Chemistry Solutions and Matter Classification

Homogenous (solution)

• Uniform composition
• Solute dissolves in solvent
• Solvents can be solid, liquid, or gas
• Examples: sugar water, salt water, gasoline

Solution Types

• Saturated: Correct amount of solute in solvent
• Unsaturated: Very few solute in solvent
• Supersaturated: Too much solute in solvent

Classification of Matter

• Systematic way of determining classification using properties of matter
• Change Involved During Measurement
  • Physical Change
    • Characteristic that can be observed without changing composition.
    • Involves physical change like shape, size, and state.
    • Qualitative: Color, odor.
    • Quantitative: Mass, Volume, Density, Temperature
  • Chemical Change
    • Composed of 2 or more elements chemically combined in definite proportions.
    • Examples: Water, sugar, salt
    • Acids: Less than pH 7
    • Bases: Greater than pH 7
    • Salts: Combination of Acids and Bases
    • Compounds: Often have to be different elements. Diatomic does not equal a compound.
• Amount of Matter During Measurement
  • Intensive property: Characteristic that does not change value when the amount of substance is changed.
    • Examples: Color, Density, Boiling point, Melting point
  • Extensive Property: Characteristic that changes value as the amount of substance is changed
    • Examples: Volume, Mass, Weight, Length

Mixtures

• Combination of two or more (pure) elements/compounds

Development of Atomic Theory

• Law of Conservation of Mass: Mass cannot be created nor destroyed (Antoine Lavoisier, 1789)
• Law of Definite Composition: Compounds contain the same elements in exactly the same proportion by mass (Joseph Proust, 1799)
• Dalton’s Atomic Theory: Matter is composed of atoms, and elements are composed of identical atoms (John Dalton, 1808)
  • Matter is composed of small, indivisible particles called atoms.
  • All atoms of a given element are identical both in mass and in chemical properties.
  • Atoms of different elements have different masses and different chemical properties.

Atom and its Properties

• "Atomos" = “indivisible”
• The smallest unit of an element that retains all chemical properties of an element.
• Leucippus and Democritus agreed that they are composed of small, finite particles.
• Aristotle’s idea that they were made up of elements stayed for up to 2000 years.
• Molecules:
  • Criteria:
    • Does not spontaneously separate or settle out over time.
    • Tyndall effect can be observed by eye (nanometer-sized particles)
    • Tyndall effect: Particles of solute and solvent are smaller than the wavelength of the visible light.
• Law of definite proportions: Given chemical compound always contains its component elements in a fixed ratio regardless the substance’s mass.

Subatomic Particles

• Michael Faraday (1834): Electricity consists of particles.
• George J.Stoney (1874): Electrons (unit of electrical charge) are exchanged in electro-chemical reactions.
• William Crookes (1879): Cathode rays are made of charged atoms.
• J.J Thomson (1897): Cathode rays are made of particles lighter than atoms and can be deflected by an negative electric field. Atoms are divisible. Corpuscles (negatively charged subatomic particles) are building blocks.
• Discovery of the Electron
  • Cathode Ray generates electrons. A small, relatively heavy, and positively charged body (the nucleus) must be at the center of each atoms. (Ernest Rutherford, 1907)
• Plum Pudding Model
  • Negatively-charged electrons in a positively-charged sphere.
• Nuclear Model
  • Small positively charged nucleus (most of the mass is in the nucleus). Rutherford discovered that the nuclei of other elements contain hydrogen nucleus as a building block named the proton.
• Isotopes: Atoms of the same element that differ in mass.

Neils Bohr (1913)

• Planetary Model
  • Electrons in orbit around a nucleus (account for stability of electrons)

Erwin Schrodinger & Werner Heisenberg (1913)

• Quantum Mechanical Model (accepted)
  • Electrons most probably in this region (uncertainty in location or momentum of electrons)

James Chadwick (1932)

• Discovered the Neutron
  • There are neutrons in the nucleus.
  • Atoms have a nucleus that contains protons and neutrons (electrons move around the nucleus)

Modern Atomic Model

• Based on Schrodinger’s mathematical model of waves: probability map of where electron is found.
• Orbitals: 3D region in space where electrons are likely to be found.
• Principal Energy level: As this energy level increases, the orbital extends further from the nucleus.
  • n = 1: One 1s orbital = 2 electrons
  • n = 2: 2s orbital and three 2p orbitals = 8 electrons
  • n = 3: 3s orbital, three 3p orbitals, and five 3d orbitals = 18 electrons
  • n = 4: 4s orbital, three 4p orbitals, five 4d orbitals, & seven 4f orbitals = 32 electrons
• Sublevels
  • s: Spherical = 2 electrons
  • p: Dumbbell = 6 electrons
  • d: Clover = 10 electrons
  • f: Flower = 14 electrons

Electron Configuration of the Periodic Table

• Number of the column in the s, p, d, and f blocks is the same as the number of electrons allowed in each sublevel.
• Number of columns = number of electrons allowed in each sublevel

Orbital Diagram

• Diagram that represents the electronic structure of an atom.
• Arranged according to energy levels:
  • Electrons are represented by up and down arrows.
  • Order of energy level of orbitals: s, p, d, f.
• Hund’s Rule: Electrons are added to a shell in a way to give the maximum number of unpaired electrons.

Electron Configuration

• Electronic configuration of the periodic table.

Explore the properties of homogenous solutions and the classification of matter in this engaging quiz. Learn about saturated, unsaturated, and supersaturated solutions, as well as physical and chemical changes crucial to understanding chemistry. Test your knowledge about solutes, solvents, and measurement properties.