Chapter 2

Atoms
 The smallest component of an element
 Composed of a nucleus made of protons and neutrons
 Electrons orbit around the nucleus

Neutron
3
Proton
2
Electron
1
Carbon
12.011
4
Nucleus

Elements
 Composed of identical atoms
 Found on the Periodic Table
 EX: copper wire, aluminum foil

Elements Important to Life
Metals
Non-Metals

Symbol
6
Carbon
12.011
Atomic
Number
Element
Name
Atomic
Mass

Chemical Compounds
 Composed of 2 or more elements bonded in a fixed ratio
 Properties differ from those of individual elements
 EX: table salt (NaCl)

Types of Chemical Bonds

Three Types of Bonds

Ionic Bonds

Covalent Bonds

Hydrogen Bonds

Ionic Bonds
 One or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other.

Covalent Bonds
 One or more pairs of electrons are shared by two atoms.

Hydrogen Bonds
 the attractive force between the hydrogen attached to an electropositive atom of one molecule and an electronegative atom of a different molecule.

Biochemistry
Biology – Study of life
+ Chemistry – Study of Matter
Biochemistry – study of chemical processes in living organisms

Organic Chemistry
 study of compounds containing carbon

Organic Compounds are the basis of all life!

Isotopes

Atoms MUST contain the same number of protons! They may have different numbers of neutrons. Therefore atoms of the same element may have different masses.

Example: Carbon-14 vs. Carbon-12

Carbon-14 is important for radioactive dating.

Calculating parts if an atom:

Atomic Number = # of protons

Atomic mass = # of protons + neutrons

# of neutrons = atomic mass - # of protons

Neutral atoms: # of Protons = # of
Electrons

Elements Important to Life



Carbon, Hydrogen & Oxygen


Found in all biomolecules (carbohydrates, lipids, proteins & nucleic acids)
Carbon has 4 valence (outer) electrons. This allows carbon to bond with up to 4 other elements at one time.
Nitrogen

Found in proteins & nucleic acids
Phosphorous

Found in nucleic acids
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