1. Periodicity

2. Periodic Table [74-75]
Elements in the periodic table are arranged according to increasing atomic number
Elements in a group have the same number of valence electrons
Elements in a given group have similar physical and chemical properties
Elements in a period have valence electrons in the same energy level

3. Periodic Table [74-75] Do you remember where the:
Alkali metals are located
Halogens are located
Alkaline earth metals are located
Noble gases are located
Transition metals are located
Blocks that correspond to the s, p, d, and f sublevels are located
Exercises 1-3 page 75

4. Periodic Trends Nuclear charge (NC) Electron shielding (ES)
Atomic radius (AR)
Ionic radius (IR)
Ionization energy (IE)
Electronegativity (EN)
Melting point(MP)
Reactivity (R)
Moving to topic 4

5. Effective Nuclear Charge [76]
Nuclear charge = given by atomic number
Effective nuclear charge = net positive charge experienced by an electron in a many-electron atom; this charge is not the full nuclear charge due to shielding of the nucleus by the other electrons
Electron shielding = electrons are repelled by inner electrons, thus shielding them from the full nuclear charge

6. Electron shielding[76]

7. Effective Nuclear Charge/ Electron Shielding [76]

8. Periodic Trends

9. Periodic Trends

10. Atomic Radius [77]
atomic radius is usually defined as half the distance between the nuclei of two bonded atoms of the same element.
noble gases
do not fit trend

11. Atomic Radius [77]
Explanation of trend
Exercise 4 page 77

12. Ionic Radius [77-78] Cations are smaller than parent atoms
Anions are larger than parent atom
Cation radii decrease groups 1 to 4
Ionic radii increase between cation and anion
Anion radii decrease group 4 to 7
Ionic radii increase moving down group

13. Ionic Radius [77-78]

14. Ionic Radius [77-78] Explanation of trend
Exercises 7, 8 and 9 pages 80-81

15. Ionic Radius [77-78]
Isoelectronic = atoms or ions with the same number of electrons
Ne, F-, O-2, N-3, Na+, Mg+2, Al+3 all contain 10 electrons
In an isoelectronic series, the species with the highest number of protons has the smallest radius.

16. Ionic Radius [77-78]
Explanation of trend

17. Periodic Trends – Ionization Energy and Electronegativity [78-79]
Ionization energy is the energy required to removed the outermost electron from an atom in the gaseous state.
Electronegativity is the ability of an atom in a chemical bond to attract electrons to itself
Both trends deal with the attraction to electrons

18. Periodic Trends – Ionization Energy and Electronegativity [78-79]
Explanation of trends

19. Chemical reactivity [81-85]
Noble gases are chemically inert
Stable octet; complete shell of electrons
Other elements react to gain or lose electrons in order to achieve octet: stable; low energy

20. Chemical reactivity [81-85]
Reactivity trend of alkali metals

21. Chemical reactivity [81-85]
Reactivity trend of halogens

22. Trends of Period 3 [86-88] Na Mg Al Si P S Cl Metal Metalloid Nonmetal
(shiny, soft, ductile, malleable, conducts electricity solid or molten)
Metalloid
Nonmetal
(dull, brittle, nonconductor)
Na2O
MgO
Al2O3
SiO2
P4O10
P4O6
SO2
SO3
Cl2O7
Cl2O
Ionic
(Water soluble, conductor in aqueous or molten, high MP,)
Giant covalent
(not water soluble, HIGH MP)
Molecular
(note water soluble, nonconductor, low MP)
Basic oxide
amphoteric
Acidic oxide ?? ??

23. Period 3 oxides + water [87-88]
Na2O + H2O →
MgO H2O →
Al2O H2O →
SiO H2O →
P4O H2O →
P4O H2O →
SO H2O →
SO H2O →
Cl2O H2O →
Cl2O H2O →

24. Exercises page 88