Name
APS
Date
Mrs. Jiménez
Partners:
Lab Activity: Periodic Trends – Atomic Radius
Some properties of elements show repeating patterns on the periodic table.
This is called periodicity.
One of these properties is atomic radius. Atomic radius is the distance from
the nucleus of an atom to its outermost electron/orbital.
Procedure:
1. For the following data, plot the atomic number on the x-axis and atomic
radius on the y-axis. Plot each period in a different color. When
connecting the dots, use a plain pencil to connect the dots between
periods, but colored pencil to connect the dots WITHIN periods.
2. Follow all graphing rules! Pull these up on your Ipad from the class
website and follow each one. This is a graphing review lab!
3. Make a key (in a box) to show the different periods (1 -4).
4. Using your graph, predict an atomic radius for N, Al, and Sc. Fill these
predictions into Table #2 below. Show your “work” for this by drawing a
dotted pencil line from your graph to the y axis to indicate your
extrapolated data.
Table 1 – Elemental Data
Element
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Atomic
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
Atomic
Radius (pm)
32
37
130.
99
84
75
?
64
60
62
160.
140.
?
Si
P
S
Cl
Ar
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
114
109
104
100.
101
200.
174
?
148
144
130
129
124
118
117
122
120
123
120.
120.
118
117
116
5. Use your I-pads to find the “NY State Reference Tables, Table S” and look
up the true atomic radius of N, Al, and Sc. Fill these values in on Table
#2 also in the third column for “accepted atomic radius.”
Table 2 – Predicting Atomic Radius
Element
Predicted Atomic
Radius
Accepted Atomic
Radius
Percent Error
N
Al
Sc
6. Perform three percent error calculations using this equation:
Accepted value – Experimental value x 100 = percent error
Accepted value
Where the accepted value = the one you looked up and the
experimental value is the one you predicted using the graph.
Show these calculations in the correct 3 step method with units
and sig figs below! Then fill in your final percent error values in
Table #2 above.
Calculations
7. If time allows, try to create a replicate graph on your ipad by going to
google account and then google spreadsheets. It works a LOT like MS
Excel. Be sure that even though this is a computer based graph, that it
also includes axes labels, units, overall title, key, etc. just like a
handmade graph would. You will have to either first type in all the data!!
We will do more on this after Christmas
Analysis Questions and Extra Research
1. What is atomic radius?
2. Look at your graph and explain what trend you see in atomic radius as
you go down a group of elements.
2b. Using your Ipad to research, clearly explain WHY you see the trend in
#2 above.
3. Look at your graph and explain what trend you see in atomic radius as
you go across a period.
3b. Using your Ipad to research, clearly explain WHY you see the trend in
#3 above. (This one is a bit tricky! Explain it well for full credit and don’t
copy and paste!)
References (Properly list all references used to determine your answers above.
APA format must be used. No In-text citations are required.)