Chemical Amounts

Importance of Chemistry

• Chemistry is central and impacts many aspects of life: food, energy, drugs, textiles, health, etc.

Introduction - Chemical Amounts

• Statement of inquiry: Chemical interactions help predict how much can be made or used.
• Key concept: Relationships.
• Related concept: Interaction / Balance.
• Global context: Scientific and technical innovation.

Learning Objectives

• Define a molecule.
• Define a molecular formula.
• Identify the number of elements and atoms in a molecular formula.

Chemical Formula

• Representation for a chemical compound or molecule.
• Uses element symbols from the periodic table.
• Subscripts indicate the number of atoms of each element.

Examples

• Water: H_2O (2 Hydrogen, 1 Oxygen).
• Sodium Chloride: NaCl (1 Sodium, 1 Chlorine).
• Sulfuric Acid: (H2SO4)

Importance of Subscripts

• Different subscripts change the compound (e.g., H2O vs. H2O_2).

Key Definitions

• Atom: Smallest unit of matter retaining element properties.
• Composed of nucleus (protons/neutrons) and orbiting electrons.
• Element: Made of the same kind of atom.
• Compound: Two or more different elements chemically combined.
• Molecule: Two or more atoms chemically bonded (same or different).

Atomic Structure

• Atomic Number: Unique to each element, determined by the number of protons.
• Atomic Mass Number: Sum of protons and neutrons.

Elements, Molecules, and Compounds

• Elements: One type of atom.
• Molecules: >1 type of atoms.
• Compounds: >1 type of atoms.

Chemical / Molecular Formulas

• Examples: CO2, H2O, NaCl, NH3, C2H5OH, Mg(OH)2