Structure of Water and Hydrogen Bonding - AP Biology
- Which type of bond holds the hydrogen and oxygen atoms together in a water molecule?
- Covalent bond. Electrons are shared between atoms within the molecule.
- What is the structural shape of a water molecule?
- Bent or V-shaped. Lone pairs on oxygen create angular geometry.
- What is the angle between the hydrogen atoms in a water molecule?
- 104.5 degrees. The bent molecular geometry creates this specific bond angle.
- Which property of water allows it to form droplets on leaves?
- Cohesion. Intermolecular attraction pulls molecules into spherical shapes.
- Why is the specific heat of water important for aquatic life?
- It stabilizes temperatures in aquatic environments. Prevents harmful temperature swings in aquatic habitats.
- Which property of water helps maintain homeostasis in organisms?
- High heat capacity. Prevents rapid temperature changes that could harm cells.
- What type of molecule is water due to its unequal distribution of charges?
- Polar molecule. Unequal electron distribution creates positive and negative ends.
- Which property of water is involved in sweating as a cooling mechanism?
- High heat of vaporization. Large energy requirement for evaporation removes body heat effectively.
- What is the cause of water's lower density in solid form compared to liquid?
- Hydrogen bonds form a lattice in ice. Rigid crystal structure creates spaces, reducing density.
- Why does water have a high heat of fusion?
- Due to hydrogen bonding. Energy required to break bonds during melting phase transition.
- What is the molecular formula for water?
- H₂O. Contains two hydrogen atoms and one oxygen atom.
- What is the reason for water's high heat of vaporization?
- Hydrogen bonding. Energy required to break multiple hydrogen bonds during vaporization.
- What is the role of hydrogen bonds in water's high heat capacity?
- They absorb heat when breaking and release heat when forming. Energy storage in bond formation/breaking moderates temperature change.
- What describes the ability of water to resist changes in temperature?
- Thermal stability. High heat capacity prevents rapid temperature fluctuations.
- What kind of interaction is primarily responsible for water's cohesive properties?
- Hydrogen bonding. Intermolecular forces between water molecules.
- What type of bond forms between water molecules?
- Hydrogen bond. Forms between the partial positive H and partial negative O of adjacent molecules.
- What is the term for the attraction between water molecules and other substances?
- Adhesion. Water molecules attract to different polar or charged surfaces.
- Which term describes water's ability to dissolve many substances?
- Universal solvent. Polarity allows it to dissolve ionic and polar substances.
- What is the primary reason ice floats on water?
- Ice is less dense due to hydrogen bonding. Crystal structure in ice creates less dense arrangement than liquid.
- Identify the partial charges on oxygen and hydrogen in water.
- Oxygen is partially negative; hydrogen is partially positive. Oxygen pulls electrons more strongly, creating polarity.
- What causes the meniscus seen in a graduated cylinder with water?
- Adhesion. Water molecules attract to glass surfaces more than to each other.
- What is responsible for water's high surface tension?
- Cohesion due to hydrogen bonding. Intermolecular attraction creates resistance at the surface.
- Which property of water contributes to its role in chemical reactions?
- Solvent properties. Dissolves reactants and facilitates molecular interactions.
- Which property of water allows insects to walk on its surface?
- Surface tension. Cohesive forces create a strong interface between water and air.
- What allows water to adhere to plant cell walls?
- Adhesion. Attraction between water and polar cell wall components.
- How many hydrogen bonds can a single water molecule form?
- Four hydrogen bonds. Two from hydrogens and two from lone pairs on oxygen.
- Which feature of water allows it to stabilize temperature in environments?
- High heat capacity. Hydrogen bonds absorb energy during temperature fluctuations.
- What property of water leads to surface tension?
- Cohesion. Attraction between water molecules creates surface resistance.
- Which property of water helps in nutrient transport in organisms?
- Solvent properties. Polarity allows dissolution and transport of nutrients.
- Why is water considered a polar molecule?
- Unequal sharing of electrons between oxygen and hydrogen. Oxygen's higher electronegativity creates charge separation.
- What is the charge distribution in a water molecule?
- Polar, with partial negative on oxygen and partial positive on hydrogens. Electronegativity difference creates dipole moment.