Grade 11 Chemistry – Core Vocabulary

A collection of 200 English vocabulary flashcards summarizing key Grade 11 Chemistry concepts, terms, and definitions from the lecture transcript.

Qualitative Observation

A description made with the senses, such as colour, lustre, or texture, that involves no measurement.

Quantitative Observation

A description that includes numerical measurement, such as mass, volume, or temperature.

Lustre

The way a surface reflects light; the shininess of a substance.

Particle Theory of Matter

Model stating all matter is made of tiny particles that are in constant motion and attract one another.

Postulate

A fundamental statement accepted as true within a theory; one of the five ideas in particle theory.

Atom

The smallest unit of an element that retains the element’s properties.

Molecule

A particle made of two or more atoms covalently bonded together.

Ion

An atom or molecule with an electric charge due to loss or gain of electrons.

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Proton

Positively charged sub-atomic particle located in the nucleus; mass ≈1 u.

Neutron

Neutral sub-atomic particle in the nucleus with a mass ≈1 u.

Electron

Negatively charged sub-atomic particle occupying energy levels outside the nucleus.

Atomic Number

The number of protons in an atom; defines the element.

Mass Number

The total number of protons and neutrons in an atom’s nucleus.

Isotope

Atoms of the same element with different numbers of neutrons and different masses.

Radioisotope

An unstable isotope that decays spontaneously, emitting radiation.

Atomic Nucleus

Dense central core of an atom containing protons and neutrons.

Energy Level

Fixed region around a nucleus where electrons of similar energy are likely to be found.

Valence Electron

Electron in the outermost energy level; involved in chemical reactions.

Core Electron

Electron in an inner energy level that is not involved in bonding.

Bohr–Rutherford Diagram

Atomic diagram showing nucleus and electrons arranged in concentric energy levels.

Period

Horizontal row in the periodic table; indicates number of occupied energy levels.

Group

Vertical column in the periodic table whose elements share similar properties.

Lanthanoids

Series of 14 elements following lanthanum, often shown below the main table.

Actinoids

Series of 14 elements following actinium; many are radioactive.

Metal

Element that is typically shiny, malleable, and conducts heat and electricity well.

Non-metal

Element that is dull, brittle in solid form, and a poor conductor of heat and electricity.

Metalloid

Element with properties intermediate between metals and non-metals.

Alkali Metals

Highly reactive group-1 metals such as Li, Na, and K.

Alkaline Earth Metals

Reactive group-2 metals such as Mg and Ca.

Halogens

Group-17 non-metals known for high reactivity, e.g., F, Cl, Br.

Noble Gases

Group-18 gases with full valence shells; very unreactive.

Atomic Radius

Distance from nucleus to outermost electron; size of an atom.

Electronegativity

The displacement of shared valence electrons in a chemical bond. 

Ionization Energy

Energy required to remove one electron from a gaseous atom.

Shielding Electrons

Inner electrons that block nuclear attraction for valence electrons.

Effective Nuclear Charge

Net positive charge experienced by valence electrons (Z – shielding).

Stable Octet

Electron configuration with eight valence electrons, associated with stability.

Lewis Electron Dot Diagram

Symbolic diagram showing an element’s valence electrons as dots around its symbol.

Ionic Bond

Electrostatic attraction between oppositely charged ions formed by electron transfer.

Covalent Bond

Shared pair of electrons between two non-metal atoms.

Non-polar Covalent Bond

Covalent bond with equal sharing of electrons (ΔEN ≤0.5).

Polar Covalent Bond

Covalent bond with unequal sharing of electrons (ΔEN 0.6–1.7).

Electronegativity Difference

Numerical difference in electronegativity used to predict bond type.

Law of Definite Proportions

Statement that a compound always contains the same elements in the same ratio.

Binary Ionic Compound

Ionic compound containing only two element types: a metal and a non-metal.

Multivalent Metal

Metal capable of forming ions with more than one possible charge.

Stock Naming System

Use of Roman numerals in a compound’s name to show a metal’s charge.

