Some Basic Concepts of Chemistry - Vocabulary Flashcards

Flashcards covering the vocabulary and key concepts from Unit 1, 'Some Basic Concepts of Chemistry'.

Matter

Anything which has mass and occupies space.

Pure Substance

A substance in which all constituent particles are the same in chemical nature.

Homogeneous Mixture

A mixture in which the components completely mix with each other and have a uniform distribution throughout the bulk.

Heterogeneous Mixture

A mixture in which the composition is not uniform throughout and components are sometimes visible.

Element

A substance whose particles consist of only one type of atom.

Compound

A substance formed when two or more atoms of different elements combine together in a definite ratio.

Physical Properties

Properties that can be measured or observed without changing the identity or composition of the substance (e.g., color, odor, melting point).

Chemical Properties

Properties that require a chemical change to occur for measurement or observation (e.g., combustibility, reactivity with acids).

Density

The amount of mass per unit volume of a substance.

Scientific Notation

A method of expressing numbers as N × 10^n, where N is a number between 1.000… and 9.999…, and n is an exponent.

Significant Figures

Meaningful digits in a measurement, including all certain digits plus one estimated or uncertain digit.

Law of Conservation of Mass

Matter can neither be created nor destroyed in physical and chemical changes (Antoine Lavoisier, 1789).

Law of Definite Proportions

A given compound always contains exactly the same proportion of elements by weight (Joseph Proust).

Law of Multiple Proportions

If two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers (John Dalton, 1803).

Gay-Lussac's Law of Gaseous Volumes

When gases combine or are produced in a chemical reaction, they do so in a simple ratio by volume, provided all gases are at the same temperature and pressure (Gay-Lussac, 1808).

Avogadro's Law

Equal volumes of all gases at the same temperature and pressure should contain equal numbers of molecules (Avogadro, 1811).

Dalton's Atomic Theory

Matter consists of indivisible atoms; all atoms of a given element have identical properties; compounds are formed when atoms combine in a fixed ratio; chemical reactions involve reorganization of atoms.

Atomic Mass Unit (amu)

A mass exactly equal to one-twelfth of the mass of one carbon-12 atom.

Average Atomic Mass

The weighted average of the atomic masses of an element's naturally occurring isotopes.

Molecular Mass

The sum of the atomic masses of the elements present in a molecule.

Formula Mass

The sum of the atomic masses of the ions in a formula unit of an ionic compound.

Mole

The amount of a substance that contains as many particles or entities as there are atoms in exactly 12 g of the carbon-12 isotope (6.02214076 × 10^23).

Molar Mass

The mass of one mole of a substance in grams, numerically equal to the atomic/molecular/formula mass in u.

Percentage Composition

The mass per cent of each element present in a compound.

Empirical Formula

The simplest whole number ratio of various atoms present in a compound.

Molecular Formula

The exact number of different types of atoms present in a molecule of a compound.

Stoichiometry

The calculation of masses (sometimes volumes) of reactants and products involved in a chemical reaction.

Stoichiometric Coefficients

The numbers preceding the formulas in a balanced chemical equation, representing the number of molecules or moles.

Limiting Reagent

The reactant that is present in the least amount and gets consumed first, limiting the amount of product formed.

Molarity

The number of moles of the solute in 1 liter of the solution.

Molality

The number of moles of solute present in 1 kg of solvent.

Mole Fraction

The ratio of the number of moles of a particular component to the total number of moles in the solution.