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Periodic Trends

Periodic Trends. Two things affecting periodic behavior of atoms Distance of electrons from nucleus Attraction between the nucleus and the electrons. Trends – Atomic Size. Atomic Size is measured by Atomic Radius Trend – L to R

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Periodic Trends

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  1. Periodic Trends Two things affecting periodic behavior of atoms • Distance of electrons from nucleus • Attraction between the nucleus and the electrons

  2. Trends – Atomic Size • Atomic Size is measured by Atomic Radius • Trend – L to R • It decreases left to right because as you move L to R the attraction for the electron increases as a result of the large nucleus thereby making the atom smaller. • Trend – T to B • It increases top to bottom because as you move T to B the number of energy levels increases thus increasing the size of the atom

  3. Trends – Ionic Size • Change in size due to the loss or gain of an electron • Cation – loss of electron – smaller than atom • Anion – gain of electron – larger than atom • Trend – L to R • It decreases left to right because as you move L to R the attraction for the electron increases as a result of the large nucleus thereby making the atom smaller. • Trend – T to B • It increases top to bottom because as you move T to B the number of energy levels increases thus increasing the size of the atom

  4. Trends – Electronegativity • Tendency of an element to attract electron when combined with another element • Trend – L to R • It increases left to right because as you move L to R the attraction for the electron increases as a result of the large nucleus so the nucleus will be more likely to attract additional electrons. • Trend – T to B • It decreases top to bottom because as you move T to B the addition of energy levels “blocks” the attraction of the nucleus for electrons (shielding) which decreases the likelihood of the element to attract electrons.

  5. Trends – Ionization Energy • Energy required to remove an electron from an atom • Trend – L to R • It increases left to right because as you move L to R the attraction for the electron increases , so more energy is required to remove an electron from an atom • Trend – T to B • It decreases top to bottom because the addition of energy levels decreases the “pull” of the nucleus on the outer electrons making it easier for them to be removed.

  6. halogens chalcogens group 14 electronegativity (across a row) f block actinoids oxygen group same column s2p5 transition metals radii across a row ionization energy (down a column) row 6 Principle Quantum # increases decreases

  7. halogens lanthanoids increases chalcogens s2 group 14 electronegativity (across a row) increases alkaline earth metals f block lanthanoids & actinoids actinoids oxygen group modern periodic table filled s & p orbitals same column similar e- configuration increasing atomic # noble gases s2p4 fluorine ionization energy (across a row) e- affinity (across a row) most reactive nonmetal increases e- configuration increases metalloids period 3 2/3 of all elements metallic & nonmetallic 1,2,or 3 valence e- 3 energy levels metals metalloids metals transition metals group 15 radii down a column liquid at room temp most reactive metal Fr increases Hg halogens 3 valence e- 4,5 or 6 valence e- varying oxidation states s2p5 group 13 nonmetals transition metals radii across a row alkali metals ionization energy (down a column) row 6 Principle Quantum # decreases loses 1 e- decreases increases 3 energy levels Mendeleev decreases

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