Atomic Size (radius) Ionization Energy Electronegativity Periodic Trends Atomic Size (radius) Ionization Energy Electronegativity Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

What’s the key idea? Remember: It’s all about the pull! How much attraction is there between the protons and the electrons? How much “inward pull” do the protons have on the electrons in the outer shell? Remember, those electrons are called _________________________ electrons. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Atomic Size One way to think about atomic size is to look at the units that form when atoms of the same element are joined to one another. These units are called molecules. Because the atoms in each molecule shown below are identical, the distance between the _________ of these atoms can be used to estimate the size of the atoms. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

This size is expressed as an atomic radius. Trends in Atomic Size This size is expressed as an atomic radius. The atomic radius is ______________ of the distance between the nuclei of two atoms of the same element when the atoms are joined. Often measured in picometers (pm) One trillion picometers = one meter Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

______________ from top to bottom within a group Trends in Atomic Size In general, atomic size… ______________ from top to bottom within a group ______________ from left to right across a period Remember, protons pull electrons toward the center of the atom. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Why does atomic size _____________ down a group? Trends in Atomic Size Why does atomic size _____________ down a group? More protons (more “nuclear charge”) means _______________ inward pull on the electrons HOWEVER… There are more occupied energy levels (more “shells” of electrons) So the valence electrons are “___________” by the inner electrons and aren’t pulled in as much The “shielding effect” is _______________ than the increase in nuclear charge So atomic size ___________________ Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Why does atomic size _____________ across a period? Trends in Atomic Size Why does atomic size _____________ across a period? More protons (more “nuclear charge”) means _____ inward pull on the electrons Electrons are also being added, but they are being added to the _________ energy level so there is no additional “shielding” So atomic size ________________ Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Atomic Size The figure below summarizes the group and period trends in atomic size. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Ionization Energy Electrons can move to higher energy levels when atoms __________ energy. Sometimes the electron has enough energy to overcome the attraction of the _________ in the nucleus. The energy required to remove an electron from an atom is called ionization energy. The energy required to remove the first electron from an atom is called the first ionization energy. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Ionization Energy In general, ionization energy… ______________ from top to bottom within a group ______________ from left to right across a period Remember, protons pull electrons toward the center of the atom. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Ionization Energy Why does ionization energy _________ down a group? As you move down the group, _________ are being added to the next energy level These outer electrons are more “______________” by the inner electrons They have _____________ attraction to the protons in the nucleus ___________________ to remove Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Ionization Energy Why does ionization energy _________ across a period? More ________________ are being added Greater ________________ charge Protons have _____ inward pull on electrons ___________________ to remove Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Ionization Energy The figure below summarizes the group and period trends for the first ionization energy. Energy generally increases Energy generally decreases Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Electronegativity There is a property that can be used to predict the type of bond that will form during a reaction. This property is called electronegativity. Electronegativity is the ability of an atom of an element to attract ___________________ when the atom is in a compound. Usually expressed in “Pauling units” We don’t have electronegativity values for the noble gases because they have a full valence shell (they are “happy”)  they don’t form many compounds Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Electronegativity In general, electronegativity… ______________ from top to bottom within a group ______________ from left to right across a period Remember, protons pull electrons toward the center of the atom. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Electronegativity Why does electronegativity _________ down a group? As you move down the group, electrons are being added to the _____ energy level The protons in the nucleus are “____________” by multiple energy levels __________ pull Less ability to attract additional _________ Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

Trends in Electronegativity Why does electronegativity _________ across a period? More ______________ are being added Greater _______________ charge More ___________ ____________ ability to attract electrons Draw the NaCl example below: Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .

This figure summarizes several trends that exist among the elements. OVERALL This figure summarizes several trends that exist among the elements. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. .