a1.1 water Flashcards
(44 cards)
Where did the first cells originate?
In water
Why is water essential for life?
- Universal solvent
- Facilitates chemical reactions
- Regulates temperature
- Supports cellular transport
What is the structure of an atom?
Atoms consist of a nucleus (protons + neutrons) and orbiting electrons.
How do ionic and covalent bonds differ?
- Ionic Bonds: Electrons are transferred, forming charged ions.
- Covalent Bonds: Electrons are shared between atoms.
What is a polar covalent bond?
A covalent bond where electrons are unequally shared, causing partial charges.
Where is the polar covalent bond in a water molecule?
Between oxygen and hydrogen atoms.
What are the partial charges in a water molecule?
Oxygen is partially negative (-δ), while hydrogen is partially positive (+δ).
Why do hydrogen bonds form in water?
Opposite partial charges cause weak attractions between molecules.
What are the consequences of hydrogen bonding in water?
- High boiling & melting points
- Cohesion (water sticking to itself)
- Adhesion (water sticking to surfaces)
- Strong solvent properties
What is cohesion?
Water molecules sticking together due to hydrogen bonding.
How does cohesion help plants?
Moves water up the xylem in vascular plants.
What causes surface tension?
Cohesion creates a “film” on the water’s surface.
How does surface tension benefit organisms?
Helps insects like water striders walk on water.
What does “polar” mean?
A molecule with uneven charge distribution, leading to partial positive and negative regions.
What is adhesion?
Water molecules sticking to polar or charged surfaces.
What is an ion?
A charged particle formed when an atom gains or loses electrons.
How do cations and anions differ?
- Cation: Positively charged ion
- Anion: Negatively charged ion
Why does water attract polar and charged molecules?
Partial charges in water allow interactions with other charged surfaces.
What causes capillary action?
Adhesion and cohesion allow water to move against gravity in thin tubes.
How does capillary action function in plant tissue?
Water climbs the xylem via adhesion to cell walls and cohesion between water molecules.
How does capillary action affect soil?
It distributes water through tiny pores in soil, enabling plant absorption.
What are solutes and solvents in a solution?
- Solvent: Substance that dissolves other materials
- Solute: Substance being dissolved
What is solvation?
The process of dissolving a solute into a solvent.
Why can water dissolve polar and charged molecules?
Water’s polarity allows hydration shells to form around solutes, stabilising them.
