CHE 2C- Ch.18 Main Group

Representative elements

Chemical Properties are determined by the valence - level s and p electrons

Transition metals:

result from filling of d orbitals

Lanthanides:

Correspond to the filling of the 4f orbitals

Actinides:

Correspond to the filling of the 5f orbitals

Metalloids (semimetals):

Elements along the division line between metals and nonmetals in the periodic table Ex: silicon and germanium

Metalloids:

Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium, Astatine

metal exception

Hydrogen

Characterizing metals

-Form cations by losing valence electrons -Exhibit electron conf of the noble gas from the preceding period

Characterizing nonmetals

-Form anions by gaining electrons -Exhibit electron config of the noble gas in the same period

Metallic character is observed to ___________ going down a given group and are consistent with trends in _,, and _______

-increase -ionization energy -electron affinity -electronegativity

__________ in atomic ______ between the ______ and _____ member of a group cause the first element to exhibit different properties

Difference radii 1st 2nd

Group 1A: Hydrogen & Lithium

Hydrogen: non-metal Lithium: active metal

Group 2A: Oxides of metals & exception

are basic exceptions: Beryllium oxide which is amphoteric

Group 3A: Boron

acts as nonmental or sometimes a semimetal

Group 4A: Carbon and Silicon bonds

Si-O bonds are the most reactive, then Si-Si, then C-C

Group 5A: Nitrogen & Phosphorus

exists as a diatomic molecule Phosphorus forms larger aggregates of atoms

Group 6A: Oxygen

exists in the most stable form as diatomic molecule O2

Group 7A: Fluorine

has smaller electron affinity than chlorine

Metallurgy:

Process of obtaining a metal from its ore Involves reducing ions to their elemental metal

Most abundant non-metal

Oxygen

Most abundant metal

Aluminum

Most abundant element in the human body

Oxygen

Electrolysis Preparation of Oxygen and Nitrogen: ______ & ________

conversion to liquid through liquefaction separated by distilling liquid air

Hydrogen can be obtained from:

Electrolysis of water Decomposition of methane in natural gas

Sulfur obtained from:

elemental form found underground recovered by the Frasch process

Halogens obtained by:

oxidation of anions from halide salts

1A electron config & exception

ns^1 exception H (non-metal)

elements essential for the proper functioning of nerves and muscles

Sodium (Na) and Potassium (K)

Method of preparation: Lithium

Electrolysis of molten LiCl

Method of preparation: Sodium

Electrolysis of molten NaCl

Method of preparation: Potassium

Electrolysis of molten KCl

Method of preparation: Rubidium

Reduction of RbOH with Mg and H2

Method of preparation: Cesium

Reduction of CsOH with Mg and H2

Li2O is composed of Li+ and O2- this is called

oxide salt

Na2O2 is composed of Na+ and O2^(2-) this is called

peroxide salt

KO2 is composed of K+ and O2- this is called

superoxide salt

Which of the following is the strongest reducing agent in the gas phase?

a) Li b) Na c) K d) Rb e) Cs

e) Cs

Which ions are very important for the proper functioning of biologic systems, such as nerves and muscles?

a) Alkaline earth metal ions b) Alkali metal ions c) Oxygen ions d) Sulfur ions e) Nitrogen ions

b) Alkali metal ions

Physical properties of Hydrogen

colorless, odorless gas composed of H2 molecules low molar mass and non-polar Highly flammable -Air that contains 18%- 60% = explosive

Industrial source is the _____

Reaction of methane with water at high temperatures

Electrolysis of water

produces pure hydrogen

By-product of gasoline production

When hydrocarbons with high molecular masses are cracked (broken down) to produce smaller molecules that can be used as motor fuel

Industrial use

Production of ammonia by the Haber process

Hydrogenation of unsaturated vegetable oils

Hydrogen is used in large quantities to produce solid shortenings that are saturated (have carbon-carbon single bonds).

