1.2.1 Properties of Water

• What atoms are present in a water molecule?

  Oxygen and hydrogen
• Oxygen is more electronegative than hydrogen
• The oxygen atom in water carries a slight positive charge ($δ +$).


  False
• What type of bond forms between water molecules?

  Hydrogen bond
• Hydrogen bonds form because oxygen is more electronegative than hydrogen
• Steps in the formation of hydrogen bonds between water molecules

  1️⃣ Water molecules polarize, creating $δ +$ hydrogen and $δ−$ oxygen

  2️⃣ The $δ +$ hydrogen of one molecule is attracted to the $δ−$ oxygen of another

  3️⃣ A weak hydrogen bond forms between the two molecules
• What biological phenomenon is enabled by water's cohesion?

  Insects walking on water
• High heat capacity is the heat required to raise the temperature of one gram of a substance by 1°C
• Water's high heat capacity is due to its covalent bonds.

  False
• How does water's high heat capacity contribute to thermal stability in organisms?

  Maintains stable body temperatures
• In water, the oxygen atom carries a slight negative charge, denoted as $δ−$
• Match the property of water with its description:

  Polarity ↔️ Unequal sharing of electrons

  Hydrogen Bonding ↔️ Attraction between $δ +$ hydrogen and $δ−$ oxygen
• Cohesion in water allows insects to walk on its surface.
• Why is water's high heat capacity important for aquatic environments?

  Supports gradual temperature changes
• Water's high heat capacity stems from the strong hydrogen bonds between its molecules
• What type of forces are hydrogen bonds between water molecules?

  Weak intermolecular forces
• Kinetic energy of water molecules increases with temperature rise.
• Water's high heat capacity requires a large amount of heat to overcome bond strength
• Match the biological importance of water with its description:

  Thermal Stability ↔️ Maintains stable body temperatures

  Environmental Buffer ↔️ Aquatic habitats experience gradual temperature changes

  Cellular Processes ↔️ Prevents rapid temperature fluctuations
• What is the boiling point of water in Celsius?

  $100^{\circ}C$
• Water's high heat of vaporization requires energy to break hydrogen bonds.
• Thermoregulation in organisms, such as sweating, relies on water's high heat of vaporization
• Why is water called a universal solvent?

  Dissolves many substances
• Match the key properties of water with their descriptions:

  Polarity ↔️ Water molecules have positive and negative ends

  Hydrogen Bonds ↔️ Water molecules form weak bonds with other polar substances

  Dissolution of Polar Compounds ↔️ Disrupts intermolecular forces

  Dissolution of Ionic Compounds ↔️ Separates into constituent ions
• What creates the polarity of water molecules?

  Unequal sharing of electrons
• Water serves as a medium for chemical reactions in cells
• Water dissolves polar substances by forming hydrogen bonds with them.
• Water molecules are held together by covalent bonds and exhibit polarity
• What type of intermolecular force is formed between water molecules due to polarity?

  Hydrogen bonds
• Cohesion in water allows insects to walk on water's surface.
• Hydrogen bonds form between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another
• Match the biological importance of hydrogen bonds in water with their effects:

  Cohesion ↔️ Allows insects to walk on water

  High Specific Heat Capacity ↔️ Maintains stable temperatures

  Solvent Properties ↔️ Dissolves polar substances

  Structure of Biological Molecules ↔️ Stabilizes proteins and nucleic acids
• Why does water have a high heat capacity?

  Hydrogen bonds
• Water's high heat capacity helps buffer temperature changes in aquatic environments.
• Water's high heat of vaporization requires energy to break all hydrogen bonds
• What is an example of thermoregulation using water's high heat of vaporization?

  Sweating
• Water's polarity and ability to form hydrogen bonds make it a universal solvent
• Which type of compounds are dissolved by water through separation into ions?

  Ionic compounds
• What is the mechanism by which water dissolves polar substances?

  Surrounds and disrupts forces
• The polarity of water is crucial for its interaction with polar substances and ions