Inorganic Chemistry

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

Examples:

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

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

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

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

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

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

Solid water (ice) is less dense than liquid water – good for aquatic life http://www.pitara.com/discover/5wh/online.asp?story=25

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)