Notes#28/Periodic Trends/Variations in Chemical Properties/AP ...

Notes#28/Periodic Trends/Variations in Chemical Properties/AP Chemistry
I. General Trends:
A . Elements in the same group or family tend to display similar properties because they have __________________________
_____________________________________.
B. DIAGONAL RELATIONSHIPS: Similarites between pairs of elements in different groups and periods of the PT
EX: the first three members of the 2nd periods (Li, Be, and B) exhibit many undeniable similarities to those
elements located diagonally below them in the 3rd period (________________________________________).
We will see examples of these similarities as we go along.
** The reason for these similarties is due to the closeness of the _____________________________________
of their cations. (charge of the cation per unit volume) Cations with similar charge densities are known to make
the same types of compounds.
II. THE REPRESENATIVE ELEMENT FAMILIES:
A. HYDROGEN:
1. Hydrogen acts like both an alkali metal and a _______________________________.
- Alkali Metal-like Comps: ______________; the hydrogen’s are _____ charged. H + is basically just a _________.
- Halogen-like Comps: _______________; the hydrogen’s are ______ charged. H - is called a ____________.
2. Reactivity: Ionic HYDRIDES react with water to produce H2 (g) and the corresponding metal hydroxides.
EX: 2 NaH (s) + 2 H2O (l) ------------->
CaH2 (s) + 2 H2O (l) --------------->
B. GROUP 1A: ALAKALI METALS (ns 1 ):
1. Have __________ ionization energies and, therefore, lose their valence e - to make _________ ions.
2. Alkali metals are soooooo reacative that they are NEVER found in their _____________________________ in nature.
They are always found as a M + ion.
3. Reactivity: REACTIVITY INCREASES AS YOU GO DOWN THE FAMILY.
- Alkali metals react vigourously with H2O to produce _______________ and the corresponding metal hydroxide.
EX: Na(s) + H2O (l) ------------->
K(s) + H2O (l) -------------->
- When exposed to air, alkali metals gradually lose their shine as they combine with O2 to form OXIDES. The type
of oxide made depends on the alkali metal.
- Lithium forms a regular oxide (O 2- ): Li(s) + O2 (g) ------------->
- Sodium forms a peroxide (O2 2- ): Na (s) + O2 (g) ------------>
- Potassium, Rubidium, Cesium form superoxides (O2 - ) M (s) + O2 (g) ------------>
(M = K, Rb, Cs)

C. GROUP 2A: ALKALINE EARTH METALS (ns 2 ):
1. Have ______ ionization energies (not quite as low as Group 1A) and therefore, lost their valence e - to make ____ ions.
2. Alkaline earth metals are not quite as reactive as the alkali metals but still are NEVER found in their ______________
____________________________state in nature.
3. Reactivity: REACTIVITY INCREASES AS YOU GO DOWN THE FAMILY.
- Alkaline earth metals (except for Be) react (not so vigorously) with water.
- Beryllium does NOT react with water. - - - - - - - - - - - - - - - - - - - -
- Magnesium reacts slowly with steam: Mg (s) + H2O (g) -------->
- Ca, Sr, and Ba react with water: M (s) + H2O (l) --------->
(M = Ca, Sr, Ba)
* As you can see, reactivity increases as you go DOWN and is less vigorous than seen in the alkali metals.
- Alkaline earth metals react with O2(g) to form regualar OXIDES (O 2- ).
- Be and Mg only form oxides at elevated temperatures: Be (s) + O2(g) ---------->
- CaO, SrO, and BaO all form at ______________ temperature.
Mg (s) + O2 (g) ----------->
D. GROUP 3A - BORON FAMILY (ns 2 np 1 ):
1. Boron is a _______________________. The other members of the family (Al, Ga, In, Tl) are _________________.
2. Boron makes mostly molecular compounds (does not make ionic compounds) and does not react with ____________
or ____________________________.
3. Aluminium ONLY makes a ____________ ion.
Aluminum reacts with O2(g) to make Aluminum Oxide. Al (s) + O2(g) ----------->
4. The rest of the family, Ga, In and Tl, make _________ ions, like Al, as well as _________ ions.
As you go down the family, the +1 ion becomes increasingly more stable.
E. GROUP 4A - CARBON FAMILY (ns 2 np 2 ):
1. This family includes nonmetals, semimetals, and metals. Carbon is a __________________, Silicon and Germanium
are ________________________, Tin and lead are ________________________.
2. C, Si, Ge do NOT form ionic compounds.
3. Sn and Pb are not “metallic” enough to react with water, they do react with acids, however, to liberate H2(g).
Sn (s) + HCl (aq) ---------> NET IONIC: Sn (s) + H + (aq) ------>
4. Group 4A elements form compounds in both the +2 and +4 oxidation states. As you go down the table, the +2 ox.
state becomes more stable.
EX: CO2 is _____________ stable than CO SiO2 is __________ stable than SiO
P 4+ is _____________ stable than P 2+
F. GROUP 5A - NITROGEN FAMILY (ns 2 np 3 ):
1. Nitrogen and Phosphorus are ______________________________, Arsenic and Antimony are _________________,
Bismuth is a ________________________.