Chemistry is the study of matter and its changes over time.
Based on 118 chemical elements, which consist of atoms.
Key Concepts
Matter: Anything that has mass and takes up space.
Elements: Pure substances with indistinguishable atoms.
Compounds: Pure substances with two or more elements in definite proportions (e.g., water).
Mixtures: Non-chemical combinations of substances (solid, liquid, or gas).
Solutions: Homogeneous mixtures with a single phase.
States of Matter
Gas: No fixed volume or shape.
Liquid: Distinct volume, no specific shape.
Solid: Distinct volume and shape.
Plasma: Ionized gas with no fixed volume or shape.
Properties of Matter
Physical: State, size, shape, color.
Measurable: Mass, volume, ductility, malleability, lustre, hardness, boiling point, melting point, solubility, thermal & electrical conductivity.
Separation of Mixtures
Important for mining, petrochemicals, materials production and pharmaceuticals.
Atomic Theory
Proposed by Dalton:
Matter consists of tiny particles called atoms.
Atoms are indestructible and rearrange in chemical reactions.
Atoms of an element are identical in mass and properties.
Atoms of different elements have different masses and properties.
Compounds have atoms in fixed numerical ratios.
Laws
Law of Conservation of Mass: Mass is conserved during a chemical reaction.
Law of Definite Proportions: Elements combine in the same proportions by mass in a compound.
Law of Multiple Proportions: If two elements form more than one compound, the masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.
Chemical Equations
Representation of chemical reactions using symbols and formulas.
Must be balanced to conserve atoms.
Atomic Structure
Atoms are divisible and composed of subatomic particles.
Subatomic Particles
Electron: negative charge, small mass.
Proton: positive charge, found in nucleus.
Neutron: no charge, found in nucleus.
Atomic Number and Mass Number
Atomic Number (Z): Number of protons.
Mass Number (A): Number of protons plus neutrons.
Isotopes
Atoms of an element with different numbers of neutrons.
Atomic Mass and Weight
Atomic mass is measured in atomic mass units (u).
Atomic weight is the average of isotopic masses, weighted by natural abundance.
Periodic Table
Elements ordered by increasing atomic number.
Groups (columns): elements with similar properties.
Periods (rows): arranged in order of increasing atomic number.
Element Types
Metals, nonmetals, and metalloids.
Blocks on Periodic Table
s-block, p-block, d-block, f-block (lanthanides and actinides).