Water Molecule Flashcards

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Questions and Answers

Draw a water molecule - label the atoms and the charge on them.

See diagram

Describe the structure of a water molecule.

One atom of Oxygen joined to two atoms of hydrogen by shared electrons in a covalent bond.

Name the bond that can link two water molecules together.

A hydrogen bond

Explain what a hydrogen bond is, which types of atoms it can join together and where they occur in biology.

An electrostatic bond between a more electronegative atom (e.g. O) and a hydrogen atom bonded to another electronegative atom. They occur in water. Signup and view all the answers

Draw two water molecules and draw and label the bond that links them together.

See diagram Signup and view all the answers

Define the term 'polar'.

Unequal sharing of electrons in a water molecule. It has a partially negative charge on one side (O) and a partially positive charge on the other side (H2). Signup and view all the answers

Explain why water is a polar molecule.

The oxygen is more electronegative, so it attracts the H electrons towards it, giving O a partially negative charge and leaving the H with a partially positive charge. Signup and view all the answers

Define the term 'electronegativity'.

A measure of the tendency of an atom to attract a bonding pair of electrons. Signup and view all the answers

Define the term 'dipole'.

A molecule that has both positive and negative charges, separated by a small distance, due to uneven distribution of charges. Signup and view all the answers

List the roles water plays in life (5).

<ol> <li>Reactant in important chemical reactions. 2. Solvent (most biological reactions take place in solution). 3. Transport medium for substances (as it's a liquid and a solvent). 4. Helps with temp control (high specific heat capacity and high latent heat of vaporization). 5. Habitat.</li> </ol> Signup and view all the answers

Using the 'polar nature of water,' explain how 1) the water can dome above the level of the glass container it is in, 2) the shape of the meniscus in a glass measuring cylinder, and 3) capillary action in a narrow glass tube.

<ol> <li>Cohesion between water molecules causing surface tension due to H bonds. 2) Adhesion to sides of the container draws molecules up. 3) Cohesion between water molecules and adhesion to other molecules means water moves up narrow spaces e.g., xylem.</li> </ol> Signup and view all the answers

List examples of how water is used from across the whole diversity of life (10).

<ol> <li>Habitat. 2. Sexual Reproduction. 3. Lubricant. 4. Transparency (to see underwater). 5. Solvent. 6. Transport medium. 7. Support. 8. Reactant. 9. Thermal stability. 10. Cooling.</li> </ol> Signup and view all the answers

Describe any other properties water has that makes it useful for life (3).

<ol> <li>Transparency. Allows photosynthesis to occur and allows vision to play a role for aquatic organisms. 2. Lubrication. Internal organs can move against each other without damage as they are surrounded by fluid. Synovial fluid prevents bone scraping. 3. Sexual Reproduction. Sperm need to swim to the egg either in semen or in water for external reproduction.</li> </ol> Signup and view all the answers

Define the term 'hydrophilic'.

Attracted to water. Signup and view all the answers

Define the term 'cohesion'.

The tendency of molecules of the same kind to stick/bind together. Signup and view all the answers

Define the term 'hydrophobic'.

Repels water. Signup and view all the answers

Define the term 'adhesion'.

The tendency of molecules to bind to different types of molecules. Signup and view all the answers

Why does the polar nature of water allow it to be a useful solvent?

Water H-bonds with the solutes (only if they're polar/charged) instead of them bonding with each other, so they dissolve. Signup and view all the answers

Why does the polar nature of water allow it to be a useful transport medium?

Water is a solvent and a liquid. It has high latent heat evaporation which means it is difficult for water to change states as it takes a lot of energy to break the H-bonds between the molecules. Signup and view all the answers

Why does the polar nature of water allow it to be a useful coolant?

Water has high latent heat evaporation so a lot of energy is used up when water evaporates. When sweat evaporates, it cools the skin. Signup and view all the answers

Why does the polar nature of water allow it to be a useful reactant?

Solvent? Hydrolysis reactions? Signup and view all the answers

Why does the polar nature of water allow it to be a useful habitat?

The H-bonding results in surface tension. Water is less dense as it cools so ice floats, this is because the H-bonds make a lattice. Water is a solvent. Water has a high specific heat capacity. Signup and view all the answers

Study Notes

Water Molecule Structure

A water molecule consists of one oxygen atom and two hydrogen atoms connected by covalent bonds.
Water molecules exhibit polar properties due to unequal sharing of electrons, resulting in partial charges.

Hydrogen Bonds

Hydrogen bonds form between a more electronegative atom (e.g., oxygen) and a hydrogen atom connected to another electronegative atom.
These bonds are crucial in biological structures, influencing the properties of water and other biomolecules.

Polarity of Water

Water is polar with a partially negative charge on oxygen and partially positive charges on the hydrogen atoms.
The electronegativity of oxygen pulls hydrogen's electrons closer, leading to a dipole formation.

Properties of Water

Water acts as a reactant in essential chemical reactions and serves as a solvent for biological processes.
It supports transport of substances, temperature regulation through high specific heat capacity, and provides habitat for various organisms.

Cohesion and Adhesion

Cohesion allows water molecules to stick together, generating surface tension which can lead to phenomena such as water doming over glass.
Adhesion enables water to interact with different substances, influencing meniscus shape in containers and aiding capillary action in plants.

Usage of Water in Life

Water plays diverse roles including habitat, transport medium, lubricant, and reactant in various biochemical processes.
It provides transparency for photosynthesis, enables sexual reproduction by allowing movement of sperm, and contributes to thermal stability.

Hydrophillic and Hydrophobic Properties

Hydrophillic substances are attracted to water, facilitating solubility and interaction with biological systems.
Hydrophobic substances repel water, affecting how organisms interact with their environments.

Electronegative Measurements

Electronegativity measures an atom's ability to attract bonding pairs of electrons, impacting molecular interactions.

Cooling and Stability

Water's high latent heat of evaporation makes it an effective coolant, absorbing significant heat energy during evaporation, such as through sweating.
The high specific heat capacity allows water to maintain stable temperatures, which is critical for life.

Role in Reactions

Water participates in hydrolysis reactions, acting as a reactant that can break down complex molecules.

Habitat and Ecosystem

Water's hydrogen bonding leads to phenomena like surface tension and the floating of ice, which protects aquatic ecosystems by insulating water below.

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Description

This quiz focuses on the structure and bonding of water molecules. You will explore the composition of water, including related vocabulary like hydrogen bonds. Ideal for students studying chemistry concepts related to molecular structure.