Characteristics of the Groups on the Periodic Table
Groups are the eighteen series of elements in columns across the table. For instance, the elements in group one (the alkali
metals) are hydrogen, lithium, sodium, potassium, rubidium, caesium and francium. Each of these groups is special for the
common characteristics their constituent elements share.
Alkali Metals (Group 1)- Color this group Green
- do not occur elementally in nature
- have one valence electron
- have low ionization energies
- form colorless ions, each with a +1 charge
- are reactive metals obtained by reducing the +1 ions in their natural compounds
- are stored under kerosene or other hydrocarbon solvent because they react with water vapor or oxygen in air
- form water-soluble bases
- are strong reducing agents
- are good conductors of electricity and heat
- are ductile, malleable, and soft enough to be cut with a knife
- have a silvery luster, low density, and a low melting point
Alkaline Earth Metals (Group 2)- Color this group Blue
- do not occur elementally in nature
- occur most commonly as carbonates, phosphates, silicates, and sulfates
- occur naturally as compounds that are either insoluble or only slightly soluble in water
- contain two valence electrons
- tend to lose two electrons per atom, forming ions with a +2 charge
- are less reactive than alkali metals
- primarily form ionic compounds
- react with water to form bases and hydrogen gas
- are good conductors of heat and electricity
- are ductile and malleable
- have a silvery luster
- include the naturally radioactive element radium
Transition Metals (Groups 3-12)- Color this group Purple
- consist of metals in groups 3 through 12
- contain one or two valence electrons
- are usually harder and more brittle than metals in groups 1 and 2
- have higher melting and boiling points that metals in groups 1 and 2
- are good conductors of heat and electricity
- are malleable and ductile
- have a silvery luster, except copper and gold
- include radioactive elements 89 through 109
- include mercury, the only metal that is liquid at room temperature
- have chemical properties that tend to differ from each other
- tend to have two or more common oxidation states
- often form colored compounds
- may form complex ions
Information on this handout from http://library.thinkquest.org/C0110203/char.htm; Information about the Rare Earth
elements from: http://chemistry.about.com/od/elementgroups/a/rareearths.htm; Information about Metalloids from:
http://chemistry.about.com/od/elementgroups/a/metalloids.htm
Boron Family (Group 13)
- do not occur elementally in nature
- are scarce in nature (except aluminum, which is the most abundant metallic element)
- have three valence electrons
- are metallic (except boron, which is a solid metalloid)
- are soft and have low melting points (except boron, which is hard and has a high melting point)
- are chemically reactive at moderate temperatures (except boron)
Carbon Family (Group 14)
- includes a nonmetal (carbon), two metalloids (silicon and germanium) and two metals (tin and lead)
- vary greatly in both physical and chemical properties
- occur in nature in both combined and elemental forms
- have four valence electrons
- are relatively unreactive
- tend to form covalent compounds (tin and lead also form ionic compounds)
Nitrogen Family (Group 15)
- consists of two nonmetals (nitrogen and phosphorus), two metalloids (arsenic and antimony), and one metal (bismuth)
- nitrogen is most commonly found as atmospheric N2, phosphorus as phosphate rock, and arsenic, antimony, and bismuth
as sulfides or oxides; antimony and bismuth are also found elementally
- range from very abundant elements (nitrogen and phosphorus) to relatively rare elements (arsenic, antimony, and
bismuth)
- have five valence electrons
- tend to form covalent compounds, most commonly with oxidation numbers of +3 or +5
- are solids at room temperature, except nitrogen
Oxygen Family (Group 16)
- occur elementally in nature and in combined states
- consists of three nonmetals (oxygen, sulfur, and selenium), one metalloid (tellurium), and one metal (polonium)
- have six valence electrons
- tend to form covalent compounds with other elements
- tend to exist as diatomic and polyatomic molecules, such as O2, O3, S6, S8, and Se8
- commonly exist in compounds with the -2 oxidation state, but often exhibit other oxidation states
Halogen Family (Group 17)- Color this group Red
- are nonmetals and occur in combined form in nature, mainly as metal halides
- are found in the rocks of Earth's crust and dissolved in sea water
- range from fluorine, the 13th most abundant element, to astatine, which is one of the rarest
- exist at room temperature as a gas (F2 and Cl2), a liquid (Br2), and a solid (I2 and At)
- have seven valence electrons
- tend to gain one electron to form a halide, X- ion, but also share electrons and have positive oxidation states
- are reactive, with fluorine being the most reactive of all nonmetals
Noble Gases (Group 18)- Color this group Gold or Yellow
- not reactive
- have a full outer energy level
- are all gases
- are all nonmetals
Information on this handout from http://library.thinkquest.org/C0110203/char.htm; Information about the Rare Earth
elements from: http://chemistry.about.com/od/elementgroups/a/rareearths.htm; Information about Metalloids from:
http://chemistry.about.com/od/elementgroups/a/metalloids.htm
Common Properties of the Rare Earths Color this group Pink
These common properties apply to both the lanthanides and actinides and are located in the two
rows below the periodic table.
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The rare earths are silver, silvery-white, or gray metals.
The rare earths are solid at room temperature.
The metals have a high luster, but tarnish readily in air.
The metals have high electrical conductivity.
The rare earths share many common properties. This makes them difficult to separate or
even distinguish from each other.
There are very small differences in solubility and complex formation between the rare
earths.
The rare earth metals naturally occur together in minerals (e.g., monazite is a mixed rare
earth phosphate).
Rare earths are found with non-metals, usually in the 3+ oxidation state. There is little
tendency to vary the valence. (Europium also has a valence of 2+ and cerium also a valence
of 4+.)
Metalloids- Color this group Orange
Location on the Periodic Table
The metalloids or semimetals are located along the line between the metals and nonmetals in the periodic
table. The metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Polonium is often
considered a metalloid, too.
Properties
The electronegativities and ionization energies of the metalloids are between those of the metals and
nonmetals, so the metalloids exhibit characteristics of both classes. Silicon, for example, possesses a metallic
luster, yet it is an inefficient conductor and is brittle. The reactivity of the metalloids depends on the element
with which they are reacting. For example, boron acts as a nonmetal when reacting with sodium yet as a
metal when reacting with fluorine. The boiling points, melting points, and densities of the metalloids vary
widely. The intermediate conductivity of metalloids means they tend to make good semiconductors.
Summary of Common Properties
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Electronegativities between those of metals and nonmetals
Ionization energies between those of metals and nonmetals
Possess some characteristics of metals/some of nonmetals
Reactivity depends on properties of other elements in reaction
Often make good semiconductors
Information on this handout from http://library.thinkquest.org/C0110203/char.htm; Information about the Rare Earth
elements from: http://chemistry.about.com/od/elementgroups/a/rareearths.htm; Information about Metalloids from:
http://chemistry.about.com/od/elementgroups/a/metalloids.htm