Compounds, molecules and mixtures

• What are the three important terms to understand about atoms?

  Molecules, mixtures, and compounds
• How is a molecule defined?

  A group of two or more atoms bonded together
• What is an example of a molecule in the air?

  Oxygen
• Can molecules contain multiple different elements?

  Yes, they can contain different elements
• What is the composition of a water molecule?

  One oxygen and two hydrogen atoms
• What is an example of a molecule that contains multiple elements?

  Water
• Why is helium not considered a molecule?

  It exists as a single atom
• What defines a compound?

  Substances with two or more different elements
• What is the formula for water?

  H₂O
• How are the elements in a compound always found?

  In the same proportions
• What does the subscript in a chemical formula indicate?

  The number of atoms of that element
• What is the formula for carbon dioxide?

  CO₂
• What does H₂SO₄ represent?

  Sulfuric acid
• How do brackets function in chemical formulas?

  They group atoms together for counting
• What is the formula for calcium hydroxide?

  Ca(OH)₂
• What is a characteristic of large compounds like sodium chloride?

  They contain millions or billions of atoms
• What is the formula for sodium chloride?

  NaCl
• Why do ionic bonds lead to large structures?

  They form large substances, not molecules
• How is the formula for sodium chloride used?

  It acts as a ratio of ions
• What is a mixture?

  Two or more substances not chemically combined
• How can mixtures be separated?

  Using physical methods like filtration
• What is an example of a method to separate mixtures?

  Filtration
• What are the key differences between molecules, compounds, and mixtures?

  • Molecules: Groups of two or more atoms bonded.
  • Compounds: Substances with two or more different elements.
  • Mixtures: Two or more substances not chemically combined.
• What are the characteristics of ionic compounds compared to molecular compounds?

  • Ionic compounds: Large structures, not discrete molecules.
  • Molecular compounds: Small, distinct molecules.
• What are the methods for separating mixtures?

  • Filtration
  • Crystallization
  • Distillation
• What are the three important terms to understand about atoms?

  Molecules, mixtures, and compounds
• How is a molecule defined?

  A group of two or more atoms bonded together
• What is an example of a molecule in the air?

  Oxygen
• Can molecules contain multiple different elements?

  Yes, for example, water molecules
• What elements are bonded in a water molecule?

  One oxygen and two hydrogen
• Why is helium not considered a molecule?

  It exists as a single atom
• What defines a compound?

  Substances with two or more different elements
• What is an example of a compound?

  Water
• Why is water classified as a compound?

  It contains hydrogen and oxygen elements
• What is the formula for carbon dioxide?

  CO₂
• What does the subscript in chemical formulas indicate?

  The number of atoms of that element
• What is the formula for sulfuric acid?

  H₂SO₄
• How can you identify the number of atoms in a compound's formula?

  By reading the subscripts in the formula
• What do brackets in chemical formulas signify?

  Grouping of atoms with a multiplier
• What is the formula for calcium hydroxide?

  Ca(OH)₂