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3:00 2:54 2:53 2:52 2:51 2:50 2:49 1:27 2:48 2:46 2:45 2:44 2:43 2:42 2:41 2:40 2:39 2:38 2:47 2:58 2:55 2:56 2:57 2:37 2:31 2:30 2:29 2:28 2:27 2:26 2:25 2:24 2:23 2:13 2:22 2:20 2:19 2:18 2:17 2:16 2:15 2:34 2:35 2:36 2:21 2:32 2:11 1:45 2:07 2:06 2:05 2:04 2:03 2:02 2:12 2:01 1:59 1:58 1:57 1:56 1:55 1:54 1:53 1:52 1:51 2:00 2:59 2:08 2:09 2:10 1:50 1:44 1:43 1:42 1:41 1:40 1:39 1:38 1:37 1:36 1:46 1:35 1:33 1:32 1:31 1:30 1:29 1:28 1:47 1:48 1:49 1:34 2:33 2:14 0:39 1:20 1:19 1:18 1:17 1:16 1:15 0:40 1:14 1:12 1:11 1:10 1:09 1:08 1:07 1:06 1:05 1:04 1:13 1:24 1:21 1:22 1:23 1:03 0:57 0:56 0:55 0:54 0:53 0:52 0:51 0:50 0:49 1:26 0:48 0:46 0:45 0:44 0:43 0:42 0:41 1:00 1:01 1:02 0:47 0:58 0:37 0:11 0:33 0:32 0:31 0:30 0:29 0:28 0:38 0:27 0:25 0:24 0:23 0:22 0:21 0:20 0:19 0:18 0:17 0:26 1:25 0:34 0:35 0:36 0:16 0:10 0:09 0:08 0:07 0:06 0:05 0:04 0:03 0:02 0:12 0:01 0:00 0:00 0:00 0:00 0:00 0:00 0:13 0:14 0:15 0:00 0:59 Do Now • Name one element that has similar chemical properties to calcium and why they are chemically similar. • Any element in the same group is chemically similar because it would have the same number of valence electrons.
Influenced by three factors 1. Energy Level • A higher energy level is further away. 2. Charge on nucleus (# protons) • More charge pulls electrons in closer. • 3. Shielding effect (a blocking effect?)
#1. Atomic Size - Group trends • As we go down a group: • each atom has another energy level, • so the atoms get bigger. H Li Na K Rb
#1. Atomic Size - Period Trends • Going from left to right across a period, the size gets smaller. • Electrons are in the same energy level. • But, there is more nuclear charge. • Outermost electrons are pulled closer. Na Mg Al Si P S Cl Ar
Rb K Period 2 Na Li Atomic Radius (pm) Kr Ar Ne H Atomic Number 3 10
#2. Trends in Ionization Energy • Ionization energy is the amount of energy required to completely remove an electron to form an ion. • Removing one electron makes a 1+ ion. • The energy required to remove only the first electron is called the first ionization energy.
Ionization Energy • The second ionization energy is the energy required to remove the second electron. • Always greater than first IE. • The third IE is the energy required to remove a third electron. • Greater than 1st or 2nd IE.
Symbol First Second Third 5247 7297 1757 2430 2352 2857 3391 3375 3963 1312 2731 520 900 800 1086 1402 1314 1681 2080 HHeLiBeBCNO F Ne 11810 14840 3569 4619 4577 5301 6045 6276
What factors determine IE • The greater the nuclear charge, the greater IE. • Greater distance from nucleus decreases IE
Shielding • The electron on the outermost energy level has to look through all the other energy levels to see the nucleus. • Second electron has same shielding, if it is in the same period
Ionization Energy - Group trends • As you go down a group, the first IE decreases because... • The electron is further away from the attraction of the nucleus • There is more shielding.
Ionization Energy - Period trends • All the atoms in the same period have the same energy level. • Same shielding. • But, increasing nuclear charge • So IE generally increases from left to right.
He • He has a greater IE than H. • Both elements have the same shielding since electrons are only in the first level • But He has a greater nuclear charge H First Ionization energy Atomic number
He • Li has lower IE than H • more shielding • further away • These outweigh the greater nuclear charge H First Ionization energy Li Atomic number
Ne He F N O C H Be First Ionization energy B Li Na Atomic number
3:00 2:54 2:53 2:52 2:51 2:50 2:49 1:27 2:48 2:46 2:45 2:44 2:43 2:42 2:41 2:40 2:39 2:38 2:47 2:58 2:55 2:56 2:57 2:37 2:31 2:30 2:29 2:28 2:27 2:26 2:25 2:24 2:23 2:13 2:22 2:20 2:19 2:18 2:17 2:16 2:15 2:34 2:35 2:36 2:21 2:32 2:11 1:45 2:07 2:06 2:05 2:04 2:03 2:02 2:12 2:01 1:59 1:58 1:57 1:56 1:55 1:54 1:53 1:52 1:51 2:00 2:59 2:08 2:09 2:10 1:50 1:44 1:43 1:42 1:41 1:40 1:39 1:38 1:37 1:36 1:46 1:35 1:33 1:32 1:31 1:30 1:29 1:28 1:47 1:48 1:49 1:34 2:33 2:14 0:39 1:20 1:19 1:18 1:17 1:16 1:15 0:40 1:14 1:12 1:11 1:10 1:09 1:08 1:07 1:06 1:05 1:04 1:13 1:24 1:21 1:22 1:23 1:03 0:57 0:56 0:55 0:54 0:53 0:52 0:51 0:50 0:49 1:26 0:48 0:46 0:45 0:44 0:43 0:42 0:41 1:00 1:01 1:02 0:47 0:58 0:37 0:11 0:33 0:32 0:31 0:30 0:29 0:28 0:38 0:27 0:25 0:24 0:23 0:22 0:21 0:20 0:19 0:18 0:17 0:26 1:25 0:34 0:35 0:36 0:16 0:10 0:09 0:08 0:07 0:06 0:05 0:04 0:03 0:02 0:12 0:01 0:00 0:00 0:00 0:00 0:00 0:00 0:13 0:14 0:15 0:00 0:59 Do Now • Which atom is larger and why: • Ca or Ba • Which atom has a higher ionization energy and why: • Na or Fr
#3. Trends in Electronegativity • Electronegativity is the tendency for an atom to attract electrons to itself when it is chemically combined with another element. • They share the electron, sometimes it’s not equal sharing. • An element with a large electronegativity pulls electrons toward itself strongly!
Electronegativity Group Trend • Down a group • Electrons are farther from the nucleus • More electrons cause shielding, • Atoms are more willing to share electrons. • Low electronegativity.
Electronegativity Period Trend • Metals • On the left of the table. • They let their electrons go easily • low electronegativity • Nonmetals • At the right end of the PT • They want more electrons. • They try to take them away from others • High electronegativity.
The arrows indicate the trend: Ionization energy and Electronegativity INCREASE in these directions