Atomic Structure WinstonSaemForsyth County Schools原子结构温斯顿salemforsyth县学校.pptVIP

Atomic Structure Chapter 4 Basic Structure of an Atom 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 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 Hyphen Notation for an Atom 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 * * Negative 0.000549 amu Electron Cloud Electrons Neutral 1.0087 amu Nucleus Neutron Positive 1.0073 amu Nucleus Proton Charge Weight Location Particle /10429/low/atomic/atomic.htm /qa/pen_number.html Red = protons Black = neutrons /physics/2000/isotopes/index.html C-12 C-13 C-14 *