Bell Work• Write the Electron Configuration for

Potassium:

1s 2s 2p 3s 3p 4s 3d

Argon:

1s 2s 2p 3s 3p 4s 3d

• Then Circle the Valence Electrons

Periodic TrendsPeriodic Trends

Ionization EnergyIonization EnergyAtomic RadiusAtomic Radius

Electron AffinityElectron AffinityElectronegativityElectronegativity

Objectives:Objectives:• Compare period and group

trends.

• Relate period and group trends in atomic radii to electron configuration

BackgroundBackground• Electrons can jump between shells/orbitals

• The electrons can be pushed so far that they escape the attraction of the nucleus

• Losing an electron is called ionization

• An ion is an atom that has either a net positive or net negative charge

• Gaining an electron is electron affinity

What are Periodic Trends?What are Periodic Trends?• Trends among elements in the

periodic table. Example:

Atomic Radius(size)Ionization EnergyElectronegativityElectron Affinity

What is Atomic Radius?What is Atomic Radius?

• Half the distance between adjacent nuclei

• Decrease in atomic radius as you move left to right on the periodic table:

Valence electrons are pulled closer to the nucleus

• Increase in atomic radius as you go down a group on the periodic table:Radius increases because shells are added

because of more electrons

What are the atomic radius trends?What are the atomic radius trends?

Which Atom has the bigger atomic radius?Which Atom has the bigger atomic radius?

• Carbon or Fluorine

• Answer: Carbon

• Carbon or Tin

• Answer: Tin

What is Ionization energy?What is Ionization energy?

• Ionization energy is the energy required to remove one outer electron from an atom

11p+ 12n°

11p+ 12n°

Loses an electron

Na Atom Na Ion

• Increases a you move from left to right. More protons means greater attraction between nucleus and outer electron thus higher ionization energy.

Li ( 1)

+++

Be ( 2)

++++

B ( 3)

+++++

What are the periodic trends for What are the periodic trends for Ionization Energy? Ionization Energy?

• Decreases a you move down a group. Radius increases because shells are added.

• Increased radius will make it easier to lose an electron because of greater distance between positive and negative charges

What are the periodic trends for What are the periodic trends for Ionization Energy? (Continued) Ionization Energy? (Continued)

Which Atom has the greater Ionization Which Atom has the greater Ionization Energy?Energy?

• Boron or Aluminum

• Answer: Boron

• Sodium or Magnesium

• Answer: Magnesium

• Electron affinity is energy associated with an atom gaining an electron.

• Electronegativity is a number that describes the relative ability of an atom to attract electrons.

What is Electronegativity… Electron What is Electronegativity… Electron Affinity?Affinity?

• It is highest in the top right where atoms are smallest with the greatest number of protons (Electron Affinity)

• The trend is the same as affinity for the same reason (Electonegativity)

What are the trends for What are the trends for Electronegativity… Electron Electronegativity… Electron Affinity?Affinity?

Electronegativity

Which Atom has the greatest Which Atom has the greatest Electronegativity? Electronegativity?

Fluorine

Homework

• Periodic Trends

• Engrade.com

Classwork• Graphing Periodic Trends(periods 1, 2, 3)

• Connect the points of elements in each period, so that there are 3 separate curves (use 3 different colors on the graphs).

• Atomic Radius: Y- Axis

• Atomic Number: X-Axis

Thought For the Week!

• Does thou love life….Do not squander time, because that is the stuff life is made of.

Benjamin Franklin