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© Copyright Pearson Prentice Hall
Slide 1 of 31
Periodic Trends > Types of Periodic Trends
5 Periodic Trends
1.Atomic Radii (AR)
2.Ionization Energy (IE)
3.Electronegativity (EN)
4.Ionic Radii (IR)
5.Metallic Charateristic (MC)
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Slide 2 of 31
Periodic Trends > Columbic Force
Columbic Force (CF) (explanation for Periodic Trends)
Opposite Charged Particles – Attract
Same Charged Particles – Repel
F = (Q1*Q2)/r
Q1 – charge on particle 1 (nucleus “+” charge)
Q2 – charge on particle 2 (valence e, “-” charge)
r – distance between particles
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Slide 3 of 31
Periodic Trends > Columbic Force – Periodic Trend
Periodic Trend for Columbic Force (CF)
Down a Group:
Trend:
Reason:
Across a Period:
Trend:
Reason:
Slide 4 of 31
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Periodic Trends > Trends in Atomic Size
The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined.
6.3
Slide 7 of 31
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Periodic Trends > Atomic Radii (AR) Periodic Trend
Periodic Trend for Atomic Radii (AR)
Down a Group:
Trend:
Reason:
Across a Period:
Trend:
Reason:
Slide 8 of 31
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Periodic Trends > Trends in Ionization Energy
Ionization Energy (IE) - The energy required to remove the first valence electron from an atom (atom is in the gas phase).
• What is holding the valence electron to the atom?
• Valence electron tightly held or loosely?
6.3
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Slide 12 of 31
Periodic Trends > Ionization Energy (IE) Periodic Trend
Periodic Trend for Ionization Energy (IE)
Down a Group:
Trend:
Reason:
Across a Period:
Trend:
Reason:
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Slide 13 of 31
Periodic Trends > Ionization Energy (IE) Periodic Trends
Two Exception to 1st Ionization Energy (IE) (Across the Period):
1. Be B
Trend:
Reason:
2. N O
Trend:
Reason:
Slide 14 of 31
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Periodic Trends > Trends in Electronegativity
•Trends in Electronegativity
Electronegativity is the ability of an atom, in a chemical bond, to attract the shared valence electrons to itself. (i.e. the shared valence electrons are physically closer to the higher EN value atom than the other atom in the chemical bond).
• What EN really means?
•Fluorine?
6.3
Slide 15 of 31
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Periodic Trends > Trends in Electronegativity
Representative Elements in Groups 1A through 7A
6.3
Slide 16 of 31
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Periodic Trends > Electronegativity (EN) Periodic Trend
Periodic Trend for Electronegativity (EN)
Down a Group:
Trend:
Reason:
Across a Period:
Trend:
Reason:
Slide 17 of 31
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Periodic Trends > Ions
An ion is an atom or group of atoms that has a positive or negative charge.
• A cation is an ion with a positive charge.
• An anion is an ion with a negative charge.
6.3
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Slide 18 of 31
Periodic Trends > Ions
Metals elements lose valence electrons to form cation ions. Cation radii (IR) are always smaller than atomic radii (AR) [i.e. IR < AR]
6.3
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Slide 19 of 31
Periodic Trends > Ions
Non-metal elements gain valence electrons to form anion ions. Anion radii (IR) are always larger than atomic radii (AR) [i.e. IR > AR]
6.3
Slide 20 of 31
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Periodic Trends > Trends in Ionic Size
Relative Sizes of Some Atoms and Ions
6.3
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Slide 21 of 31
Periodic Trends > Trends in Ionic Size
Trends in Ionic Size
6.3S
ize
ge
ner
ally
incr
ease
s
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Slide 22 of 31
Periodic Trends > Ionic Radii Periodic Trend
Periodic Trend for Ionic Radii (IR)
Down a Group:
Trend:
Reason:
Across a Period: Metals large small, then Non-metal large small (Caution: Are not looking at same charge ion when across period)
Metals: IR vs. AR :
Reason:
Non-metals: IR vs. AR :
Reason:
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Slide 23 of 31
Periodic Trends > Metallic Characteristics Periodic Trend
Definition of Metals
Composed of cations in a “sea” of free flowing valence electrons.
• Properties – Good Electrical Conductor
• Properties – Good Heat Conductor
• Properties – Malleable & Ductile
• Periodic Trends (Metallic Characterstic)