The Atom & the Periodic Table Jen Rosenthal
Review of the Atom Fill in the following table based on what you learned from last class about the atom.
History of the Periodic TableDmitri Mendeleev • Searched for way to organize elements • Put them in order of increasing masses
What you need to know http://www.classzone.com/books/earth_science/terc/content/investigations/es0501/es0501page06.cfm
Atomic Calculations # of electrons = atomic number Ex: Magnesium (Mg) has _12__ electrons # of protons = atomic number Ex: Sodium (Na) has _11_ protons # of neutrons = mass number (atomic mass rounded to nearest whole number) – atomic number Ex: Tin (Sn) has _69____ neutrons
Atomic Weight, Molecular Weight, & Formula Weight Atomic Weight- comes from the Periodic Table & is a measure of the average mass of the isotopes of the element Molecular Weight- is the mass of a molecular compound (water) Ex: H20 = 2 Hydrogen atoms = 2 x 1.01 = 2.02 1 Oxygen atom = 1 x 15.99= 15.99 Molecular Weight of water = 18.01 amu Formula Weight- is the mass of an ionic compound (salt) Ex: NaCl = 1 sodium atom = 22.99 1 chlorine atom = 35.45 Formula weight of salt = 58.44 amu
Understanding the Periodic Table Orbitals (n =2) two electrons can fit inside of one orbital Sublevels (s,p,d,f) Where s = 1, p = 3, d = 5, f = 7 Energy Levels Relates directly to # of horizontal periods in the Periodic Table (1 to 7)
Atomic Apartment Building Think of the apartments as only being able to hold two people per room & has 7 floors. Apartment Type # of rooms # of people s 1 2 p 3 6 d 5 10 f 7 14 1 1s 2 2s 1s 2p 3p 3 3s 4p 3d 4 4s 5p 4d 5s 5 6p 5d 6d 6s 6 7 7s
Sublevels Electron orbital designated as s,p,d,&f
Activity 1: Understanding Periodic Trends Instructions: Working in groups look at the following charts which show periodic trends for: • Atomic radii (atomic size) • Ionization energy (the measure of energy required to remove electrons from an atom) • Electron Affinity (the measure of attraction between incoming electrons from other atoms and the nucleus of original atom) Describe what you notice about the charts and what you think they mean. Write your thoughts in your science journal.
Activity # 2 What’s in my cereal? Materials: Special K cereal & cream of wheat, magnetic stir bar, hot plate, 750 to 1000 mL beaker Procedure: • Crush 50 g of Special K flakes with a mortar & pestle • Fill beaker with 500 mL of water • Place beaker on hot plate and add a magnetic stir bar, start the stir function • Add the crushed flakes to the water and wait 15 minutes • Remove the magnetic stir bar • Record your observations in your science journal. • What do you think is on the stir bar? Check the cereal label to think about which element you could have extracted from the cereal and explain why you think so.