Periodic Table Group 1a-8a Notes

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Anderson Kuo
Period 1

CHAPTER 19 – The Representative Elements: Groups 1A through 4A

-19.1- A Survey of the Representative Elements

I. Elements

A. Representative Elements: Groups 1A through 8A
← Filling s and p orbitals
← First member of a group forms the strongest ( bonds; results in diatomic molecules

B. Transition Elements: center of the table
← Filling d orbitals

C. Lanthanides & Actinides: listed separately, on the bottom on the table ← Filling 4f and 5f orbitals

II. Metals/Nonmetals/Metalloids

A. Metals:
← Lose valence electrons to form cations
← Exhibiting valence electron configuration of the noble gas from the preceding period ← Metallic character increases going down a given group

B. Nonmetals:
← Gain electrons to form anions
← Exhibiting valence electron configuration of the noble gas in the same period.

C. Metalloids:
← separate metals from nonmetals

III. Abundance and Preparation

A. Oxygen – major element found in earth

B. 2nd most abundant element is silicon, found in earth’s crust, forms the basis of most sand, rocks and soil; most abundant metals are aluminum and iron, which are found in ores

C. Metallurgy:
← Process of obtaining a metal from its ore
← Always involves reduction
← Why metals? B/c metals are found in the form of cations. ← Carbon is often used in metallurgy; it is the primary reducing agent in the production of steel ← Carbon is the cheapest and most readily available industrial reducing agent for metallic ions

D. Liquefaction:
← The transformation of a gas to a liquid
← Based on the principle that a real gas cools when it expands. ← Process – After each expansion, part of the cooler gas is compressed, while the rest is used to carry away the heat of compression. The compressed gas is then allowed to expand again. Cycle is repeated. ← Main Idea – The remaining gas eventually becomes cold enough to form the liquid state. ← Examples> Elemental nitrogen & oxygen are obtained by this process, then separated by the distillation of liquid air.

-19.2- The Group 1A Elements

A. Alkali Metals
← ns1 valence-electron configurations
← Active metals; all react vigorously with water to release hydrogen gas

B. Lithium
← Lithium is the strongest of the alkali metals
← Results from the very large energy of hydration of the small Li+ ion. ← Relatively high charge density, the ion effectively attracts water molecules and releases a large quantity of energy ← Strongest reducing agent, but reacts more slowly with water than does sodium and potassium ← It has a higher melting point; does not become molten from the heat of reaction with water; smaller area of contact with water

C. Reactions with Oxygen
← Lithium is the only element that forms regular oxides of the general formula M2O in the presence of excess oxygen ← Sodium forms solid Na2O if the oxygen supply is limited, forms sodium peroxide

D. Superoxides
← A compound containing the O2- anion
← Potassium, Rubidium, and Cesium react with Oxygen to produce superoxides ← Superoxides release oxygen gas in reactions with water or carbon dioxide ← Useful in the self-contained breathing apparatuses used by firefighters ← Used in “airpacks” as emergency equipment in labs and production facilities in case toxic fumes are released

E. Alkali Metal Ions
← Important for proper functioning of nerves and mucles ← Examples: Na+ and K+ ions are present in all body cells and fluids ← The Li+ ions affect the levels of neurotransmitters, molecules that assist the transmission of messages along the nerve networks; used in treatment of manic-depressive patients

-19.3- Hydrogen

A. Properties
← Colorless, odorless gas composed of H2 molecules
← Low molar mass...
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