Structure of Water and Hydrogen Bonds Flashcards
What is the molecular structure of a water molecule?
A water molecule (H₂O) has one oxygen atom bonded to two hydrogen atoms in a bent shape.
What is water’s polarity?
Water has a positive and a negative side due to its shape and electronegativity difference, making it polar.
Why is hydrogen bonding important in water?
Hydrogen bonds make water molecules stick together, creating a stable liquid environment for life.
What is specific heat capacity in water?
Water absorbs a lot of heat with little temperature change, keeping environments and organisms st
What type of bonds connect the atoms in a water molecule?
Covalent bonds connect oxygen to hydrogen atoms in a water molecule by sharing electrons.
What are lone pairs in a water molecule?
Lone pairs are unshared electrons on the oxygen atom, giving water a bent shape and contributing to its polarity.
What is a hydrogen bond?
A hydrogen bond is a weak attraction between the partially positive hydrogen of one water molecule and the partially negative oxygen of another.
Why are hydrogen bonds important for water’s properties?
Hydrogen bonds create cohesion, adhesion, surface tension, high heat capacity, and allow water to be a liquid at room temperature.
What is a meniscus?
A meniscus is the curved surface of water in a container due to adhesion of water to the container walls and cohesion among water molecules.
What causes a concave meniscus?
A concave meniscus forms when water molecules are more attracted to the walls of a container than to each other.
What causes a convex meniscus?
A convex meniscus forms when a liquid, like mercury, is more attracted to itself than to the container walls.
What is surface tension, and how does it relate to hydrogen bonds?
Surface tension is the tight surface layer formed by water molecules at the surface due to hydrogen bonds pulling them together.
How does water’s polarity contribute to hydrogen bonding?
Water’s polarity creates partial positive (hydrogen) and negative (oxygen) ends, allowing them to form hydrogen bonds with other polar molecules.
What role do lone pairs on oxygen play in water’s properties?
Lone pairs on oxygen create areas of partial negative charge, essential for forming hydrogen bonds with other water molecules.
What is the difference between cohesion and adhesion in water?
Cohesion is water molecules sticking to each other; adhesion is water molecules sticking to other surfaces.
How does hydrogen bonding affect water’s boiling and freezing points?
Hydrogen bonds require significant energy to break, raising water’s boiling point, and form a lattice structure when freezing, lowering its density.
Why does ice expand when it freezes?
Hydrogen bonds form a structured lattice in ice, spreading water molecules apart and making ice less dense than liquid water.
How do hydrogen bonds contribute to capillary action?
Hydrogen bonds allow water to stick to itself (cohesion) and to other surfaces (adhesion), enabling water to move up thin tubes against gravity.
What does “hydrophilic” mean?
Hydrophilic means “water-loving”; it describes substances that dissolve well in water, like salts and sugars, due to their polarity or charge.
What does “hydrophobic” mean?
Hydrophobic means “water-fearing”; it describes substances that do not dissolve well in water, like oils and fats, due to their non-polar nature.
What is a solvent?
A solvent is a substance that dissolves other substances (solutes). Water is known as the “universal solvent” because it dissolves many polar and ionic substances.
What is a solute?
A solute is a substance that is dissolved in a solvent. For example, salt is a solute when dissolved in water.
How does water act as a solvent in biological systems?
Water dissolves ions and polar molecules, allowing chemical reactions to occur and substances to be transported in cells and organisms.
What are examples of hydrophilic substances?
Examples include salt (NaCl), sugar, and many proteins, which dissolve well in water due to their polarity or ionic nature.
