Periodic Properties: Groups 5A, 6A, and 7AA. Group 5A

1. Elements and Symbols Element Type State

a. N = Nitrogen Non-metaldiatomic gas

b. P = Phosphorous Non-metal solid

c. As = Arsenic Metalloid solid

d. Sb = Antimony Metalloid solid

e. Bi = Bismuth Metal solid

2. Some chemistry of the non-metal Group 5A Elements

a. The elements tend to react to gain 3 electrons to be like noble gas

b. These elements react with oxygen to form acidic compounds

- HNO3 = Nitric Acid H3PO4 = Phosphoric Acid

- P4(s) + 5 O2(g) -----> P4O10(s)

- P4O10(s) + 6 H2O -----> 4 H3PO4(aq)

c. Important Biological Elements

- N is a component of every amino acid (protein) and DNA

- P is a component of DNA

d. Phosphorous has more than one allotrope

- Allotrope = stable solid phase

- P4(s) is called “white phosphorous” is tetrahedral, and burns in air

- Pred is called “red phosphorous” and is made of chains of P4 tetrahedra

- Pblack is called “black phosphorous” and is a crystalline solid

e. We will be reacting Red Phosphorous with Oxygen today in lab

- Don’t bother with the bottle

- Burn the phosphorous in the bunsen burner in the hood

- Have a distilled water dampened piece of pH paper ready

- Put the pH paper (green when damp) in the phosphorous smoke

- If it turns red, that indicates the formation of acid

- DON’T PUT HOT COMBUSTION SPOON INTO BOTTLE!!!

B. Group 6A

1. Elements and Symbols Element Type State

a. O = Oxygen Non-metal diatomicgas

b. S = Sulfur Non-metal solid

c. Se = Selenium Non-metal solid

d. Te = Tellurium Metalloid solid

e. Po = Polonium Metalloid solid

2. Some chemistry of the non-metal Group 5A Elements

a. The elements tend to react to gain 2 electrons to be like noble gas

b. 20% of the atmosphere and 50% of the crust is O (by mass)

c. These elements react with oxygen to form acidic compounds

d. Sulfuric Acid (H2SO4) is the largest volume chemical used in industry

- S(s) + O2(g) -----> SO2(g)

- SO2(g) + H2O(l) -----> H2SO3(aq) = sulfurous acid

e. We will be burning S(s) in the hood to produce H2SO3

- Use same procedure as for phosphorous

- All waste P and S should be completely burned off of the spoon

f. Sulfur has more than one Allotrope

- Two allotropes of solid sulfur have 8-membered rings, but different crystal forms: “monoclinic” and “rhombic”

- If liquid sulfur is cooled quickly, it solidifies as chains of sulfur atoms called “plastic sulfur”

monoclinic rhombic plastic

C. Group 7A = Halogens (kJ/mol)

1. Elements Element Type StateE.A.

a. F = Fluorine Non-metal diatomicgas, yellow -328

b. Cl = Chlorine Non-metal diatomicgas, yellow -349

c. Br = Bromine Non-metal diatomic liquid, brown -325

d. I = Iodine Non-metal diatomic solid, purple -295

e. At = Astatine Non-metal radioactive solid

2. The chemistry of these elements is dominated by their need to add one e-

2 Na(s) + Cl2(g) -----> 2 NaCl(s) + large amount of heat

Sodium Reacts Violently with Chlorine

3. Electron Affinity = energy given off when a gaseous element gains an e-

a. X(g) + e- -----> X-(g)

b. Exothermic process because all elements accept e- due to + nucleus

c. Adding e- is less favored down a group due to distance from nucleus

d. Fluorine is so small, that repulsion from other electrons lowers its E.A.

4. Halogens with more favorable E.A. can take electrons from other halides

a. Cl2 + 2 Br- -----> 2 Cl- + Br2

b. E.A: -349 -325

c. Cl2 is reduced; Br- is oxidized

5. We will be studying this kind of reaction today in lab

a. Prepare control samples:

- I2/H2O + toluene = purple color of I2 in toluene

- Br2/H2O + toluene = orange color of Br2 in toluene

- Cl2/H2O + toluene = yellow color of Cl2 in tolueneCl2

Br2

I2

b. Run all possible combinations of reactions between Cl/Br/I and observe the color of the toluene when finished

Cl2 + Br- -----> yellow (Cl2) if no reaction; orange (Br2) if reaction

Cl2 + I- ----->

Br2 + Cl- ----->

Br2 + I- -----> orange (Br2) if no reaction; purple (I2) if reaction

I2 + Cl- ----->

I2 + Br- ----->

c. Use parafilm to cover test tubes to shake them up

d. All halogen reactions go into a waste beaker in the hood

Incident: HF and Trifluoroacetic Acid Burn

Incident: HF Exposure