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Atomic Structure. Chapter 4. Basic Structure of an Atom. http://library.thinkquest.org/10429/low/atomic/atomic.htm. Nuclear Notation for an Atom. Mass number (A) = protons + neutrons Atomic number (Z) = number of protons Number of protons = number of electrons
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Atomic Structure Chapter 4
Basic Structure of an Atom http://library.thinkquest.org/10429/low/atomic/atomic.htm
Nuclear Notation for an Atom • Mass number (A) = protons + neutrons • Atomic number (Z) = number of protons • Number of protons = number of electrons • Atomic number is the number that identifies an element!
How do I find these numbers? • Atomic number = #protons = #electrons • Mass number = #protons + #neutrons • Mass number = atomic weight rounded to nearest whole number http://education.jlab.org/qa/pen_number.html
Examples of nuclear notation Here are 3 nuclear notations for carbon. What is different about them? What is this called?
Isotopes of Hydrogen 1H 2H 3H Protium Deuterium Tritium Red = protons Black = neutrons http://www.colorado.edu/physics/2000/isotopes/index.html
Hyphen Notation for an Atom C-12 C-13 C-14 • The symbol for the element is written first. • The number after the hyphen is the mass number.
What about IONS? Neutral atom of Li Lithium ION • 3 protons (+) 3 protons (+) • 3 electrons (-) 2 electrons (-) • Charge = 0 Charge = +1 Li Li+
What about IONS (again)? Neutral atom of O Oxygen ION • 8 protons (+) 8 protons (+) • 8 electrons (-) 10 electrons(-) • Charge = 0 Charge = -2 O O-2
2 Types of Ions! • Cation – positive ion • Created when an element loses electrons • Metals • Anion – negative ion • Created when an element gains electrons • Nonmetals • Noble gases (group 18) do NOT form ions