Unit 1

Water Molecule

Water Molécule

Water Molécule

A polar molecule made of 1 oxygen atom and 2 hydrogen atoms

Polarity

Having positively and negatively charges areas bc of an uneven distribution of electrons

Negative Poles

Areas with more electron, around the oxygen atom

Positive pole

Area with fewer electrons, near the hydrogen atom nuclei

Hydrogen bonds

A weak bond formed between polar water molecules

Why is cohesion High in water?

H-bonds make water molecules stick to each other more strongly. It causes surface tension.

What is waters density lower when frozen (ice)?

The extra h-bonds cause cold water molecules to move apart slightly

Why does water have high specific heat?

Some heat is used to break h-bonds so more is needed to raise the water temp.

Why is water an excellent solvent?

Bc polar water molecules dissolve so many substances.

Why does water have dipolarity?

Bc water molecules contain both positive and negative charges.

Why is water a good coolant in sweat?

Because it has a high specific heat

Why is water good for transport?

It can easily dissolve glucose, sodium chloride, oxygen, and many amino acids.

Why is water a medium for life?

• 1st cells formed when h20 became enclosed in membrane

• Substances can be dissolved within it + chem. Rc happen

• It makes up 60% of human life

• Transport mat. In and out of cell

• Most molecules are dissolved within H2O

• Makes up cytoplasm a of cells and internal space of organelles

• Provides medium for org, in lakes, rivers, and ponds

How are H2O molecules together?

By polar covalent bonds

What are properties of water?

• cohesion

• adhesion

• Buoyant

• Viscous

• High specific heat

• High thermal conductivity

Why does water molecules have great adhesion?

Other molecules are polar molecules and bond due to the H-bonds

Example of water’s cohesion

1. Conduction of water under tension in xylem; H20 sucked up from roots through the stems to the leaves in vessels classed xylem tissue

2. Water surface as a habitat due to surface tension

What is surface tension?

Elastic membrane at the top of bodies of water, which allow organisms to float on the top of the water and that helps them thrive in environment.

Example of water adhesion

1. Water adheres to chemicals in soil. Capillary actions draw water from soil to roots

2. Water adheres to cellulose in cell walls, drawing water from xylem to keep cell walls moist.

Benefit of water having high specific heat. Why is it useful?

Water can absorb and give off heat without much change in temperature because of the large amount of energy needed to do so that it doesn’t have.

• Moderates temp or earth

• And stay at consistent temp even on colder nights

What is thermal conductivity?

The rate at which heat passes through a material.

What is buoyancy?

Density of an object lower than density of water, object will float

How are ringed seals (Pusa Hispida) against the prop. Of water?

Buoyancy- keeps snout above water to breath, however when diving expels water

Viscosity- paddle like feet and streamlined body assist in in moving through water while swimming

Thermal conductivity- minimize heat loss through the use of 10cm thick blubber in skin

How is a black throated loon (Gavin Attica) against the properties of water?

Buoyancy- spends a lot of time at the surface and depend on the buoyancy to stay up

Viscosity- requires energy to overcome viscosity, webbed feet and streamlined body aides this

Thermal conductivity- lose lots of heat to water bc of high TC so they spread the oil form glands at the tail using their beaks to water proof feathers, reducing heat loss.