Chem II: Test 3 Nuclear Chem Concepts

1. How many elements are nonmetallic?

2. Most of the essential elements in biological systems are __________ (+ name the 6)

3. Which elements are the most unreactive?

4. What is the most abundant element in the universe?

1. 25

2. nonmetals (O, C, H, N P, S)

3. noble gases

4. Hydrogen (formed in first few seconds of Big Bang, colorless, odorless, nonposinous, too light to be found in Earth’s Atmosphere)

Properties of nonmetals

1. Solids (C, P₄, S₈, Se, I₂, including metalloids)

2. Liquids (Br)

3. Gases (H₂, O₂, N₂, F₂, Cl₂, and Noble Gases)

4. Nonmetals are more electronegative than metals

5. metal + nonmetal = ionic compound

6. nonmetal + nonmetal = covalent compound

Periodic Trends: periodic trends in atomic properties can be explained by trends in electron configurations

Hydrogen:

1. Binary Hydrides

   1. Ionic: Saline Hydrides (Group 1, 2 - except Be which forms a covalent hydride). d-block, TiH_1.8 and TiH₂, formed by heating transition metals in hydrogen, release H₂ upon heating, black powedery electrically conducting solids

   2. Covalent: Molecular Hydrides. p-block, nonmetals, volatile, NH₃, HCl, methane, (BeH₂)_x polymeric, discrete molecules, low melting points

   3. Interstitial: Metallic Hydrides. s-block, white, high-melting-point solids, electropositive metallic element + (H-)

Isotopes of Hydrogen

1. ¹H - Hydrogen - H - 99.985% abundance

2. ²H - Deuterium - D - 0.015% abundance

3. ³H - Tritium - T - t_1/2 12.5 yr

Big Bang Theory

• dominant scientific theory about the origin of the universe

• unverise created 10-20 billion years ago from a cosmic explosion that hurled matter in all directions

Alkali Metals Characteristics + Chemical Properties

1. most violently active of all metals

2. too easily oxidized to be found free in nature

3. pure metals obtained by electrolysis

4. Li - Hardest of Group 1 - still softer than lead

5. Most compounds are ionic

6. excellent reducing agents (can even reduce the hydrogen in water)

7. Reactivity with water increases down the group (Rb & Cs are denser than H₂O so they sink)

8. dissolve in liquid ammonia: the metals relsease their valence electrons which occupy cavities formed by groups of NH₃ molecules giving a ink-blue metal-ammonia solution. Increasing the concentration of the metal gives a metallic bronze solution

9. Alkali metals react directly with most non-metals (other than noble gases)

10. Only Li reacts with Nitrogen

Alkaline Earth Metals Characteristics + Chemical Properties

1. so called because the oxides of Ca, Sr, and Ba are basic

2. Too reactive to occur free in nature

   1. Dolomite - CaCO₃MgCO₃

   2. Limestone/calcite/chalk - CaCO₃

   3. Beryl - 3BeIAl₂O₃6SiO₂

3. Ca, Sr, and Ba are obtined by electrolysis or reduction with aluminum

4. Be doesn’t react with water; Mg burns in air & reacts with hot water; Ca reacts with cold water

5. partially passivated in air by a protective surface layer of oxide

6. have basic oxides and hydroxides

7. beryllium compounds are very toxic (highly polarized + small)

8. hydroxyapatite - Ca₅(PO₄)₃OH + Flourapatite Ca₅(PO₄)₃F = tooth enamel

Alkaline Earth Metals:

1. Calcium

2. Strontium

3. Barium

4. Radium

1. mineral in body that makes up bones and keeps them strong. 99% of Ca in body is stored in bones and teeth. remaining 1% is in blood and soft tissues and is essential for life and health. w/o this 1%, muscles wouldn’t contract correctly, blood wouldn’t clot, and nerves wouldn’t carry messages

2. produces glass for color television picture tubes

3. lustrous, machinable metal exists in nature only in ores containing mixtures of elements. used in electronic components, metal alloys, bleaches, dyes, fireworks, ceramins, drilling operations, & glass

4. radioactive metal naturally occuring in rocks, soils, & groundwater. as it decays, it continually releases energy into environment until stable, nonradioactive substance is formed. this energy is part of the natural radiation to which all living creatures are exposed. dissolves in acidic groundwater (224, 226, 228)

Boron Family Characteristics + Chemical Properties

1. B & Al (+3 oxidation), Ga & In & T1 (+1, +3 oxidation)

2. Inert-pair Effect: the tendency to form cations 2 units lower in charge than expected due to the different energies of valence “p” and “s” electrons. “s” electrons are poorly shielded from the nuclear charge and thus accessible

3. Boron: often classified as a metalloid, acidic oxides, boric acid - retards the spread of flames, hard + largely nonmetallic element, produced domestically in Cali, products sold on market are produced from a surface mine

4. Aluminum: most abundant metallic element in the earth’s crust, obtained by “hall process” (US aluminum industry is largest in world, producing annual amounts of > 22 bil lbs metal worth > $39 bil), light, strong, amphoteric, reactive metallic element with a surface that becomes passivated when exposed to air

