Water and its properties

Question 1

What is the most stable, polar molecule on Earth? Describe the covalent bond with this molecule

Answer 1

WATER. asymmetric covalent bond, as Hydrogen atoms have partial positive charge and oxygen has partial negative charge (since e- density shifted towards more electronegative atom, oxygen also larger nucleus). water is polar and forms tetrahedron orientation of O2 electrons (not involved in bonding) form angle between covalent bonds.

Question 2

What molecule is the closest analog to Water?

Answer 2

H2S, which is a nonpolar molecule. Sulfur has a lower electronegativity than oxygen due to its distance from nucleus and lower propensity of pulling e- away from hydrogen, hence not polar. to Take polar molecule (with symmetric bonds), need element closest to nucleus, 4 orbital shell.

Question 3

What leads to the great stability of water?

Answer 3

Water molecules have a strong binding force, so spontaneous decay is unlikely to occur. Hydrogen is the smallest atom that can either lose or donate electron. once electron is donated, uncompensated nuclear positive charge is very strong (hard to create), and any shift in e-density in molecule is counteracted through intramolecular compensation with opposing hydrogen. Water also has lower chance of breaking apart compared to HF.

Question 4

Define Hydrogen bonds. How many H-bonds can water form?

Answer 4

Hydrogen bonds are electrostatic (polar) attractions between two electronegative atoms. H-bonds are WEAK intermolecular interactions that can easily be broken by heat.
They are NONCOVALENT bonds.
Ex: N-H-O
Water can form 4 hydrogen bonds with other water molecules.

Question 5

Name the unique properties of water

Answer 5

1. most stable polar solvent in the universe
2. highest specific heat capacity of all liquids, greatest thermal conductivity, highest thermal surface tension (large number of H-bonds it can form)
   3, water has broad range of liquid stability (remain liquid in many places, room temp)
3. optically clear
4. solid water (ice) is LESS DENSE than liquid water (expands upon freezing by 9%; h-bonds become more arranged and stable as water freezes)

Question 6

what makes water a great solvent?

Answer 6

Water can dissolve a variety of substances including hydrophilic molecules due to its polarity. Polar molecules like water can also break ionic bonds.

Question 7

What are Hydrated ions?

Answer 7

major solutes like cations inside the cells that define the environment where other biomolecules reside and bioelectric currents.

Question 8

What are Hydrophilic molecules ?

Answer 8

substances that readily dissolve in water. these include ions and polar molecules that attract H2O molecules through electric charge effects.

ionic substances (NaCl) dissolve because water is attracted to + charge (Na+) or negative (Cl-) of each ion.
Polar molecules dissolve because their molecules forms hydrogen bonds with water.