Polyatomic Ion

Charged group of covalently bonded atoms acting as a single ion.

Hydroxide Ion

OH⁻ polyatomic ion common in bases.

Nitrate Ion

NO₃⁻ polyatomic ion found in many fertilizers.

Hydrogen Carbonate Ion

HCO₃⁻ ion, also called bicarbonate, important in buffering systems.

Carbonate Ion

CO₃²⁻ polyatomic ion present in limestone and shells.

Sulphate Ion

SO₄²⁻ polyatomic ion common in industrial chemicals.

Phosphate Ion

PO₄³⁻ polyatomic ion vital to DNA and fertilizers.

Ammonium Ion

NH₄⁺ polyatomic cation derived from ammonia.

Binary Covalent Compound

Compound of two non-metals named with Greek prefixes.

Prefix Mono-

Indicates one atom of an element in covalent naming.

Prefix Di-

Indicates two atoms in covalent naming.

Prefix Tri-

Indicates three atoms in covalent naming.

Prefix Tetra-

Indicates four atoms in covalent naming.

Prefix Penta-

Indicates five atoms in covalent naming.

Prefix Hexa-

Indicates six atoms in covalent naming.

Prefix Hepta-

Indicates seven atoms in covalent naming.

Prefix Octa-

Indicates eight atoms in covalent naming.

Prefix Nona-

Indicates nine atoms in covalent naming.

Prefix Deca-

Indicates ten atoms in covalent naming.

Melting Point

Temperature at which a solid becomes a liquid.

Boiling Point

Temperature at which a liquid becomes a gas throughout the bulk.

Solubility

Amount of solute that dissolves in a solvent at a given temperature.

Kinetic Molecular Theory

Model describing particles in constant motion whose energy depends on temperature.

London Dispersion Force

Weak intermolecular force caused by temporary dipoles in all molecules.

Dipole-Dipole Force

Attraction between permanent partial charges of polar molecules.

Hydrogen Bond

Strong dipole attraction involving H bonded to F, O, or N.

Polar Molecule

Molecule with an uneven distribution of charge due to polar bonds and asymmetry.

Non-polar Molecule

Molecule whose electrons are evenly distributed, lacking overall dipole.

Mole

SI amount of substance containing 6.02 × 10²³ entities.

Avogadro’s Number

6.02 × 10²³, the number of particles in one mole.

Molar Mass

Mass of one mole of a substance expressed in grams per mole.

Scientific Notation

Method of writing very large or small numbers as a power of ten.

Significant Figures

Digits in a measurement that convey its precision.

Law of Conservation of Mass

Mass is neither created nor destroyed in a chemical reaction.

Word Equation

Chemical equation written using names of reactants and products.

Skeleton Equation

Unbalanced chemical equation showing formulas but no coefficients.

Balanced Chemical Equation

Equation with equal numbers of each atom on both sides, satisfying mass conservation.

Mole Ratio

Proportion of moles of reactants and products in a balanced equation.

Synthesis Reaction

Reaction where two or more substances combine to form one product (A+B→AB).

Decomposition Reaction

Reaction where a single compound breaks down into simpler substances (AB→A+B).

Single Displacement Reaction

Reaction where one element replaces another in a compound (A+BC→AC+B).

Double Displacement Reaction

Reaction involving exchange of ions between two compounds (AB+CD→AD+CB).

Activity Series of Metals

List ranking metals by their ability to displace other metals or H⁺.

Activity Series of Halogens

Order of halogen reactivity: F>Cl>Br>I>At.

Corrosion

Slow chemical reaction of a metal with oxygen producing an oxide.

Rust

Hydrated iron(III) oxide formed when iron corrodes.

Smelting

Extraction of metals from ores using single-displacement reactions at high temperature.

Ore

Naturally occurring rock containing valuable metal compounds.

Alloy

Mixture of two or more metals, or a metal and another element.

Electrolysis

Use of electricity to drive a non-spontaneous chemical reaction.

Acid

Substance that produces H⁺ (or H₃O⁺) ions in water; pH <7.