daily question october 2, 2008
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DAILY QUESTION October 2, 2008. The rows on the periodic table are called _________. The columns on the periodic table are called__________. Agenda10/2/08. Daily Question Chapter 4 Section 2 Notes Assignments: 1. No assignment tonight. Organization of the Periodic Table (pg. 111). - PowerPoint PPT PresentationTRANSCRIPT
DAILY QUESTION
October 2, 2008
1. The rows on the periodic table are called _________.
2. The columns on the periodic table are called__________.
Agenda 10/2/08
• Daily Question
• Chapter 4 Section 2 Notes
Assignments: 1. No assignment tonight.
Organization of the Periodic Table (pg. 111)
• Groups similar elements together
• Elements are represented by their symbols
• Order is based on the number of protons (The Atomic Number of the atom)– Hydrogen has 1 proton, so it is first in the table
Periodic Law
• Order of periodic table is based on this
• States: when elements are arranged by the number of protons, similarities in their properties will occur in a regular pattern
Periods
• Horizontal rows in the periodic table
• Can determine the number of electrons based on the element’s location
Groups
• Columns in the periodic table
• Atoms of elements in the same group have the same number of valence electrons; therefore they have similar properties
Ions
• Atoms that have a net electric charge– Have either lost or gained electrons
• Cation = a positive ion (lost electrons)
• Anion = a negative ion (gained electrons)
Ions continued
• Having just 1 valence electron makes the atom highly reactive
• Having a full energy level makes the atom less reactive
Atomic Number
• Atomic # = # of protons of an atom
• In a “happy atom”, it also = # of electrons
• Each element has a different atomic number
• Atomic number never changes
Mass Number
• Mass number = # of protons + # of neutrons
• Elements can have a different mass #– Isotopes of an atom
Isotopes
• An atom with the original number of protons and electrons, but a different number of neutrons (Therefore a different mass number)– Example: Hydrogen Isotopes:
Protium, Deuterium, and Tritium
Calculating the # of Neutrons in an Atom
• # of neutrons = mass # – atomic #
Atomic Mass Unit (amu)
• Is equal to one-twelfth of the mass of a carbon-12 atom
Average Atomic Mass
• A weighted average of the isotopes, so the more commonly found isotopes have a greater effect on the average than rare isotopes