1.2.1 Properties of Water

• Water molecules are composed of one oxygen atom bonded to two hydrogen atoms.
• The oxygen atom in a water molecule has a slight negative charge, while the hydrogen atoms have slight positive charges.
• Steps in the formation of hydrogen bonds between water molecules.

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

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

  3️⃣ A weak hydrogen bond forms between the two molecules
• Hydrogen bonds in water contribute to its high specific heat capacity, which helps maintain stable temperatures in organisms.
• High heat capacity is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.
• Water's high heat capacity is due to the energy needed to break or weaken hydrogen bonds.
• Match the biological importance of water with its effect:

  Thermal Stability ↔️ Maintains stable body temperatures

  Environmental Buffer ↔️ Aquatic habitats experience gradual temperature changes

  Cellular Processes ↔️ Prevents rapid temperature fluctuations
• The oxygen atom in a water molecule carries a slight negative charge, while the hydrogen atoms carry slight positive charges.
• Water molecules form hydrogen bonds with each other due to their polarity.
• Arrange the key features of water molecules in their correct order:

  1️⃣ Composition: One oxygen atom bonded to two hydrogen atoms

  2️⃣ Polarity: Unequal electron sharing creates $δ +$ and $δ−$ charges

  3️⃣ Hydrogen Bonding: $δ +$ hydrogens attract $δ−$ oxygen of another
• What is the charge on the oxygen atom in a water molecule due to uneven electron distribution?

  $δ−$
• Hydrogen bonds in water form between the $δ +$ hydrogen of one molecule and the $δ−$ oxygen of another, creating a weak intermolecular force
• Water molecules are nonpolar due to equal electron sharing between oxygen and hydrogen atoms.

  False
• What type of interaction occurs between the $δ +$ hydrogen of one water molecule and the $δ−$ oxygen of another?


  Hydrogen bonding
• Hydrogen bonds form because oxygen is more electronegative than hydrogen, creating a dipole moment.
• Steps in the formation of hydrogen bonds between water molecules

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

  2️⃣ The $δ +$ hydrogen of one molecule attracts the $δ−$ oxygen of another

  3️⃣ A weak hydrogen bond forms between the two molecules
• Cohesion in water allows insects to walk on its surface.
• Why does water's high specific heat capacity help maintain stable temperatures in aquatic environments?

  Breaks hydrogen bonds
• Water's solvent properties enable it to dissolve polar substances for transport and reactions
• Match the property of water with its underlying cause:

  High heat capacity ↔️ Strong hydrogen bonds

  High heat of vaporization ↔️ Energy required to break hydrogen bonds

  Universal solvent ↔️ Polarity of water molecules
• High heat capacity is the heat required to raise the temperature of one gram of a substance by one degree Celsius.
• Why does water's high heat capacity require more heat to raise its temperature?

  Breaks hydrogen bonds
• Water's high heat capacity acts as an environmental buffer, supporting marine life
• The high heat of vaporization of water is due to the energy needed to break hydrogen bonds.
• What is the definition of heat of vaporization?

  Energy to convert liquid to gas
• The evaporation of water aids in cooling organisms through processes like perspiration
• Why is water referred to as a universal solvent?

  It dissolves polar substances
• Water dissolves ionic compounds by hydrating individual ions.
• Water dissolves polar compounds by forming hydrogen bonds with them.
• What is the formula to measure the solubility of a substance in water?

  $S =$$\frac{Mass}{Volume}$
• Match the molecular feature of water with its description:

  Molecular Formula ↔️ H_{2}O</latex>

  Polarity ↔️ Oxygen is more electronegative

  Bonds ↔️ Covalent bonds between O and H
• What is the dipole moment of water caused by?

  Uneven electron distribution
• The first step in the formation of hydrogen bonds is the polarization of water molecules.
• Hydrogen bonds form between the hydrogen of one water molecule and the oxygen of another.
• The first step in the formation of hydrogen bonds is polarization of water molecules.
• Steps in the formation of hydrogen bonds

  1️⃣ Polarization of water molecules

  2️⃣ Attraction between δ+ and δ- charges

  3️⃣ Formation of hydrogen bond
• Why does water have a high heat capacity?

  Hydrogen bonds
• Hydrogen bonds require energy to break, contributing to water's high heat capacity.
• The high heat capacity of water helps maintain thermal stability for organisms.
• What is the high heat of vaporization of water primarily due to?

  Hydrogen bonds