Hydrogen behaves as a typical non-metal, so it forms

•Covalent compounds with other nonmetals •Salts with active metals

Hydrides are

Binary compounds containing hydrogen

Ionic (Saltlike) Hydrides form when hydrogen combines with the

most active metals (Groups 1A and 2A)

Hydride ion acts as a strong ________ agent

reducing agent (strong base) due to presence of 2 electrons

Covalent Hydrides formed___?

when hydrogen combines with other nonmetals

Most important covalent hydride

Water (H2O)

Unusual Properties of Water

High boiling point Large heat of vaporization Higher density in liquid form than in solid form Excellent solvent for ionic and polar substances

Metallic (Interstitial) Hydrides

•Formed when transition metal crystals are treated with hydrogen gas

Small hydrogen atoms migrate into the crystal structure and occupy

•interstices (holes)

Lose much of the absorbed hydrogen as gas when ________

heated

Metallic (Interstitial) Hydrides Offer Possibilities for storing Hydrogen for use as a

Portable Fuel

Alkaline Earth Metals are

very reactive owing to the basicity of their oxides

Alkaline Earth Metals are more active are results in

when reacting with water H2 gas

Which Alkaline Earth Metals react vigorously

Ca, Sr, Ba

Which Alkaline Earth Metals show no reaction and because it is

Be, Mg less easily oxidized

Mg reacts with

boiling water

Calcium are found in the structural minerals that compose

bones and teeth

Magnesium is essential in ______ function

metabolism and muscle function

Magnesium is useful for _________ material because ?

structural low density and moderate strength

Method of Preparation: Beryllium

Electrolysis of molten BeCl2

Method of Preparation: Magnesium

Electrolysis of molten MgCl2

Method of Preparation: Calcium

Electrolysis of molten CaCl2

Method of Preparation: Strontium

Electrolysis of molten SrCl2

Method of Preparation: Barium

Electrolysis of molten BaCl2

Method of Preparation: Radium

Electrolysis of molten RaCl2

Hard Water

•Natural water that contains Ca2+ and Mg2+ interferes with the action of detergents and forms precipitates with soap.

Ion exchange

Process that removes Ca2+ and Mg2+ in individual homes (Water Softener) Na+ is released into the soln

Ion-exchange resin

consists of large molecules (polymer) that have many ionic sites

•Which of the following ions interfere(s) with the action of detergents in hard water? a.Na+ b.Ca2+ c.Mg2+ d.Ca2+ and Mg2+ e.Na+, Ca2+, and Mg2+

d. Ca2+ and Mg2+

Group 3A exhibits increase in __________ in going down the group

metallic character

Boron is technically a __________ but it generally acts as a typical & forms

metalloid nonmetal covalent compounds

Boranes is _________ compounds of boron

Covalent hydride

Diborane is the _________ one & written as

simplest B2H6

Boranes reacts __________ with oxygen

exothermically with oxygen

•Once evaluated as fuels for rockets in the U.S. space program

Boranes

Method of Preparation: Boron

Reduction by Mg or H2

Method of Preparation: Aluminum

Electrolysis of Al2O3 in molten Na3AlF6

Method of Preparation: Gallium

Reduction with H2 or electrolysis

Method of Preparation: Indium

Reduction with H2 or electrolysis

Method of Preparation: Thallium

Electrolysis

Aluminium contains ______ properties

metallic Ex: conducts heat and electricity & lustrous appearance

Aluminium forms covalent bonds with _________

nonmetals

Gallium has properties like

the largest liquid range of any metal

Thallium is completely

metallic

•How many of the following statements are false? I.The Group 3A elements are all metals II.Alkaline earth metals react less vigorously with water than do the alkali metals III.Salts can consist of hydrogen IV.Because Li is the strongest reducing agent among the alkali metals, it reacts most quickly with water of all the alkali metals

I, IV

•Which of the following is the most abundant metal on earth? a.Calcium b.Iron c.Copper d.Aluminum e.Zinc

d.Aluminum

Fundamental constituent of molecules that are necessary for life

Carbon

Forms the Basis for the Geological world

Silicon

Group 4A can form ____ covalent bonds to nonmetals

four

Forms pi bonds (double and triple bonds)

Carbon

Carbon is dominated by which bonds

Carbon- Carbon Bonds

Silicon is dominated by which bonds

Silicon - Oxygen bonds

Carbon occurs in allotropic forms of _____, _____, and _______

graphite, diamond, and fullerenes

Silicon is a semimetal that is found widely distributed in

silica and silicates

Germanium is a rare metal and semimetal used in manufacturing

semiconductors for transistors

Tin is a soft silvery metal and ___________ is a famous ____________ agent

SnCl2 reducing