Chemistry of Life

MatterOccupies space and has mass

MassHow much matter an object has

WeightForce of gravity pulling on an object

http://www.rgvchallengerlearningcenter.com/Space%20walk1.jpg

Elements and Atoms

Elements•Cannot be broken down into simpler kinds of matter•More than 100 exist•Fewer than 30 are important to life

Atoms and Molecules

Atom:The smallest unit of an element having all the characteristics of that element

•Electrons: negative, orbit around the nucleus, almost no mass•Protons: positive, in nucleus, mass of 1•Neutrons: neutral, in nucleus, mass of 1

http://education.jlab.org/qa/atom_model_02.gif

Atoms and Molecules

MoleculesThe smallest particle of a substance that retains the properties of the substance; composed of two or more atoms

http://www.sdsc.edu/GatherScatter/gsmar94/Images/molecule.gif

What do you remember from Junior High Science?

Atomic Number:Number of protons

Mass Number:Protons + Neutrons

Ion:+ or - charged atom

Isotope:Atoms of the same element with different numbers of neutrons (and therefore different masses)

http://serc.carleton.edu/images/introgeo/quantskills/CFourteen.gif

Bohr Model of the Atom(This model is out-of-date, but still useful for basic chemistry…)

http://js082.k12.sd.us/My_Classes/Physical_Science/atoms/atom-bohr.gif

What to remember:•Up to

•2 e- in the first shell•8 e- in the next two shells

This is what the “new” model looks like:

Ionic Bonds

When one atom donates e- to another atom.•Leads to + and - charged atoms•Attracted to each other•Overall, the molecule is neutral

Covalent Bonds

CHHHH

When atoms SHARE e- to form a neutral molecule

Methane

So how do scientists think the UNIVERSE began?

http://rhysy.plexersoft.com/Explosion%20test%202e.jpg

The formation of Earth…

•Molten gases and materials cooled•Made of atoms with different weights•Some sank; some floated to surface

http://geology.com/news/images/tungurahua-volcano.jpg

LifeLife formed on the surface from the less dense elements.

http://www.solstation.com/stars/earth2.jpg

HHydrogen OOxygen

NNitrogen CCarbon

Most common biological bonds in nature…

96% of all living matter is composed of:

H, O, N, and C

Stable or Unstable?For molecules composed of H, O, N, and/or C, just count the covalent bonds.

•Correct number? STABLE•Wrong number? UNSTABLE

O=O O=C=O-HSTABLE UNSTABLE