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Periodic Trends

Periodic Trends. ALL Periodic Table Trends. Influenced by three factors: 1. Energy Level Higher energy levels are further away from the nucleus. 2. Charge on nucleus (# protons) More charge pulls electrons in closer. (+ and – attract each other)

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Periodic Trends

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  1. Periodic Trends

  2. ALL Periodic Table Trends • Influenced by three factors: 1. Energy Level • Higher energy levels are further away from the nucleus. 2. Charge on nucleus (# protons) • More charge pulls electrons in closer. (+ and – attract each other) • 3. Shielding effect- Outer electrons shielded from influence of nucleus

  3. Atomic Size • Atomic radius – one half the distance between the nuclei of two atoms of the same element

  4. Leaving the noble gases out, atoms get smaller as you go across a period. Electrons are in the same energy level. But, there is more nuclear charge. The electrons are pulled closer.

  5. As we go down a group, each atom has another energy level, so the atoms get bigger.

  6. Ionization Energy • Energy required to remove an electron • IE increase from left to right across PT • The greater the nuclear charge, the greater IE, because …… • All the atoms in the same period have the same energy level. • Same shielding. • But, increasing nuclear charge

  7. IE decreases down a group because • Greater distance from nucleus decreases IE . • The electron is further away from the attraction of the nucleus, and • There is more shielding.

  8. Ionization Energies in kJ/mol

  9. Electronegativity (EN) • the ability of an atom to attract electrons when the atoms is in a compound • Metals have low EN • Non-metals have high EN

  10. Electronegativity increases from left to right across a period(Noble gases have no EN) • Because the greater nuclear charge attracts electrons.

  11. EN decreases as you go down a group. • because the farther away the electrons is from the nucleus, the more likely an atom is to lose an e- than gain an e-. • Shielding makes it more difficult to attract e-.

  12. Electron Affinity • Energy required to add an electron • Two cases: • Atom + electron  ion + energy (exothermic) • Atom + electron + energy  ion (endothermic)

  13. Ionic Radii • Ions – charged particles

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