1. Atomic Radius Ionization Energy Electronegativity Reactivity
Periodic Trends
Atomic Radius
Ionization Energy
Electronegativity
Reactivity
½ distance between nuclei of identical atoms that are bonded
Energy required to remove one electron
Atom’s ability to add an electron.

2. Atomic Radii p.140 Period trends Trend to larger radii
because proton pull is less
on e- of same energy level …
less p+ and less e- = bigger radii
Group trends
Trend to larger atoms
because e- are added to NEXT energy level …
farther away from nucleus.
Larger
Larger
Display purple radii overhead sheet
Which has largest atomic radii? Mg, Cl, Na, P, Na
Which has largest atomic radii? Ca, Be, Ba, Sr? Ba
Which has smallest atomic radii? Li, O, C, F ? F

3. Octet rule P. 168
Chemical compounds tend to form so that each atom has an octet of electron in its highest occupied energy level. …
….atoms will try to get a group of 8 electrons in its outer orbit….
Either by gaining,
losing,
sharing ….electrons
Draw pt and number groups ….explain give and take and share .

4. Do oxidation numbers here
Ion = an atom or group of bonded atoms that have a + or – charge.
If they have lost an electron they become postive……Na+ called cation
If they have gained an electron they become negative……Cl- called anion.
Do oxidation numbers here

5. Chlorine, nitrogen, calcium, copper, sulfur, sodium,
Radii of Ions
Positive Cations lost e- ….
Lost therefore radii smaller
Negative Anion gained e- ….
gained therefore radii larger.
Describe the ion radii of the following as increase or decrease.
Chlorine, nitrogen, calcium, copper, sulfur, sodium,

6. Ionization energy p.143 energy required to remove one electron energy required to make it a cation
Period trends
Increases across period because more protons pull greater on e- in same energy level
Group trends
Increases going up group. Electrons are closer to nucleus so protons can pull electrons tighter. … therefore takes more energy to take an e-.
Measured in k/joules

7. Ionization energy= energy required to remove one electron
2nd ionization = energy required to remove a 2nd electron
3rd ionization = energy required to remove a 3rd electron.
“numbers will increase”
Turn to p.146 in book
“which would lose e- easier?”
“Arrange the following in increasing ionization energy.”
Li, O, C, K, Ne, F
K,Li,C,O,F,Ne
Which would least likely form?
Sr2+, Al3+, K2+
K2+

8. Electronegativity ability to gain electrons ability to become an anion
Period
Ability to gain electrons
increases across period
Group
Ability to gain electrons
increases going up the
Group… slightly
Which element would gain e- easier? Br, I, Cl, F F
Which element is most electronegative?
C, N, O, Se, S

9. Reactivity Which would react easier with chlorine? Sodium or Potassium
How about Sodium and Magnesium?
What would happen if you put Lithium and Potassium in a beaker?
What would happen if you then put in Bromine?