5. Carbon: found free as diamond & graphite (allotropes), 0.09% by mass of Earth’s crust

Carbides

1. strong bronsted bases + carborundum

2. saline carbides: GI, GII, Al + C₂^2- or C^4-

3. covalent carbides: carbon & other nonmetals

4. interstitial carbides: d-block metal + carbon

Oxides of Carbon

1. CO: burns readily in oxygen to form CO₂. not an acidic oxide, toxic

2. CO₂: colorless and odorless gas, nontoxic, dry ice when solid, fire extinguishers and beverages

Silicon, Tin, Lead

1. metallic character increases significantly down group 14

2. lead used as a radiation shield, because its numerous electrons absorb high-energy radiation

1. What percent of air is Nitrogen?

2. Most important Hydrogen compound of a group 15 element, pungent toxic gas, colorless liquid at -33 C, weak bronsted base in water, strong Lewis base, gaseous state is very soluble in water bc NH₃ molecules can frorm Hydrogen bonds to H₂O molecules

3. Laughing Gas

4. Paramagnetic, highly toxic yellow-brown gas

5. Mixture of 1:3 ratio of HNO₃ to HCl

1. 78%

2. Ammonia (prepared by Haber process)

3. Nitrous oxide (N₂O)

4. Nitric Oxide (NO)

5. Aqua Regia (will oxidize gold)

Nitric Acid (HNO₃)

• used extensivley in the production of fertilizers and explosives, it produced by the 3 stage ostwald process

• it is a colorless liquid that boils at 83 C and is normally used in aquous solutions

• concnetrated nitric acid is often pale yellow as a result of partial decomposition of the acid to NO₂

Nitrites

• produced by reduction of nitrates with hot metal

• most are soluble in water and mildly toxic. Despite toxicity, they’re used in processing of meat products because they form a pink complex with hemoglobin and inhibit the oxidation of blood. Nitrites are responsible for the pink color of ham, sausages, and other cured meat

• In the body, nitrites can be convrted into nitrosamines, which are a class of chemicals that may be carcinogenic in humans. Bc of this, the US dept. of agriculture strictly limits the amounts of nitrates and nitrites in meat products.

Phosphorous

• found commonly in nature as phosphate rocks

• second most abundant element in the body after Ca

• white phosphorous and red phosophorous (allotropes)

• phosphorous is obtained from apatites, which are mineral forms of calcium phosphate. these rocks are heated in an electric furnace with carbon and sand

  • white phosphorous is formed from the condensed vapor

• red phosphorous is used in the striking surfaces of matchbooks and on the sides of boxes of safety matches

• increases algal growth and multiplication, choking out oxygen, and causing things to die via eutrophication

  • increase plant and animal biomass, increase growth of rooted plants, increase turbidity of water, increase sedimentation, development of anoxic conditions (anaerobic), decrease in species diveristy, change in dominant biota, & increase in frequency of algal blooms

Metalloids

B, Si, Ge, As, Sb, Te, Po

• have appearance and some physical properties of a metal but behave chemically like a nonmetal (good oxidizing agents, tend to form covalent bonds and molecular compounds by binding with nonmetals)

Oxygen Family (Group 16)

• aka Chalcogens

• name comes from Greek words meaning “brass giver” because the elements are found in copper ores and copper is a major component of brass.

• liquid oxygen is pale blue

• gas is colorless

• ozone is a blue gas

Sulfur

• 0.06% of Earth’s crust

• found in Gypsum

• found in natural gas as H2S, SO2

• S8 is yellow in color, tasteless, odorless solid

• Sulfur oxides: SO2 (sulfur dioxide), SO3 (Sulfur Trioxide), H2SO3 (Sulfurous Acid), H2SO4 (Sulfuric Acid)

  • Sulfuric Acid: colorless, strong acid, oily liquid, boils and decomposes at 300 C, strong acid, dehydrating agent, oxidizing agent

• Sulfuric Acid: world’s most important industrial chemical, strong dehydrating agent, strong oxidizing agent

• Sulfur Ores: Galena (PbS), Cinnabar (HgS), Pyrite (FeS2), Sphalerite (ZnS)

The Many Faces of Hydrogen Peroxide:

1. 30% Sol.

2. 6% Sol.

3. 3% Sol.

1. industrial use bc good oxidizing agent in both acidic and basic solutions

2. hair bleach via oxidizing pigment in hair

3. mild antiseptic in home + contact with blood catalyzes the disproportionation of hydrogen peroxide into water and gas, which cleanses the wound

Hydrogen (Group 17)

• flourine, chlorine, bromine, iodine are all reactive non-metals that are highly toxic

  • toxicity decreases from Flourine to Iodine

• HF has high boiling point bc hydrogen bonding

• astatine: all isotopes are radioactive

• Hydrogen Halides: HF used in etching glass & HCl used in metallurgical processes

• Acid Strength: (weakest) HF → HCl → HBr → HI (strongest)

Henri Moissan

successfully isolated F2 gas from the electrolysis of a mixed salt of KF and HF and noted that crystals of silicon burst into flame when mixed with the gas. Electrolysis of KHF2 is still used to prepare flourine today.

Noble Gases

• closed-shell electron configuration prompeted the belief that these elements were chemically inert

• 1962 XePtF6 was synthesized and shortly later, XeF4 was also isolated

• only Xenon is known to form an extensive series of compounds with Flourine and Oxygen. Xenon flourides are powerful flourinating agents, and Xenon oxides are powerful oxidizing agents

• Below 2 K, liquid helium shows remarkable property of superfluididty, the ability to flow without viscosity