1. Inorganic Chemistry

2. Inorganic Chemistry
Three most common elements of life are carbon, hydrogen, and oxygen
Other elements needed by living organisms include nitrogen, sulfur, phosphorus, iron, calcium, sodium and potassium
C, O, H, and N make up 96% of living matter

3. Examples:

4. Water Water molecules are composed of two H bonded to an O
Shaped like a “V” – electrons spend more time around the O than the H
O region has a slightly (-) charge, H region has a slightly (+) charge – Polar molecule
Water molecules are attracted to each other forming hydrogen bonds

5. Hydrogen Bonding
Water molecules are attracted to each other because of polarity
hydrogen bonds form when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom
Usually occur between oxygen or nitrogen atoms in living cells

6. Why is Water so Important to Life?
All life is dependent on water (65 – 95% of all living tissue is water)
Many of water’s unique properties are due to hydrogen bonding

7. Why is Water so Important to Life?
Water is an excellent solvent because of polarity
dissolves a wide variety of substances
Ionic compounds and polar molecules dissolve easily in water – hydrophilic
Uncharged and nonpolar molecules do not dissolve in water – hydrophobic

8. Why is Water so Important to Life?
Thermal Properties of Water - Water moderates the effects of temperature – water does not change temperature easily
Water has high specific heat – much heat energy has to be added to get water to heat up (to break H bonds)
Ex. Bodies of water are slow to heat even when the air temperature is high

9. Why is Water so Important to Life?
Water has high heat of vaporization – much energy is needed to change liquid water to water vapor (because of H bonds) – good for cooling
Sweating to cool
Water has high heat of fusion – much energy has to be removed to get water to cool down

10. Solid water (ice) is less dense than liquid water – good for aquatic life

11. Water molecules tend to stick together
high cohesion and adhesion – water molecules tend to stick to each other (cohesion) and other substance (adhesion)
important for water transport in plants
Surface tension – outermost molecules of water form hydrogen bonds with water molecules below them – gives water high surface tension (ex. Water strider insects)