The Chemical Basis Of Life
ELEMENTS AND ATOMS
Elements- substances that cannot be broken down into simpler substances by ordinary chemical reactions
--96% of the mass of most organisms: Carbon, Hydrogen, Oxygen, and Nitrogen
--Other 4%-calcium, phosphorus, potassium, sulfur, sodium, magnesium, chlorine, iron, (trace amounts
of: Iodine, manganese,
cobalt, fluorine, molybdenum, selenium, boron, silicon, etc)
Atom- defined as the smallest portion of an element that retains its chemical properties
Matter- Anything that takes up space
and has a mass.
--Atoms are comprised of : Protons(+),
Neutrons(no charge), and
--Atomic nucleus is comprised of neutron and protons.
Atomic Number- amount of proton is an atoms nucleus.
Atomic Mass- amount of proton and neutrons in an atom,
how much matter is in an atom(mass).
AMU- approximate mass of one proton or neutron
Isotopes- atoms with the same # of protons but with a different # of neutrons. Elements with different
Radioisotope- radioactive unstable isotope that emits radiation as it decays.
Orbital- 3-D space that an electron moves through. (maximum of 2)
--Electrons in orbitals with similar energy levels are said to be at the same Principle Energy Level
Valence Electrons- The outer most electrons and the most energetic (compose valence shell)
--Chemical behavior of an atom is determined by the number and arrangement of its valence electrons.
Chemical Compound- consists of atoms of two or more different elements combined in a fixed ratio.
Molecule- two or more atoms joined very strongly to form a stable particle.
describes the chemical composition of a molecule in its smallest whole number ratio
in its subscripts.
Molecular formula- subscript indicate the actual number of each type of atom in a molecule.