Lab #2Periodic Table – Part 1
Chemistry 108
Instructor:Robert Goldman
The Periodic Table
Elements
Hydrogen, Helium, Lithium, etc…– Each has its own specific symbol– First letter is capitalized, second is lowercase.
Ex: He for Helium, Li for Lithium What is the difference between Co and CO?
Elements are composed of only one type of atom! Ex: Cl2
MEMORIZE THE NAMES AND SYMBOLS FOR AT LEAST THE FIRST 32 ELEMENTS ON THE PERIODIC TABLE!
Compounds
Compounds contain more than one type of element (or atom).
CO contains Carbon AND oxygen, and is therefore a compound.
Compounds can be broken down into their elemental parts.
Subscripts and Coeffecients
2CH3OHCoeffecient Subscript
A coeffecient applies to the whole molecule is preceeds. A subscript applies ONLY to the atom (or atoms in parenthesis) it follows.
More on Subscripts and Coeffecients
4CH3(CH2)2CH3
•The coeffecient means there are 4 molecules of CH3(CH2)2CH3 present.
•CH3(CH2)2CH3 the “2” following the part in red indicates there are two CH2s present.
•How many of each element are present in the above?
More on Subscripts and Coeffecients
4CH3(CH2)2CH3
In each of the 4 molecules present, there are:
4 carbons: 4CH3(CH2)2CH3
10 hydrogens: 4CH3(CH2)2CH3
Multiply by the coeffecient of 4:
4x4=16 carbons and 10x4=40 hydrogens
Metals
Shiny in appearance. Generally good conductors of heat and
electricity. Solid at room temperature, with one exception. Monatomic (one atom)
– Ex. Al (aluminum)
Non-Metals
Not shiny in appearance. Generally not good conductors or heat or
electricity. Mostly brittle solids or gasses at room
temperature. Some are diatomic (two atoms)
– Ex. Cl2 (chlorine)
Noble Gasses
All gasses at room temperature. Located on the far right of the periodic table. Known for their stability (relatively non-
reactive).
Transition Elements
A group of elements with intermediary properties located between metals and non-metals.
These share characteristics of both groups.
Information on the Periodic Table
Atomic Subunits
•Protons (positive charge), weigh 1 amu
•Neutrons (neutral charge), weigh 1 amu
•Electrons (negative charge), 1/1800 amu
Components of an Element
The “4” is the atomic mass number and the “2” is the atomic number.
The atomic mass the the number of protons plus the number of neutrons.
He4
2
Components of an Isotope
Isotopes elements that vary only in their number of neutrons.
How many protons and neutrons are in each of the above?
Which of the above is HEAVIER?
C14
6C12
6
Ions
Formed when an element gains or loses electrons.
F + e- F-
S + 3e- S-3
Or
K K+ + e-
Ca Ca2+ + 2e-
The above are all monatomic ions.
Polyatomic Ions
Formed when a compound gains or loses electrons.
Which of these (in red) is an ion?Na+ + Cl- NaCl
or
N + O3- NO3
-
Rutherford’s Gold Foil Experiment
Rutherford’s Gold Foil Experiment
Discharge Tube
Today in lab…
Part 1
Complete Table A from items on the reagent table.
Symbol
Physical State
Color
Metallic Luster
Today in Lab
Part 2 - Pyrolysis
Obtain two test tubes, fill one 1/3 with table sugar and the other 1/3 with zinc.
Carefully heat over a Bunsen burner (using tongs) and record observations in Table B.
What would you expect for an element vs. a compound?
Today in Lab
Part 3
Examine the ball-and-stick models. Using the explanation of atom colors in your lab manual, fill in Table C with chemical formulas, etc.
Today in Lab
Part 4
Look at the discharge tube setup and manipulate the electron stream with a magnet WITHOUT TOUCHING THE APPARATUS.
Diagram the apparatus and make observations in the space provided in your lab handout.
Today in Lab
Part 5
Complete Table D by filling in the missing information for each atom given.
Don’t forget…
Hand in your lab and lab exercises before leaving today.
Have homework #2 ready to hand in at the beginning of class next week.