Review of the Periodic Table and Elements
You have one class period to finish this in
1. Take a copy of the Periodic Table
Color all the metals one color
Color all the non-metals another color
Draw in the line that represents the metalloids
Color all the metalloids another color
Make a key at the top of your periodic table near the labeled box with the colors you used.
This periodic table MUST be with you at all times until the end of the year. I suggest you put it in your homework diary pocket or your science notebook. BRING IT EVERY DAY.
2. Look at the box at the top of your sheet What is the atomic number of silicon?
What is the chemical symbol for silicon?
What is the atomic mass of silicon?
What is the atomic number of carbon?
What is the chemical symbol for carbon?
What is the chemical symbol for cobalt?
What is the chemical symbol for copper?
What pattern do you see when using chemical symbols?
What is the atomic mass of chlorine?
What is the atomic mass of tungsten?
The atomic number is equal to the number of protons. The number of protons is the same as the number of electrons.
How many protons does boron have?
How many electrons does boron have?
How many protons does copper have?
How many electrons does copper have?
Which element has 13 protons?
Which element has 26 electrons?
The atomic mass is the average of the all the possible varieties of an element. These variations of the element are called ISOTOPES. These varieties are different from each other because of the number of neutrons in each atom. The average atomic mass(or sometimes atomic weight is used) is a number that considers the abundance of the that particular variety. (abundance means –how much of that particular variety is found in nature) From ChemTeam.com
Example #1: Carbon
mass number / exact weight / percent abundance12 / 12.000000 / 98.90
13 / 13.003355 / 1.10
To calculate the average atomic weight, each exact atomic weight is multiplied by its percent abundance (expressed as a decimal). Then, add the results together and round off to an appropriate number of significant figures.
This is the solution for carbon:
(12.000000) (0.9890) + (13.003355) (0.0110) = 12.011
Example #2: Nitrogen
mass number / exact weight / percent abundance14 / 14.003074 / 99.63
15 / 15.000108 / 0.37
This is the solution for nitrogen:
(14.003074) (0.9963) + (15.000108) (0.0037) = 14.007
Example #3: Chlorine / Example #4: Siliconmass number / exact weight / percent abundance / mass number / exact weight / percent abundance
35 / 34.968852 / 75.77 / 28 / 27.976927 / 92.23
37 / 36.965903 / 24.23 / 29 / 28.976495 / 4.67
30 / 29.973770 / 3.10
The answer for chlorine: 35.453 / The answer for silicon: 28.086
Show all work. Calculate the average atomic weight for:
1) magnesium
mass number / exact weight / percent abundance24 / 23.985042 / 78.99
25 / 24.985837 / 10.00
26 / 25.982593 / 11.01
Answer:
2) molybdenum
mass number / exact weight / percent abundance92 / 91.906808 / 14.84
94 / 93.905085 / 9.25
95 / 94.905840 / 15.92
96 / 95.904678 / 16.68
97 / 96.906020 / 9.55
98 / 97.905406 / 24.13
100 / 99.907477 / 9.63
Answer:
3) tin (this one is optional!! Suggestion: set it up as a spreadsheet, take it into class and impress your teacher.)
mass number / exact weight / percent abundance112 / 111.904826 / 0.97
114 / 113.902784 / 0.65
115 / 114.903348 / 0.36
116 / 115.901747 / 14.53
117 / 116.902956 / 7.68
118 / 117.901609 / 24.22
119 / 118.903310 / 8.58
120 / 119.902200 / 32.59
122 / 121.903440 / 4.63
124 / 123.905274 / 5.79
Answer:
The answers? Look on a periodic table!! Remember that the above is the method by which the average atomic weight for the element is computed. No one single atom of the element has the given atomic weight because the atomic weight of the element is an average, specifically called a "weighted" average.
For our class: Round the number to the closest whole number 31.5=32 31.4=31
The atomic mass is equal to the number of protons + the number of neutrons.
For example: Si has 14 protons, 14 electrons.
Its mass is 28.1 I round down to 28
So 28-14=14 neutrons.
Cu has 29 protons and 29 electrons. Its mass is 63.5 so I round to 64
So Cu has 64= 29 protons + ?neutrons. 64-29=35 neutrons.
How many neutrons does arsenic have?
How many neutrons does Cd have?
Atomic Mass
Atoms of the same element can have different numbers of neutrons; the different possible versions of each element are called isotopes. For example, the most common isotope of hydrogen has no neutrons at all; there's also a hydrogen isotope called deuterium, with one neutron, and another, tritium, with two neutrons.
If you want to refer to a certain isotope, you write it like this: AXZ. Here X is the chemical symbol for the element, Z is the atomic number, and A is the number of neutrons and protons combined, called the mass number. For instance, ordinary hydrogen is written 1H1, deuterium is 2H1, and tritium is 3H1.
How would you write the chemical symbol for an atom of carbon with 14 neutrons?
Research on the internet and find out why is this particular isotope of carbon so important to archeologist? CITE YOUR SOURCE.
What is a half-life?
What is the half-life for the carbon with 14 neutrons?
Electrons are in energy clouds outside of the atom.
Protons and neutrons are found in the nucleus of an atom.
We often use a Bohr model to demonstrate what an electron looks like. Remember, we can’t know exactly where an electron is, only its general location.
For the purposes of this class, we will concentrate on the first 20 elements only. You need to know the names and chemical symbols of the first 20 elements.
Electron clouds-2 electrons can fit in the first energy level
8 electrons in the second, 8 in the third, 14 in the fourth
Go to the following link
http://www.tvdsb.on.ca/saunders/courses/Online/SNC1D/McIntosh/chemistry/bohr-rutherford_diagrams.htm
Read the page
http://www.zerobio.com/drag_gr9/bohr/bohr.htm
follow the directions.
Draw a picture of the Bohr model of sodium.
Draw a picture of the Bohr model of chlorine.