Overview
This lesson reviews the organization of matter, the structure and use of the periodic table, the composition and naming of compounds, and introduces chemical reactions.
Matter and Its Organization
- Matter is anything with mass and volume (takes up space).
- Matter consists of elements (pure substances) and compounds (combinations of elements).
- Compounds are made from two or more elements in fixed ratios and can only be separated chemically.
- Mixtures are physical combinations with no fixed ratio and can be separated by physical means.
Basic Atomic Structure
- Atoms have three subatomic particles: electrons (negative, orbit nucleus), protons (positive, in nucleus), and neutrons (neutral, in nucleus).
- The nucleus contains protons and neutrons (nucleons), which define atomic mass.
- The atomic number equals the number of protons; atomic mass is protons plus neutrons.
- Number of neutrons = atomic mass - atomic number.
The Periodic Table
- Elements are arranged by atomic number.
- Metals are on the left, non-metals on the right, and semi-metals (metalloids) along the zigzag line.
- Properties: metals are shiny, conduct heat/electricity, and malleable; non-metals are dull, poor conductors, and brittle.
- Columns (groups) indicate similar chemical properties; rows (periods) run horizontally.
- Groups to remember: Group 1—alkali metals, Group 2—alkaline earth metals, Group 17—halogens, Group 18—noble gases.
- Seven diatomic elements: Iodine, Bromine, Chlorine, Fluorine, Oxygen, Nitrogen, Hydrogen.
Compounds and Chemical Naming
- Compounds have chemical formulas (e.g., H₂O, CO₂) showing element ratios.
- Prefixes (mono-, di-, tri-) are used for compounds with only non-metals.
- For compounds with a metal and non-metal, no prefix is used (e.g., magnesium chloride).
- The element more to the left is named first.
- Important groups: hydroxide (OH), nitrate (NO₃), carbonate (CO₃), sulfate (SO₄), sulfite (SO₃), phosphate (PO₄).
Chemical Reactions
- Chemical reactions transform substances into new substances with different properties.
- Reactants (starting materials) are written on the left; products (new substances) on the right, separated by an arrow (→).
- Chemical reactions can be written in words, formulas, or shown with particle diagrams.
Key Terms & Definitions
- Matter — everything that has mass and volume.
- Element — a pure substance made of one type of atom.
- Compound — a substance formed when atoms of two or more elements chemically bond in fixed ratios.
- Atom — the smallest unit of matter, made of protons, neutrons, and electrons.
- Group — a column on the periodic table with elements of similar properties.
- Period — a horizontal row on the periodic table.
- Diatomic element — molecules made of two identical atoms.
- Chemical reaction — a process that changes substances into new substances.
Action Items / Next Steps
- Review the periodic table and practice locating elements, their groups, and periods.
- Memorize the seven diatomic elements.
- Study common compound groups: hydroxide, nitrate, carbonate, sulfate, sulfite, phosphate.
- Attempt practice exercises: identify metals/non-metals/semi-metals; name and write formulas for compounds.
- Prepare for next lesson: balancing chemical equations.