The Periodic Table’s Groups, Families, and Periods

Regions of the Periodic Table

Groups…Here’s Where the Periodic Table Gets Useful Elements in the same group have similar chemical and physical properties. (Mendeleev did that on purpose.) Why?? They have the same number of valence electrons. Think: Happy atoms! They will form the same kinds of compounds.

Families on the Periodic Table Columns are also grouped into families. Families may be one column, or several columns put together. Families have names rather than numbers. (Just like your family has a common last name.)

Families on the Periodic Table Families are based on their similar chemical properties. Each family has a specific name to differentiate it from the other families in the periodic table. Elements in each family act like other members and act differently than elements in other families.

Hydrogen Hydrogen belongs to a family of its own. Hydrogen is a diatomic, nonmetallic, reactive gas. Hydrogen was the fuel involved in the explosion of the Hindenberg. Hydrogen is promising as an alternative fuel source for automobiles

Group 1: Alkali Metals Cutting sodium metal Reaction of potassium + H2O Cutting sodium metal

ALKALI METALS Hydrogen is not a member, it is a non-metal 1 electron in the outer shell Soft and silvery metals Very reactive, especially with water Conduct electricity Image: http://www.learner.org/interactives/periodic/groups2.html

Alkali Metals Very reactive metals, so they are never found alone in nature – they are always combined with other elements. Soft enough to cut with a butter knife

Group 2: The Alkaline Earth Metals Magnesium Magnesium oxide

ALKALINE EARTH METALS 2 electrons in the outer shell White and malleable Reactive, but less than alkali metals Conduct electricity

Alkaline Earth Metals Reactive metals that are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca).

Transition Metals Columns 3 - 12 Less reactive, harder metals Includes metals used in jewelry, coins and construction. What we think of as “metal”.

TRANSITION METALS Good conductors of heat and electricity. Groups in the middle Good conductors of heat and electricity. The transition metals are able to put up to 32 electrons in their second to last shell. Can bond with many elements in a variety of shapes.

PURE METALS Pure metals have certain properties. Metals are: Good conductors of heat. Good conductors of electricity. Malleable - they can be hammered into different shapes Ductile - they can be drawn into wire Solids are room temperature with the exception of mercury, which is a liquid.

BORON FAMILY Group 13 3 electrons in the outer shell Most are metals Exception: Boron is a metalloid

Boron Family Aluminum was once rare and expensive, not a “disposable metal.” It is the most common metal.

CARBON FAMILY Group 14 4 electrons in the outer shell Contains metals, metalloids, and a non-metal, Carbon (C)

Carbon Family Contains elements important to life and computers. Carbon is the basis for an entire branch of chemistry. Si and Ge are important semi-conductors.

NITROGEN FAMILY Group 15 5 electrons in the outer shell Share electrons to form compounds Contains metals, metalloids, and non-metals

Nitrogen Family Nitrogen makes up over ¾ of the atmosphere. Nitrogen and phosphorus are both important in living things. The tip of a match is phosphorus.

Oxygen Family or Chalcogens Elements in column 16 Oxygen is necessary for respiration. Many things that stink contain sulfur (rotten eggs, garlic, skunks, etc.)

OXYGEN FAMILY Group 16 6 electrons in the outer shell Contains metals, metalloids, and non-metals. Reactive

Group 17: The Halogens (salt makers) F, Cl, Br, I, At

Halogens 7 electrons in the outer shell All are non-metals Very reactive -are often bonded with elements from Group 1

Halogens Elements in group 17 Volatile, diatomic, nonmetals Always found combined with other element in nature . Used as disinfectants and to strengthen teeth.

Group 18: The Noble (Inert) Gases He, Ne, Ar, Kr, Xe, Rn Helium balloons “Neon” signs Very unreactive as they have full electron levels XeOF4

The Noble Gases Noble Gases are also called the Inert Gases. Elements in group 18 are VERY unreactive. Used in “neon” signs.

Noble Gases Exist as monatomic gases Non-metals 8 electrons in the outer shell = Full Exception: Helium (He) has only 2 electrons in the outer shell = Full

Rare Earth Metals Some are radioactive The rare earths are silver, silvery-white, or gray metals. Conduct electricity

Rare Earth Metals Composed of the Top row: Lanthanides and the Bottom row: Actinides Many of the Rare Earth elements are radioactive. Beyond #92, they are called “transuranium elements” After #94, all are synthetic (man-made).

There are many other patterns we can find on the PT. Trends There are many other patterns we can find on the PT.

Metals Metals vs. nonmetals Nonmetals The periodic table can be classified by the behavior of their electrons. Metals tend to give up electrons and form cations (+ charged ions). Metalloids may either give up or accept electrons. Non-metals tend to accept electrons and form anions (- charged ions). Metals Nonmetals

Trend in Electron Affinity Electron affinity: the energy change when a neutral atom attracts an electron to become a negative ion.

2. Trend in Electronegativity As you move from left to right across a period, the ability of the atom to attract another electron increases; this property is known as electro-negativity. As there are more protons, more electrons are attracted, but as you go down a group, electronegativity decreases because the electrons are increasingly distant from the nucleus.

3. Trend in Atomic Radius The decrease in radius is due to the increasing number of protons in the nucleus. The electrical attraction between the nucleus and the orbiting electrons gets stronger and pulls the electrons closer to the nucleus The size decreases as we go from left to right across a period. The size increases as we go down a row. Largest atoms are found in the SW corner of the PT, while the smallest are in the NE.

4. Trend in Ionization Potential Ionization potential: The energy required to remove the valence electron from an atom. Largest toward NE corner of PT since these atoms hold on to their valence e- the tightest.