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Periodic Trends. Definition: Half of the distance between nuclei in covalently bonded diatomic molecule  Radius decreases across a period  Increased.

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Presentation on theme: "Periodic Trends. Definition: Half of the distance between nuclei in covalently bonded diatomic molecule  Radius decreases across a period  Increased."— Presentation transcript:

1 Periodic Trends

2 Definition: Half of the distance between nuclei in covalently bonded diatomic molecule  Radius decreases across a period  Increased effective nuclear charge due to decreased shielding  Radius increases down a group  Each row on the periodic table adds a “shell” or energy level to the atom  Radius decreases across a period  Increased effective nuclear charge due to decreased shielding  Radius increases down a group  Each row on the periodic table adds a “shell” or energy level to the atom Atomic Radius

3 Table of Atomic Radii

4 Period Trend: Atomic Radius

5  Increases for successive electrons taken from the same atom  Tends to increase across a period  Electrons in the same quantum level do not shield as effectively as electrons in inner levels  Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove  Tends to decrease down a group  Outer electrons are farther from the nucleus and easier to remove  Increases for successive electrons taken from the same atom  Tends to increase across a period  Electrons in the same quantum level do not shield as effectively as electrons in inner levels  Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove  Tends to decrease down a group  Outer electrons are farther from the nucleus and easier to remove Ionization Energy Definition: the energy required to remove an electron from an atom

6 Ionization Energy: the energy required to remove an electron from an atom  Increases for successive electrons taken from the same atom  Tends to increase across a period Electrons in the same quantum level do not shield as effectively as electrons in inner levels Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove  Tends to decrease down a group Outer electrons are farther from the nucleus

7 Table of 1st Ionization Energies

8 Periodic Trend: Ionization Energy

9  Affinity tends to increase across a period  Affinity tends to decrease as you go down in a period Electrons farther from the nucleus experience less nuclear attraction Some irregularities due to repulsive forces in the relatively small p orbitals Electron Affinity Definition - the energy change associated with the addition of an electron

10 Periodic Trend: Electron Affinity

11 Electronegativity Definition: A measure of the ability of an atom in a chemical compound to attract electrons o Electronegativity tends to increase across a period o As radius decreases, electrons get closer to the bonding atom’s nucleus o Electronegativity tends to decrease down a group or remain the same o As radius increases, electrons are farther from the bonding atom’s nucleus o Electronegativity tends to increase across a period o As radius decreases, electrons get closer to the bonding atom’s nucleus o Electronegativity tends to decrease down a group or remain the same o As radius increases, electrons are farther from the bonding atom’s nucleus

12 Periodic Table of Electronegativities

13 Periodic Trend: Electronegativity

14 Summary of Periodic Trends

15 Ionic Radii Cations  Positively charged ions formed when an atom of a metal loses one or more electrons  Smaller than the corresponding atom Anions  Negatively charged ions formed when nonmetallic atoms gain one or more electrons  Larger than the corresponding atom

16 Table of Ion Sizes


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