Compounds

• 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 is the composition of a water molecule?

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

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

  Substances with two or more different elements
• Why is water classified as a compound?

  It contains hydrogen and oxygen elements
• What is a key feature of compounds regarding element proportions?

  Elements are always in the same proportions
• What is the chemical formula for water?

  H₂O
• 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 the formula H₂SO₄ represent?

  Sulfuric acid with specific atom counts
• How do brackets function in chemical formulas?

  They group atoms and indicate quantity
• What is the formula for calcium hydroxide?

  Ca(OH)₂
• What distinguishes large compounds from small molecules?

  Large compounds have ionic bonds
• What is the formula for sodium chloride?

  NaCl
• How do ionic bonds affect the structure of sodium chloride?

  They form large structures, not molecules
• What does the formula NaCl represent in terms of ratio?

  One sodium ion to one chloride ion
• What is a mixture?

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

  Using physical methods like filtration
• What would happen if you mixed oxygen molecules and sodium chloride?


  It would create a mixture of substances
• Why are mixtures easy to separate?

  They lack chemical bonds between substances