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Special Topics for SOL 2 3 rd Power Point

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 2 3 rd Power Point

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  1. Special Topics for SOL 23rd Power Point Periodic Trends (Chap 14)

  2. 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

  3. You Try… • Do a shorthand configuration for • Fe • Br • Rb

  4. The Answers… • Do a shorthand configuration for • Fe = [Ar]4s23d6 • Br = [Ar]4s23d104p5 • Rb = [Kr]6s1

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Objective Chttp://www.chem1.com/acad/webtext/atoms/atpt-images/ionic_radii.jpg • 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. The End

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