atomic structure
DESCRIPTION
TRANSCRIPT
Atomic Structure
Subatomic Particles
Empty Space
Subatomic Particle
Actual MassRelative
MassAtomic Mass
Units
Proton1.673 x 10-24
g1 1
Neutron1.675 x 10-24
g1 1
Electron9.11 x 10 -28
g1/1840
Approximately 0
•Atomic Mass Unit (AMU) = is defined as 1/12 the mass of a carbon – 12 atom
Atomic & Mass Number
• Atomic number:
• Mass number:
• Atomic Number = number of protons in nucleus
• Mass number = protons + neutrons
Number of electrons
• For a neutral atom:number of protons = number of electrons
• Atomic number:(# of protons)
• Number of electrons:
• Mass number:(p+ + n0)
Isotope Notation
• Atomic Number = number of protons in nucleus
• Mass number = protons + neutrons
• Number of neutrons = Mass number – atomic number
• Number of neutrons:
Examples
1. Neon – 20 – Protons:– Neutrons:– Electrons:– Atomic #:– Mass #:– Isotope Notation:
2. Iron – 56– Protons:– Neutrons:– Electrons:– Atomic #:– Mass #:– Isotope Notation:
Isotopes• Definition:
– Atoms of the SAME element, but different MASS
• What is different between these 3 atoms?
Atom OR Ion?
K
– Protons:– Neutrons:– Electrons:– Atomic #:– Mass #:
K+1
– Protons:– Neutrons:– Electrons:– Atomic #:– Mass #:
Atom OR Ion?
S
– Protons:– Neutrons:– Electrons:– Atomic #:– Mass #:
S-2
– Protons:– Neutrons:– Electrons:– Atomic #:– Mass #:
Band of Stability
Radioactive
• Low Mass– Elements 1-20
– Stable – n/p ratio = 1
– Unstable – Above or Below
• Middle Mass– Elements 21-83
– Stable – n/p ratio =• 1 to 1.5
Unstable – Above or Below
•NOTE: All atoms of elements above 83 are radioactive!!!
Radioactive
• Radioactive– Elements 84 and above
(all isotopes)– n/p ratio is too large
• Conclusions:– Number n0 = number p+ Stable– Atoms above or below this ratio Unstable– More mass Unstable (radioactive)
Radioactive
• Lithium - 8
• Number protons:• Number neutrons:
• n/p =
• Lead - 214
• Number protons:• Number neutrons:
• n/p =
Radioisotopes
• Definition:– a radioactive isotope of an element; produced
either naturally or artificially