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6th HW assignment due Wednesday, March 18, by 10 pm.
Exam 2: Thursday, March 19, 7:00 pm. Sign up for conflict in 367 Noyes Lab.
1
Valence Electrons Highest or outermost energy level
electrons Where the chemistry “happens”!
Look at principal quantum level n Sulfur: 1s22s22p63s23p4
Valence electrons are in n = 3 level Valence electrons = 2 + 4 = 6
electrons
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Clicker QuestionHow many unpaired electrons does sulfur contain in its ground state? (Hint: Draw an orbital diagram.)A) 0B) 1C) 2D)3E) 6
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Clicker Question Which of the following (a-c) does not correctly match the species with the expected electron configuration?
a) A ground state calcium atom [Ar] 4s2 b) The most stable ion for bromine [Ar] 4s23d104p6 c) An excited state of sulfur [Ne] 3s23p34s1 d) At least two of the above (a-c) are incorrectly
matched. e) All of the above (a-c) are correctly matched.
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Atomic Radius (Size) Generally increases down a group
Hydrogen
INCREASES!
Francium
Orbitals are getting larger and electrons fill further and further from the nucleus at higher energy levels
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Atomic Radius (Size) Generally decreases across a row
(period) – outer electrons in the same energy levelHydrogen Fluorine
DECREASES!
More protons in each element as you move across the row. More protons will create a stronger positive force, thus attracting the electrons more strongly, pulling them in and shrinking the size.
15
Ionization Energy Generally decreases down a group
Hydrogen
DECREASES!
Francium Orbitals are getting larger and electrons fill further and
further from the nucleus at higher energy levels. Electrons are not as tightly bound by the nucleus at higher energy levels so it takes less energy to remove an outer electron.
18
Ionization Energy Generally increases across a row (period) –
outer electrons in the same energy levelHydrogen Fluorine
INCREASES!
More protons in each element as you move across the row. More protons will create a stronger positive force, thus attracting the electrons more strongly and pulling them in closer to the nucleus, requiring MORE energy to remove an outer electron.
19
Clicker QuestionRank the following from smallest to largest atomic radius.
a) Rb, Ca, Br, N b) Br, N, Rb, Ca c) N, Rb, Br, Ca d) N, Br, Ca, Rb e) Ca, Rb, N, Br
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