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[http://www.csmate.colostate.edu/cltw/cohortpages/viney_off/atom.jpg]. Protons. Found in the nucleus. Equal the atomic number of an element. These always identify the element! + 1 Charge Atomic mass = 1 amu. [http://imagine.gsfc.nasa.gov/Images/try_this/helium.gif]. Neutrons.
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[http://www.csmate.colostate.edu/cltw/cohortpages/viney_off/atom.jpg][http://www.csmate.colostate.edu/cltw/cohortpages/viney_off/atom.jpg]
Protons • Found in the nucleus. • Equal the atomic number of an element. • These always identify the element! • + 1 Charge • Atomic mass = 1 amu [http://imagine.gsfc.nasa.gov/Images/try_this/helium.gif]
Neutrons • Found in the nucleus. • Atomic mass minus Atomic number equals # of neutrons • Atomic mass = 1 amu • No charge (neutral) [http://imagine.gsfc.nasa.gov/Images/try_this/helium.gif]
Electrons • Found in “clouds” around the nucleus • Same number as the protons when the atom is neutral! • -1 charge • Atomic Mass = 0 amu
Protons, Neutrons, & Electrons [http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/TB02_01.JPG]
Protons, Neutrons, & Electrons • Example: How many protons, neutrons, and electrons does the element Sodium have? • p+ = 11 (the atomic number) • n = 12 (mass – atomic number) • e- = 11 (neutral atoms have same numbers of protons and electrons)
Protons, Neutrons, & Electrons • Example: What about Copper? • p+ = 29 • Round the mass of 63.5 up to 64 • n = 35 • e- = 29
Isotopes Carbon - 12 Carbon - 14 • Some atoms have a different mass because they have more or less neutrons than normal. • Can be written two ways…
Isotopes of Hydrogen Normal [http://wps.prenhall.com/wps/media/objects/602/616516/Media_Assets/Chapter02/Text_Images/FG02_06-02UN.JPG]
Isotopes • Example: How many p+, n, e-, are there in Chlorine – 37? • p+ = 17 (atomic number) • n = 20 (new mass – protons!) • e- = 17 (neutral atom)
Isotopes • The atomic masses on the periodic table are averages of all the known isotopes of certain elements. 24.5% 75.5%
24.5% 75.5% 35 x 0.755 = 26.43 + 37 x 0.245 = 9.07 Periodic Table Mass = 35.5