteristic that describes a substance’s ability to undergo chemical change (e.g., combustibility, acidity).

SI (International System) Unit

The globally accepted set of base and derived units for scientific measurement.

Atomic Mass Unit (u)

A mass equal to one-twelfth the mass of a carbon-12 atom; used to express atomic and molecular masses.

Average Atomic Mass

The weighted mean of the masses of an element’s naturally occurring isotopes.

Molecular Mass

The sum of atomic masses of all atoms in a molecule.

Formula Mass

The sum of atomic masses of ions in an ionic compound’s empirical formula (used when discrete molecules are absent).

Molar Mass

The mass of one mole of a substance, numerically equal to its atomic or molecular mass expressed in grams per mole (g mol⁻¹).

Mole

The SI unit for amount of substance; contains exactly 6.022 140 76 × 10²³ entities (Avogadro constant).

Avogadro Constant (Nₐ)

6.022 × 10²³, the number of specified elementary entities in one mole of substance.

Law of Conservation of Mass

In a chemical or physical change, matter is neither created nor destroyed; total mass remains constant.

Law of Definite Proportions

A given compound always contains the same elements in the same fixed mass ratio, regardless of its source.

Law of Multiple Proportions

When two elements form more than one compound, the masses of one element combining with a fixed mass of the other are in simple whole-number ratios.

Gay-Lussac’s Law of Gaseous Volumes

At constant temperature and pressure, the volumes of gaseous reactants and products are in simple whole-number ratios.

Avogadro’s Law

Equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules.

Dalton’s Atomic Theory

Early theory stating that matter consists of indivisible atoms, atoms of each element are identical, and chemical reactions reorganize atoms without creating or destroying them.

Stoichiometry

The quantitative study of reactants and products in a chemical reaction based on a balanced equation.

Limiting Reagent

The reactant that is completely consumed first, thus limiting the amount of product formed in a reaction.

Molarity (M)

Concentration unit representing moles of solute per litre of solution.

Molality (m)

Concentration unit representing moles of solute per kilogram of solvent.

Mole Fraction (χ)

Ratio of moles of a component to the total moles of all components in a mixture or solution.

Mass Percent (w/w %)

Concentration unit expressing mass of solute per 100 units of total mass of solution.

Scientific Notation

Method of expressing numbers as N × 10ⁿ, where 1 ≤ N < 10 and n is an integer, for handling very large or small values.

Significant Figures

Digits in a measured number that include all certain digits plus the first uncertain digit, reflecting measurement precision.

Dimensional Analysis

Problem-solving technique that uses unit factors to convert one set of units to another.

Density

Mass per unit volume of a substance, commonly expressed in g cm⁻³ or kg m⁻³.

Analytical Balance

A high-precision laboratory instrument used to measure mass accurately, often to four decimal places.

Volumetric Flask

Calibrated laboratory glassware used to prepare solutions of precise volume and known concentration.

Prefix – kilo (k)

SI prefix denoting 10³ (one thousand) times the base unit.

Prefix – milli (m)

SI prefix denoting 10⁻³ (one thousandth) of the base unit.

Kelvin (K)

The SI base unit of thermodynamic temperature, with absolute zero at 0 K.