Chapter 2The Chemical Context

of Life

“Hey… psst, did Mr. Slagel teach us the chemical formula for sand…..

“Are you kidding…. It is still summer, I am still on the beach

(at least in my mind).

Actually, Chemistry is THE FOUNDATION of all

BIOLOGY

Atoms

Smallest particle of elements.

Element

Matter made up of only one type of atom.

92 natural elements. Each element has a symbol.

Question?

Which Elements are necessary For Life?

Life requires about 25 chemical elements.

Macroelements

Elements needed in large amounts or quantities.

Examples:C HOPKNS CaFe Mg NaCl

Control Minus Nitrogen

Trace Elements - required by an organism in minut quantities.

ex. Fe, I, Mg

Goiter – minus Iodine

Atomic Particles

• Protons + charge, 1 Dalton mass• Neutrons no charge, 1 Dalton mass• Electrons - charge, essentially no mass

Isotopes- same # p+’sdiffering # of neutrons. - •Uses in biology as tracers

PET Scan

Electron Configuration and Chemical Properties -

•An atom’s electron configuration determines it’s chemical behavior

EnergyThe ability to do work.

Potential Energy

Is the energy that matter stores because of its position or location.

Electrons have potential energy because of their position relative to the nucleus.

Electron Orbitals

The three dimensional space where an electron is found 90% of the time.Different orbitals have different shapes.

Each orbital can hold only 2 electrons.

Chemical Bond Types

Nonpolar CovalentPolar CovalentIonicHydrogenVan der Waals

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Atoms combine by chemical bonding to form molecules -

Ionic Bond - (weak in the presence of water)

Hydrogen Bond- (weak) bonds between molecules.

A molecule’s shape determines function. Is this an emergent property?

Shape is important b/c it determines how molecules respond to one another… complementary shaped

molecules are able to bind to each other!

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