Review Atomic Number (Mass Number)= Number of Protons Atomic Mass= Number of Protons + Number of Neutrons
Quick Questions (5 minutes) Proton= 1 amuNeutron= 1 amu 1.What is the atomic mass if you have 4 protons and 3 neutrons? 2.What is the atomic mass if you have 6 protons and 4 neutrons? 3.How many neutrons do you have if you have an atomic mass of 12 amu and have 7 protons? 4.How many neutrons do you have if you have an atomic mass of 35 amu and have 18 protons? 5.How many protons do you have and what symbol is the element if you have an atomic mass of 36 and have 19 neutrons?
Peanutium Lab A new element has been discovered called “Peanutium” after its uncanny resemblance to the packing peanuts used for shipping packages. There is not much known about this element. You are one of the first groups to examine Peanutium and it is hoped that you will be able to uncover some of its mysteries. You are assigned the task of determining the atomic mass of this element and the number of atoms of this element you are working with.
Determining Atomic Mass 1)Place 10 “Peanutium” atoms on the electronic balance and record the mass. 2)Divide the mass from step 1 by 10 to find the average atomic mass. 3)The average atomic mass is the same as the molar mass
Determining the Number of Atoms 1)Use the electronic balance to determine the mass of the entire bag of “Peanutium” atoms 2)Subtract 11.86 g from the mass from step 1. This is the mass of the bag. 3)Divide the mass of step 2 by the atomic mass from the previous experiment to find the number of atoms present in the bag.
Imagine you received a bag full of three kinds of M&Ms. You emptied them out and counted them all. You had 25 peanut, 60 regular, and 40 pretzel. Using this information and the table below, calculate: relative abundance (the percentage of each total) for each M&M and the relative mass (The percentage x the average mass) of M&Ms if all three types are isotopes. To which type of M&M was the relative mass closest to? Why might that be? M&MAverage Mass Regular0.45 g Pretzel0.35 g Peanut0.55 g
Now for the Math RELATIVE ABUNDANCE Peanut= (25/(25+60+40))=0.20 20% Regular= (60/125)= 0.48 48% Pretzel= (40/125)= 0.32 32% RELATIVE MASS Peanut= (0.55g)(0.20)= 0.11g Regular= (0.45g)(0.48)= 0.216g Pretzel= (0.35g)(0.32)= 0.112g 0.438 g RELATIVE MASS= 0.11g+ 0.216g+ 0.112g= 0.438 g Closest to the Regular M&M due to the amount of Regular M&M’s
Activity: Mystery Pennies Tomorrow, you will get a “mystery” pack of 10 pennies from your teacher. Your objective is to answer the question: How many pre-1982 and how many post-1982 pennies are in your sample? Task Today: Write and carry out a procedure to answer the question from the objective. – Procedure must include methods of collecting numerical data and a data table – You must check with the teacher before beginning any work – YOU CAN NOT OPEN THE MYSTERY CONTAINER!
012345678 10X 9X 8X 7X 6X 5X 4X 3X 2X 1 Post 1982 Pennies Pre-1982 Pennies You will calculate the abundance mass for each of the X spots given 910 X 0X