How to Use Graphs to Determine Atomic Trends — Transcript

Full transcript

1. 0:00All right, let's talk about how you
2. 0:01could use a graph such as this to
3. 0:03determine a periodic trend. So, for this
4. 0:06one, you need to talk about what is the
5. 0:08trend across a period and what is trend
6. 0:10across a group. Remember, a period is
7. 0:13side-to-side across the periodic table,
8. 0:15so a period is this. A group would be up
9. 0:17and down. So, there's a group, there's
10. 0:19another group, there's another group,
11. 0:20there's another group, there's another
12. 0:22group, etc. So, uh let's start with
13. 0:25determining the trend across It doesn't
14. 0:28matter which one you do first. Maybe
15. 0:31across a group. Remember, a group is up
16. 0:33and down. So, if I want to look in a
17. 0:34group, I'm going to check lithium.
18. 0:36And looking at the periodic table, I see
19. 0:38lithium is in the same group as sodium,
20. 0:40potassium, rubidium, cesium. So, I see
21. 0:43lithium, sodium, potassium, rubidium,
22. 0:45cesium. These are in the same group as
23. 0:47lithium.
24. 0:48So, let's see what the trend is. So, in
25. 0:50this group, we see that this thing, and
26. 0:52in this case it's atomic radius, but it
27. 0:54could be anything, um this trait
28. 0:57increases from lithium to sodium. Okay,
29. 0:59notice that
30. 1:01the y-axis tells you what you are
31. 1:03looking at.
32. 1:05The x-axis
33. 1:07it says atomic number, but it says the
34. 1:08same thing, atomic number here and
35. 1:10atomic number
36. 1:12here. So, all the graphs say atomic
37. 1:14number on the y on the x-axis. It's the
38. 1:16y-axis that tells you what it is you're
39. 1:18looking at, electronegativity
40. 1:20or ionization energy or atomic radius.
41. 1:23So, in this case what we're looking at
42. 1:24is
43. 1:26atomic radius, the trait we're looking
44. 1:28at increases
45. 1:29because this is higher on the y-axis or
46. 1:31sorry, this is not as high as this one.
47. 1:34So, being that this is higher than this
48. 1:35one on the y-axis, the trait is greater
49. 1:37for this one than it is for this one.
50. 1:38So, it is increasing
51. 1:40in the direction of sodium.
52. 1:44It's further increased in the direction
53. 1:46of potassium. It's further increased in
54. 1:48the direction of rubidium.
55. 1:49So, from lithium to sodium this trait
56. 1:51increased and it increased even further
57. 1:53toward potassium, whatever. So, I look
58. 1:55on the periodic table.
59. 1:58We said it increased from lithium
60. 2:00sodium. Well, if you're going from
61. 2:02lithium to sodium, that's downward, and
62. 2:04then from sodium to potassium, it's
63. 2:05downwards. So, we're going to say this
64. 2:07trait is increasing in the downward
65. 2:09direction. So, I put an arrow like that.
66. 2:12And then um
67. 2:14for this one here,
68. 2:18now that I've looked at it across the
69. 2:19group, these are the same group as each
70. 2:21other because they're in the same
71. 2:22vertical column. Now I need to look at
72. 2:24the trend across one of these periods.
73. 2:27Remember, period is side to side.
74. 2:29So, if I do lithium again, it doesn't
75. 2:31matter. I could do any of these and get
76. 2:32the same answer. But lithium, what's in
77. 2:35the same period as lithium? So, I look
78. 2:36across the beryllium,
79. 2:38boron, carbon, nitrogen, oxygen,
80. 2:40fluorine, neon.
81. 2:42I see Oh, there's fluorine right there.
82. 2:44Fluorine is in the same group as
83. 2:45lithium.
84. 2:47Sorry, I don't know why I said group.
85. 2:48The same period as lithium.
86. 2:50So, I want to see what's in the same
87. 2:52period.
88. 2:54And these are in the same period right
89. 2:56here. So,
90. 2:58fluorine is number nine, lithium is
91. 2:59number three. So, this must be number
92. 3:00four, number five, six, seven, eight,
93. 3:02nine.
94. 3:04So, these must all be in the same period
95. 3:05as each other. And in which direction do
96. 3:06they increase? Well, fluorine is down
97. 3:09here, lithium's up here on the graph.
98. 3:10So, since fluorine's lower on the y-axis
99. 3:12than lithium is,
100. 3:14the trait is increasing as I go from
101. 3:16fluorine toward lithium
102. 3:19along this
103. 3:20period right here of these different
104. 3:22atoms.
105. 3:23So, I look on here.
106. 3:27It's increasing as I go from fluorine to
107. 3:29lithium. So, from fluorine to lithium is
108. 3:32going this way from fluorine to lithium.
109. 3:36So, the trend for
110. 3:38atomic
111. 3:39radius
112. 3:42increases as you move
113. 3:45downward
114. 3:48and toward the left
115. 3:51on the periodic table
116. 3:53as shown right here. Again, you do not
117. 3:55need to memorize this. You should be
118. 3:57able to look at this graph and come up
119. 3:58with this. So, for practice sake,
120. 4:02I'm going to go through the other two on
121. 4:03this graph, the ionization energy and
122. 4:06the
123. 4:07electronegativity. So I would say to
124. 4:09you, I'm going to go through and present
125. 4:11the answer right now. Pause this, figure
126. 4:12out for yourself
127. 4:14what the direction would be of the trend
128. 4:17as in like downward or upward or left or
129. 4:18right, and then figure it out for
130. 4:20yourself and then replay the video to
131. 4:22see what I come to and see if it's in
132. 4:23agreement. So I'll assume you're pausing
133. 4:26right now and I'll assume you're now
134. 4:27rewinding I assume now you're watching
135. 4:28now you finished solving it. So here we
136. 4:31go. Let's see.
