Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius...
-
Upload
barrie-daniels -
Category
Documents
-
view
221 -
download
0
Transcript of Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius...
![Page 1: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/1.jpg)
Trends in the periodic table
![Page 2: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/2.jpg)
Atomic radius
![Page 3: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/3.jpg)
Atomic radii trends and explanations• Atomic radius decreases across a period because
each successive element has one more proton in its nucleus and one more electron is added to the same valence shell.
• Therefore, each electron experiences a greater effective nuclear charge so is attracted more strongly to the nucleus resulting in a smaller atomic radius.
• Atomic radius increases down a group because as we progress down a group the valence electrons are found in another shell much further from the nucleus.
![Page 4: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/4.jpg)
Ionic radius
![Page 5: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/5.jpg)
Atomic vs ionic radius
• Cations: When cations form, all the valence electrons are removed from the outer shell, so the ions have one less shell than the atom. This results in a smaller radius than the atom.
• Anions: When anions form, electrons are added to the existing valence shell. Greater repulsion between valence electrons results in a larger radius than the atom.
![Page 6: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/6.jpg)
Ionic radii trends and explanations
• Ionic radius increases down a group for the same reason atomic radius increases.
• Ionic radius decreases across a period for the cations for the same reason atomic radius increases.
• However, here is a big jump in ionic radius between cations and anions because the anions have one more shell than the cations.
• The trend resumes for the anions.
![Page 7: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/7.jpg)
1st ionization energy
![Page 8: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/8.jpg)
1st ionization energy definition
• 1st ionization energy = amount of energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms (unit is kJ/mol).
• Endothermic process.• Example equation:
Na(g) Na+(g) + e-
![Page 9: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/9.jpg)
Trends and anomalies
• 1st I.E increases across period because as effective nuclear charge increases, valence electrons are held more tightly, so more energy is needed to remove an electron.
• Anomalies exist in trend due to more stable electron configurations which require more energy to remove electrons from half full or completely full subshells.
• 1st I.E increases down a group because valence electrons are found in a shell much further from the nucleus and are also shielded from the nucleus so are not held as tightly and require less energy to remove.
![Page 10: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/10.jpg)
Successive ionization energiese.g sodium
![Page 11: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/11.jpg)
Explanation of sodium successive I.E
Use the graph on the previous slide to explain the successive ionization energies for sodium. In your answer you should:• Describe what 1st, 2nd, 3rd etc ionisation energy
means.• Describe the overall trend.• Explain the jumps in I.E by referring to which
shells and sub-shells electrons are being removed from.
![Page 12: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/12.jpg)
Electronegativity
• A measure of the attraction an atom has for electrons in a bond.
• The four most electronegative elements are F, O, N and Cl.• These elements have a high attraction for electrons in a bond
because their atomic radius is relatively small and they have a high effective nuclear charge.
• Essentially F, O, N and Cl nuclei attract a pair of bonding electrons more strongly than the nuclei of other elements they are bonded to.
• Their nuclei are closer to the bonding electrons and they have a higher effective nuclear charge to attract those electrons.
![Page 13: Trends in the periodic table. Atomic radius Atomic radii trends and explanations Atomic radius decreases across a period because each successive element.](https://reader036.fdocuments.in/reader036/viewer/2022062322/5697bf931a28abf838c8fda2/html5/thumbnails/13.jpg)
Electronegativity and polarity of bonds
• The difference in electronegativity helps to determine whether a bond will be polar or not.