Unit 1 Chem revision

C1: States of Matter

• Three states of matter: Solid (fixed shape and volume), liquid (fixed volume, takes shape of container), gas (no fixed shape or volume).

• Changes of state: Melting, freezing, boiling, condensation, sublimation, deposition.

• Kinetic Theory: Particles in solids vibrate, in liquids move randomly but stay close, in gases move freely and rapidly.

• Diffusion: Movement of particles from high to low concentration; faster in gases due to more kinetic energy.

• Brownian motion: Random movement of particles due to collisions with air or liquid molecules.

C2: Atoms, Elements, and Compounds

• Atoms: Smallest unit of matter, made of protons, neutrons, and electrons.

• Elements: Pure substances with only one type of atom.

• Compounds: Substances formed from two or more elements chemically bonded.

• Molecules: Two or more atoms chemically bonded, can be elements (O₂) or compounds (H₂O).

• Mixtures: Two or more substances physically combined, can be separated by physical means.

C2: Atoms, Elements, and Compounds (Continued)

• Atomic structure:

  • Proton: Charge +1, mass 1.

  • Neutron: Charge 0, mass 1.

  • Electron: Charge -1, negligible mass.

• Atomic number: Number of protons in an atom.

• Mass number: Number of protons + neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Electron shells: 2 in first shell, 8 in second, 8 in third (for first 20 elements).

C8: The Periodic Table

• Groups: Vertical columns; elements in the same group have similar properties.

• Periods: Horizontal rows; show increasing atomic number.

• Group 1 (Alkali Metals): Soft, low density, very reactive with water, reactivity increases down the group.

• Group 7 (Halogens): Non-metals, diatomic molecules, reactivity decreases down the group.

• Group 0 (Noble Gases): Unreactive due to full outer shell.

C8: The Periodic Table (Continued)

• Metals vs Non-metals:

  • Metals: Conduct electricity, malleable, ductile, high melting points.

  • Non-metals: Poor conductors, brittle, lower melting points.

• Transition Metals: Hard, dense, form colored compounds, act as catalysts.

• Trends in the periodic table:

  • Reactivity of metals increases down a group.

  • Reactivity of non-metals decreases down a group.

C9: Metals

• Metallic bonding: Positive ions in a ‘sea’ of delocalized electrons.

• Properties of metals: High melting/boiling points, good conductors, malleable.

• Reactivity series: K > Na > Ca > Mg > Al > Zn > Fe > Cu > Ag > Au.

• Reaction with water: More reactive metals react violently, less reactive metals don’t react.

• Reaction with acids: More reactive metals react vigorously, producing hydrogen gas.

• Rusting: Iron reacts with oxygen and water to form hydrated iron(III) oxide (rust).

C12: Experimental Techniques and Chemical Analysis

• Filtration: Separates insoluble solids from liquids.

• Crystallization: Separates a dissolved solid from a solution.

• Distillation: Separates liquids based on boiling points.

• Fractional distillation: Separates a mixture of liquids with close boiling points.

• Paper chromatography: Separates mixtures based on solubility; Rf value = distance traveled by substance ÷ distance traveled by solvent.

C12: Experimental Techniques and Chemical Analysis (Continued)

• Flame tests:

  • Lithium → Red

  • Sodium → Yellow

  • Potassium → Lilac

  • Calcium → Orange-red

  • Copper → Blue-green

• Tests for gases:

  • Hydrogen: Lit splint → squeaky pop.

  • Oxygen: Glowing splint → relights.

  • Carbon dioxide: Limewater → turns cloudy.

  • Chlorine: Damp litmus paper → bleaches white.

• Tests for ions:

  • Sodium hydroxide (NaOH) test for metal ions.

  • Silver nitrate (AgNO₃) test for halide ions.

  • Barium chloride (BaCl₂) test for sulfate ions.