Special Topics for SOL 2 3 rd Power Point

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# Special Topics for SOL 2 3 rd Power Point - PowerPoint PPT Presentation

Special Topics for SOL 2 3 rd Power Point. Periodic Trends (Chap 14). Shorthand Electron Configurations. Shorthand configurations are a useful tool. Let’s look at an example for Y, Z=39 The electron configuration for yttrium is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 1

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### Special Topics for SOL 23rd Power Point

Periodic Trends (Chap 14)

Shorthand Electron Configurations
• Shorthand configurations are a useful tool.
• Let’s look at an example for Y, Z=39
• The electron configuration for yttrium is 1s22s22p63s23p64s23d104p65s24d1
• To do a shorthand configuration, we use the noble gas preceding the element and we put that in brackets(the bold and italics part)
• That’s Kr and then we also just write whatever is left over.
• [Kr] 5s24d1
You Try…
• Do a shorthand configuration for
• Fe
• Br
• Rb
• Do a shorthand configuration for
• Fe = [Ar]4s23d6
• Br = [Ar]4s23d104p5
• Rb = [Kr]6s1
Objective Bhttp://www.rsc.org/chemsoc/visualelements/PAGES/data/intro_groupvii_data.html
• Notice that the halogens all have an ending configuration of ns2np5. That means they have 7 valence electrons.
• Similarly, alkali metal have 1 valence electron. Noble gases have 8, etc. All transition metals have 2.

F [He]2s22p5Cl [Ne]3s23p5

Br [Ar]3d104s2 4p5 I [Kr]4d105s2 5p5

At [Xe]4f14 5d106s2 6p5

Objective B
• All of the transition metals have 2 valence electrons, with 2 exceptions. “d” electrons are not valence electrons. Why not?
• Transition metals are where the d orbitals are being filled up. Here are the electron configurations for all of them.

Sc [Ar]3d14s2 Ti [Ar]3d24s2

V [Ar]3d34s2 Cr [Ar]3d54s1

Mn [Ar]3d54s2 Fe [Ar]3d64s2

Co [Ar]3d74s2 Ni [Ar]3d84s2

Cu [Ar]3d104s1Zn [Ar]3d104s2

Objective B
• Notice that Cr and Cu are “exceptions.”
• They both have 1 valence electron. They do this because in the case of Cr, moving an electron from the 4s level to the 3d level gives us a half full set of d orbitals.
• That’s more stable than if Cr would have followed the pattern, and ended with “4s23d4”

Cr [Ar]3d54s1

Objective B
• Similarly, Cu has 1 electron in the 4s energy level and 10 in the 3d level, because having a full set of d electrons is also more stable.

Cu [Ar]3d104s1

Objective B
• The “inner transition metals” are the lanthanide and actinide series.
• That’s where the f electrons are filled up.
• That’s about all I’m going to say about that.
Objective C
• The periodic table allows you to predict trends in certain properties.
• Get out a periodic table and put these trends as notes on your periodic table.
• The first trend is Atomic radius.
• Atomic radius is the size of the atom. It’s defined as ½ the distance between two nuclei which are bonded together.
Objective C
• Ionic radius is another property
• It is the size of an ion. Ionic radius is fairly similar to atomic radius.
• A positive ion is also called a CATION.
• A negative ion is also called an ANION.
• A cation is always smaller than the atom it is formed from.
• An anion is always larger than the atom it is formed from.
• Since cations lose electrons to form positive ions and anions gain electrons to form negative ions, it should make sense that they are SMALLER than the atom.
Objective C
• Ionization energy is the amount of energy required to remove an electron from a gaseous atom.
• The energy required to remove the first electron is called the FIRST IONIZATION ENERGY.
• The energy required to remove the second electron is the second ionization energy. And so on…
• Metals always have LOWER ionization energies than nonmetals.
• That is because metals tend to lose electrons and nonmetals tend to gain them.
Objective C
• It is VERY MUCH easier to remove a valence electron (an electron in the highest energy level) than an “inner core” electron.
• The inner core electrons are ANY electrons which are not VALENCE electrons.

Na = 1s22s22p63s1

White = inner core electrons and Blue = Valence electrons

Objective Chttp://www.knowledgerush.com/wiki_image/8/87/LinusPauling.jpeg
• Electronegativity is measured on a scale from 0.0 to 4.0.
• By definition, F is the most electronegative element at 4.0.
• Nonmetals have a high electronegativity.
• Metals have a low electronegativity.
Electronegativity
• Think of this as the “greediness” of an atom not only holding on to it’s own electrons, but ALSO wanting to “steal” electrons from other atoms.
The Trends
• Atomic Radius AND Ionic Radius increase as you go down a group.
• Atomic Radius AND Ionic Radius decrease as you go from left to right across a period.
• Electronegativity AND Ionization Energy decrease as you go down a group.
• Electronegativity AND Ionization Energy increase as you go from left to right across a period.

Note the trends are opposites. Draw some arrows on your periodic table to help you remember the trends.