Chemistry Study Notes: Observations and Particles

Chemistry Study Notes

• Observations vs. Inferences:
  • Observation: Using senses to learn about objects, events, and their properties.
  • Inference: Drawing conclusions based on evidence and reasoning.
  • Observations are used to collect data for developing and testing hypotheses.
  • Inferences explain phenomena using data.

Particle Theory

• Particle Theory of Matter: All matter is made up of tiny indivisible particles.
  • Particles are too small to be seen.
  • This theory explains matter's behaviour.

Pure Substances vs. Mixtures

• Pure Substances: Made of only one type of particle; have a fixed structure.
  • Used to measure properties accurately and for chemical reactions without impurities.
• Mixtures: Combinations of two or more substances in varying proportions.
  • Used in many everyday processes, like cooking, cleaning, and medicine.

Solutions

• Solutions: Homogeneous mixtures of two or more substances.
  • Used to separate and purify materials, and to carry out chemical analysis.

Compounds

• Compounds: Substances made of two or more different elements combined in a fixed ratio.
  • The elements react and form strong bonds.
  • Requires significant energy to break apart.
  • Difference between pure substances and mixtures lies in how the components are joined

Homogeneous vs. Heterogeneous Mixtures

• Homogeneous Mixture: Uniform composition throughout the mixture.
• Heterogeneous Mixture: Non-uniform composition throughout the mixture.
• Mechanical Mixture: Two or more particle types not mixed evenly.

Physical and Chemical Properties

• Physical Property: Characteristic observed and measured without changing substance identity.
  • Used to describe changes in momentary states.
• Chemical Property: Characteristic observed during a chemical reaction.
  • Used for building chemical classifications.

Examples of Properties

- Physical properties: Colour, Hardness, Malleability, Weight, Electrical Conductivity, Solubility, Mass
- Chemical properties: Flammability, Toxicity, Acidity, Reactivity, Heat of Combustion

Quantitative and Qualitative Properties

• Quantitative Property: Measured and described with numbers
• Qualitative Property: Observed but not numerically measured.

Physical vs. Chemical Change

• Physical Change: Change in physical properties, not changing the substance's identity.
• Chemical Change: Change in materials to form new substances with different properties.

Testing for Unknown Gases

• Oxygen: Relights a glowing splint
• Hydrogen: Causes a lit splint to burn with a 'squeaky pop'.
• Carbon Dioxide: Turns limewater cloudy

Chemical Word Equations

• Reactants: Starting materials written on the left side of the equation.
• Products: Results of the reaction, written on the right side of the equation

Periodic Table Trends

• Patterns in the periodic table showing aspects of elements (size, electronic properties).
• Used to predict element properties.

Subatomic Particles

• Subatomic Particles: Particles smaller than an atom
  • Charge, Mass, and Spin
  • Types: Electrons (-), Protons (+), Neutrons (0)
  • Location: Electrons (outside nucleus), Protons & Neutrons (inside nucleus).
  • Mass values for each particle
  • Charge values for each particle

Bohr-Rutherford Diagrams

• Model for visualizing electrons orbiting the nucleus.

Neutral Atoms

• Atoms with no net electric charge (equal number of protons and electrons).

Isotopes

• Variations of an element with the same number of protons but different number of neutrons.

Standard Atomic Notation

• Way to represent atoms with element symbol, mass number, and atomic number.
  • Used to show important information about an atom, like its element, number of protons, and total number of protons and neutrons. It helps identify different isotopes of the same element.

Chemical Formulas

• Represent substances using symbols and numbers, showing the elements and the number of atoms.
  • Used to describe the composition of a chemical substance.

Binary Ionic Compounds

• Compounds composed of a metal cation and a nonmetal anion held together by ionic bonds.

Explore the fundamental concepts of chemistry, including observations vs. inferences, the particle theory of matter, and the distinction between pure substances and mixtures. This quiz will test your understanding of these core topics, essential for mastering chemistry.