137. 4:34What do we got here?
138. 4:35Let's do I guess I did the up and down
139. 4:37across the group first, so I'll do that
140. 4:39again. These are in the same group as
141. 4:41each other.
142. 4:43And I see that ionization energy the or
143. 4:46any trait this trait is greater for
144. 4:48helium than it is for argon.
145. 4:50So from argon toward neon toward helium
146. 4:52it's increasing as I go from argon
147. 4:54toward helium.
148. 4:57And from argon toward helium is upward
149. 5:01along the periodic table. So this trait
150. 5:02is increasing as we go upward along the
151. 5:04periodic table.
152. 5:07Let's see.
153. 5:09How about along a period? Let's see.
154. 5:13Neon helium
155. 5:15only hydrogen, so there's nothing in the
156. 5:17same period as helium here. Neon
157. 5:20yeah, all of these are in the same
158. 5:21period as neon and there's nitrogen,
159. 5:24there's beryllium, there's lithium. So
160. 5:27these things are in the same period, so
161. 5:28that's perfect. I can work with these.
162. 5:30I could also use these and get the exact
163. 5:32same answer.
164. 5:34Let's see. So from
165. 5:35this trait is increasing from lithium,
166. 5:38it's more in beryllium, it's more in
167. 5:39nitrogen, and it's most in neon.
168. 5:42So this trait is increasing as I go from
169. 5:43lithium toward neon. So from lithium
170. 5:45toward neon is
171. 5:47right
172. 5:49on the periodic table like so.
173. 5:53So from lithium toward neon by the way
174. 5:55if I looked at this from sodium it's
175. 5:56increasing toward argon.
176. 5:59So I could say from sodium it's
177. 6:00increasing as I go rightward toward
178. 6:02argon. So looking at either period I
179. 6:03would have gotten the answer. So that is
180. 6:05why I'm going to say
181. 6:07ionization energy increases as you move
182. 6:09upward
183. 6:12and toward the right.
184. 6:16Ionization
185. 6:19energy
186. 6:21Not that you need to memorize that, but
187. 6:22uh why not? It's good to have a label.
188. 6:24And then after the next one
189. 6:27do not Okay.
190. 6:30Electronegativity or any trend that has
191. 6:32a graph like this.
192. 6:34So this stuff
193. 6:36Let's see. Uh fluorine I see standing
194. 6:39out pretty obviously fluorine. Okay,
195. 6:41what's in the same group as fluorine?
196. 6:42Uh
197. 6:44chlorine is in the same group as
198. 6:46fluorine.
199. 6:47Bromine's in the same group. Iodine's
200. 6:48the same group. Astatine is the same
201. 6:50group.
202. 6:52So we can work with those.
203. 6:55So I see the trend is going generally
204. 6:57like upward. Bromine is less than
205. 7:00fluorine. So we'd say the trend's going
206. 7:02upward in this direction as I go from
207. 7:03astatine toward iodine, toward bromine,
208. 7:05toward chlorine, toward fluorine. With
209. 7:07fluorine having the most of this trait
210. 7:08cuz it's highest on the y-axis
211. 7:10and astatine having the least cuz it's
212. 7:12lowest on the y-axis. So
213. 7:15it's increasing as we go from astatine
214. 7:17toward iodine, toward bromine, all the
215. 7:19way toward fluorine. So it's increasing
216. 7:21as I go this way.
217. 7:24That's upward.
218. 7:26Okay, so from astatine to iodine, to
219. 7:27bromine, to fluorine, from bromine to
220. 7:29fluorine, whatever, from this from here
221. 7:31to here to here to here that's upward on
222. 7:32the periodic table. Oops, you can't even
223. 7:33see that. From here to here to here to
224. 7:35here that's upward on the periodic
225. 7:36table. So that's why I put this upward
226. 7:38arrow here.
227. 7:40Um the
228. 7:44period trend I can pick any of these and
229. 7:47get the exact same results. So I'll just
230. 7:48do this one just to prevent no
231. 7:49particularly good reason. Um
232. 7:52lithium, beryllium, boron, carbon,
233. 7:54nitrogen, oxygen, fluorine. Notice how
234. 7:56they're all in the same period as each
235. 7:57other. Lithium, beryllium, boron,
236. 7:59carbon, nitrogen, oxygen, fluorine. So
237. 8:03same period as each other. Lithium has
238. 8:05has least cuz it's lowest on the y-axis.
239. 8:07Fluorine has the most of this trend
240. 8:08because it's highest on the y-axis.
241. 8:11So it's increasing as they go from
242. 8:12lithium toward fluorine.
243. 8:14So it's increasing as you go from
244. 8:15lithium toward fluorine. Well, from
245. 8:17lithium toward fluorine, that is
246. 8:20rightward on the periodic table, and
247. 8:22that's the reason why I am going to put
248. 8:24a rightward-facing arrow on here because
249. 8:27the trend is increasing as I move toward
250. 8:29the right. Now, of course, in this case,
251. 8:31let's see, let's fill this in.
252. 8:33Increases you move upward
253. 8:36and toward the
254. 8:38right.
255. 8:41The trend is for
256. 8:48which I guess is inside is the power to
257. 8:49attract electrons.
258. 8:54All right, there you go. So there's some
259. 8:55pointers for how to read these graphs in
260. 8:57order to figure out what the trend is.
261. 8:59Um I would definitely say practice makes
262. 9:01perfect, so rewatch this video, try
263. 9:03again, resolve it again, and
264. 9:05um that should pretty much cover the
265. 9:08sorts of things we want you to do with
266. 9:09it. All right, so there you have it.
267. 9:10Happy studies.