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Ch. 2 The Chemical Context of Life
Vocab and Topic Review for Ch. 2 of Cambell Biology Ninth Edition
17
Biology
Undergraduate 1
12/10/2011

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Term
Chemistry
Definition
The Study of interactions between atoms and molecules
Term
Element
Definition
All atoms of same kind
Term
Compound
Definition
Substance consisting of 2 or more elements at a fixed ratio
Term
What four elements make up 96% of mass in the Biosphere?
Definition
  • Oxygen
  • Carbon
  • Hydrogen
  • Nitrogen
Term
Proton
Definition

Atomic Charge= +1

Atomic Mass= 1 dalton (amu)

 

Term
Neutron
Definition

Atomic Charge= 0

Atomic Mass = 1 dalton (amu)

Term
Electron
Definition

Atomic Charge = -1

Atomic Mass= 0 dalton (amu)

Term
Atomic Number
Definition
  • All atoms of a single element have same number of protons in nucleus
  • Decides chemical features of element
Term
Atomic Mass
Definition
Protons+Neutrons
Term
Isotopes
Definition
Atoms with the same characteristics but different number of neutrons
Term
Half Life
Definition
Rate of decay in Radioactive Isotopes measured by how long it takes for half of the total amount to decay
Term
Carbon Dating
Definition

1 half life = 5,730 years

Measure amount of Carbon 14 in a speciman

Cannot Carbon Date specimens over 50,000 years

(Look in Book!!!)

Term
Electrons
Definition
  • Always in motion
  • Never escape- attracted to protons
  • When energy is gained, jump away from nucleus
  • valence electrons- electrons in the outermost shell
Term
Valence
Definition
  • How many bonds an atom can make
  • Periodic Table tells how many shells and valence electrons (1st period=1 shell; 2nd period=2 shells ect)
  • Octet Rule- Need 8 valence electrons to be stable

 

Term
Electronegativity
Definition

Tendency for atoms of an element to attract the shared electrons in a covalent bond

More protons=stronger pull

In a group, the pull goes down as period increases-more electron shells block to positive charge

Term
Polar Covalent Bond
Definition
Electrons are not shared equally
Term
Polar Molecule
Definition
Has to have 1 or more polar covalent bond- doesn't automatically make it polarmolecule
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