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Periodic Trends: Valence Electrons, Ion Size, Atomic Size, Electronegativity, Ionization Energy, and Reactivity

Learn about the periodic trends of valence electrons, ion size, atomic size, electronegativity, ionization energy, and reactivity. Understand how these trends affect the properties of elements.

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Periodic Trends: Valence Electrons, Ion Size, Atomic Size, Electronegativity, Ionization Energy, and Reactivity

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  1. Periodic Trends!!

  2. Valence electrons: are the s, p electrons in the highest energy level • These electrons are the ones that bond!! • The group A # matches how many valence electrons Valence electrons

  3. Valence electrons Group 13-18. # of valence electrons equal to group number - 10

  4. Octet rule: atoms will gain or lose electrons to have a full valence shell (8 electrons) You can Predict the charge of the ions

  5. Ion Size Trends • ION: an atom that has lost or gained at least one electron. • Cation: metal atom that loses e- (+) • Anion: nonmetal atom that gain e- (-)

  6. (cation is positive: metals) ALL CATS HAVE PAWS (and are mean)

  7. There are 4 trends of the periodic table you will need to know Ionic Size Atomic Size Atomic Electronegativity Ionization Energy Periodic Trends

  8. Cations are smaller than their neutral atoms • Because they lost an electron and energy level • Anions are larger than their neutral atoms • Because they gain electrons (which repulse one another) 1. Ion Size Trends

  9. Ionic Size Example • Ex 1: Which is larger? • Mg or Mg2+ • Ans: Mg • Ex 2: Which is larger? • S or S2- • Ans: S2-

  10. Fr • Atomic size increases as you move: • from right to left in a period • from top to bottom in a group • Francium has the largest size 2. Atomic size

  11. Going from Left to Right • Gets smaller because you add more protons to nucleus and then pull in the electrons • Going Down • Gets larger because you add energies Atomic Size reason

  12. Atomic Size Example • Ex. 1: Arrange the following elements in order of their decreasing size. • P(15), Mg(12), S(16) • Ans: Mg,P, S

  13. 3. Electronegativity Trends • Electronegativity is a measure of the ability of an atom to attract electrons from another atom in the compound.

  14. F Electronegativity Trends • Electronegativity increases as you move: • from left to right across a period • from bottom to top in a group • Fluorine (9) is the most electronegative element

  15. Electronegativity is opposite of atomic size, because the smaller the atom…the more electrons are attracted to the nucleus Electronegativity Reason

  16. Trends in Electronegativity Why are the noble gases not on here??!

  17. Electronegativity Example • Arrange the following in order of their increasing electronegativity. • Rb(37), I(53), Sn(50) • Ans: Rb, Sn, I

  18. 4. Ionization Energy Trends • The ionization energy is the energy needed to remove an electron from a gaseous atom. • The higher ionization energy, the harder it is to pull off electrons

  19. He Ionization Energy Trends • Ionization energy increases as you move: • from left to right across a period • from bottom to top in a group • Helium (2) has the highest ionization energy

  20. The smaller the atom, the closer electrons are to nucleus so higher the ionization energy Ionization energy

  21. Ionization Energy Example • Arrange the following in order of increasing ionization energy. • He(2), Xe(54), Ar(18) • Ans: Xe, Ar, He

  22. Periodic trends summary(add electronegativity)

  23. Fr Metal Reactivity Trends • Metal reactivity increases as you move: • right to left across a period • top to bottom in a group • Francium (87) is the most reactive metal

  24. F Non-metal Reactivity Trends • Non-metal reactivity increases as you move: • left to right across a period • bottom to top in a group • Fluorine (9) is the most reactive non-metal

  25. Reactivity Examples • Ex. 1: Which is more reactive? • Fe(26) or Co(27) • Ans: Fe • Ex. 2: Which is less reactive? • Cl(17) or F(9) • Ans: Cl

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