1. Periodic Table and Trends

2. I. CHEMICAL PERIODICITY
"the variation in properties of elements based on their positions in the periodic table”

3. Dmitri Mendeleev
a 19th cent. Russian chemist, published (1862) an arrangement of elements based on chem. properties of the elements, so that elements with similar properties fell in the same column (62 known in his time)
Brilliant b/c: he left spaces in columns for yet-undiscovered elements

4. Lothar Meyer
a 19th century German chemist, published an arrangement of elements based on physical properties of elements
the two tables were surprisingly similar, and emphasized regular periodic repetition of properties of elements with increasing a.w.

5. Periodic Law
a revision of Mendeleev's/Meyer's groupings, states that "the properties of the elements are periodic functions of their atomic NUMBERS" (not their atomic weights!)

6. 1. Groups/Families vertical columns -
elements in a group/family have similar chem/phys prop's
e- dot notation is the same in a group

7. 1. Groups/Families

8. 2. Periods/Rows horizontal rows -
elements in a period have properties that change progressively across the periodic table

9. 2. Periods/Rows

10. 3. Group Numbers -1-8 or 1-18 or A & B
-makes sense to number them 1-8 (based on e- dots) when speaking in general
-When getting specific, “column 17” would obviously mean the Halogens

11. 4. Period Numbers
1-7 (correspond to "n", or principal quantum number), which gives an idea of distance from the nucleus 1 2 3 4 5 6 7

12. METALS 5. Major Categories Metalloids Inert (Noble) Gases Non-Metals
Transition Metals
Transition Metals
Metalloids
Lanthanides
Actinides
Actinides

13. 6. Group Names
a. Alkali Metals - Grp 1 - b/c they are metals that can react w/ water, forming alkaline sol'ns. Found combined in nature; not uncombined.
b. Alkaline Earth Metals - Grp 2 - Found uncombined in nature
c. Halogens - Grp 7 - "salt-formers"
d. Noble (Inert) Gases - Grp 8 - Tend to be unreactive due to their completed octet of e-'s

14. 6. Group Names Alkali Metals Chalcogens Alkaline Earth Metals Halogens
Noble Gases
(Inert
Gases)

15. Important Trends First Ionization Energy Second Ionization Energy
Electron Affinity
Atomic Radii
Ionic Radii
Electronegativity

16. First Ionization Energy
Def: “the min. am’t of energy required to remove the most loosely held e-”
top to bottom: decreases, since as atomic size increases, e- from higher energy levels are "shielded*" from the nucleus and are therefore not as tightly bound. (the "*shielding effect")
left to right: increases, as elem's closer to group 7 tend to want to gain e-'s. (Noble gases have the highest F.I.E.)

17. F.I.E. Which of these more easily loses e-’s?
That’s the one with lower F.I.E.

18. First Ionization Energy

19. Second Ionization Energy
Def: “the amount of energy required to remove the second e-
Which is higher – FIE or SIE?
top to bottom and left to right - same trend as F.I.E.
S.I.E.

20. Second Ionization Energy

21. Electron Affinity
Def: the amount of energy absorbed when an e- is added to an isolated gaseous atom forming a -1 ion
Elements w/very neg. E.A.'s gain e-'s easily to form anions.
top to bottom - values become less negative
left to right - values become more negative

22. Electron Affinity

23. Ionic Radii Defined as radius of the ion
top to bottom - increase, due to the increase in "n"
left to right - decrease, due to the addition of e- to same "n“
Explanation: e- are added to same “n”; there is a ‘tightening” of the overall atomic radius due to increased positive nuclear charge

24. For Metal Atoms forming Metal Ions…
Ionic radii smaller since e- is lost from outermost level;
ie: Na

25. For Nonmetal Atoms forming Nonmetal Ions
As an e- is added to a valence shell, more room is needed (like charges repel) and the ion is larger
ie: F

26. Electronegativity
Def: a measure of the relative tendency of an atom to attract e-'s to itself when it is chemically combined with another atom
Developed by Linus Pauling
EN has no units, since it's relative
top to bottom - decrease in EN
left to right - increase in EN

27. Using Electronegativity to Determine Bond Type
there are two main types of chemical bonds,
a) ionic - have a diff. in EN of > 1.67
b) covalent - have a diff. in EN of < 1.67
COVALENT < 1.67 < IONIC

28. Calculate the Bond Type
i.e.: What kind of bond is likely to form in:
H2O
CO2
NaBr
MgO
For: H – O you would look up the EN’s for H and O and subtract
For: C – O you would look up the EN’s for C and O and subtract
For: Na – Br (same process)
More on this in the next unit!
For: Mg – O (same process)

29. Miscellaneous Terms anion - any negative ion cation – any positive ion
isoelectronic –
(ie: N-3, O-2, F-1, Ne, Na+1, Mg+2, Al+3 ) What must this mean?
For the next unit…
Polyatomic ion – a group of atoms that behaves as a single ion (ie: NH4+, NO3-, CO3-2, SO4-2, etc etc)