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Atomic Radii Atomic Radii Ion Size Ion Size By: Kyle Chin, Justin By: Kyle Chin, Justin Wallace, Jeff Pearson, Wallace, Jeff Pearson, and Andy Mack and Andy Mack

Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

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Page 1: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Atomic RadiiAtomic RadiiIon SizeIon Size

By: Kyle Chin, Justin Wallace, By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack Jeff Pearson, and Andy Mack

Page 2: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Definition of Atomic RadiiDefinition of Atomic Radii

-the distance from the atomic nucleus to -the distance from the atomic nucleus to the outermost stable electron shell in a the outermost stable electron shell in a neutrally charged atom neutrally charged atom

-one half the distance between nuclei of -one half the distance between nuclei of atoms of the same element that are atoms of the same element that are covalently bondedcovalently bonded

-measured in picometers (pm)-measured in picometers (pm)

Page 3: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Group Trend for AtomicGroup Trend for Atomic RadiiRadii

-As you move down a column, the atomic -As you move down a column, the atomic radius increasesradius increases

-Moving down a group, shells of electrons -Moving down a group, shells of electrons are added to the nucleus are added to the nucleus

-Each successive shell shields the more -Each successive shell shields the more distant shells from the nucleus and the distant shells from the nucleus and the valence electrons get farther away from valence electrons get farther away from the nucleusthe nucleus

-Protons are also added to the atom but the -Protons are also added to the atom but the shielding effect of the negatively charged shielding effect of the negatively charged electrons cancel out the added positive electrons cancel out the added positive charge charge

Page 4: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Period Trend for Atomic RadiiPeriod Trend for Atomic Radii

-As you move from left to right across a -As you move from left to right across a period, the atomic radius decreasesperiod, the atomic radius decreases

-Protons are added to the nucleus of atoms -Protons are added to the nucleus of atoms which strongly attract the valence which strongly attract the valence electronselectrons

- Electrons in the same shell don- Electrons in the same shell don’’t shield one t shield one another from the nucleus effectively so the another from the nucleus effectively so the shells contract, decreasing the overall size shells contract, decreasing the overall size of the atomof the atom

Page 5: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Exceptions for Atomic RadiiExceptions for Atomic Radii

-In the transition metals, the atomic radii initially -In the transition metals, the atomic radii initially decrease for the first few elements, then change decrease for the first few elements, then change very little in the middle elements, but at the end of very little in the middle elements, but at the end of the series there is a small increase in atomic radiithe series there is a small increase in atomic radii

-The small increase in atomic radii is because of the -The small increase in atomic radii is because of the d subshell is filled with electrons and thus the d subshell is filled with electrons and thus the electron-electron repulsions cause the size to electron-electron repulsions cause the size to increaseincrease

-Exceptions also exist in the lanthanide and actinide -Exceptions also exist in the lanthanide and actinide series because of how the f subshells are uniquely series because of how the f subshells are uniquely filled by electronsfilled by electrons

Page 6: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Atomic Radii TrendAtomic Radii Trend

Page 7: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Definition of Ion SizeDefinition of Ion Size

-the distance from the atomic nucleus to the -the distance from the atomic nucleus to the outermost stable electron shell in an ionoutermost stable electron shell in an ion

-Ions can either be negatively charged -Ions can either be negatively charged anions or positively charged cationsanions or positively charged cations

-measured in picometers (pm)-measured in picometers (pm)

Page 8: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

CationsCations

-Cations, positively charged atoms, have -Cations, positively charged atoms, have atomic radii that are always smaller than atomic radii that are always smaller than the neutral atom it was derived from.the neutral atom it was derived from.

-When electrons are removed from an atom, -When electrons are removed from an atom, the outer shell is lost and the electron-the outer shell is lost and the electron-electron repulsions are reduced, allowing electron repulsions are reduced, allowing all the remaining valence electrons to all the remaining valence electrons to move closer to the nucleusmove closer to the nucleus

Page 9: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

AnionsAnions

-Anions, negatively charged atoms, -Anions, negatively charged atoms, have atomic radii that are always have atomic radii that are always larger than the neutral atom it was larger than the neutral atom it was derived from.derived from.

-When an electron is added to an -When an electron is added to an atom, electron-electron repulsions atom, electron-electron repulsions increase dramatically, forcing the increase dramatically, forcing the valence electrons to move farther valence electrons to move farther apart, increasing the radii.apart, increasing the radii.

Page 10: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack

Trends for Ion SizeTrends for Ion Size

-Periodic trends in the sizes of ions are -Periodic trends in the sizes of ions are the same as the atomic radii of the same as the atomic radii of neutral atoms, they increase as you neutral atoms, they increase as you progress down a group and decrease progress down a group and decrease as you move across a period.as you move across a period.

Page 11: Atomic Radii Ion Size By: Kyle Chin, Justin Wallace, Jeff Pearson, and Andy Mack