History of the Periodic Table Mrs. Hardeman

Russian chemist Dimitri Mendeleev proposed arranging elements by atomic weights and properties!! A few elements seemed to be out of place!!!!

Soon after Rutherford’s discovery of the nucleus, I subjected the known elements to x-rays. I was able to derive the relationship between x-ray frequency and the # of protons(the Atomic Number). Moseley arranged a new Periodic Table according to Atomic # and many of the “mistakes” with Mendeleev’s table were corrected!!! Henry Moseley

Who developed the 1st Periodic Table? Mendeleev Moseley Eidson Hatfield

Whose Periodic Table was arranged in order of increasing Atomic #? Mendeleev Moseley Eidson Hatfield

Metals Most are solids. Metals are opaque, lustrous elements. Are good conductors of heat and electricity. Most metals are malleable and ductile. Most are, in general, denser than the other elemental substances.

Nonmetals Great insulators Poor conductors of heat and electricity when compared to metals. Great insulators Most are gases. In solid form, they are dull and brittle. Usually have lower densities than metals They have significantly lower melting points and boiling points than metals Nonmetals usually have little or no luster.

Metalloids Have properties of both metals and non-metals. Ex.) Will conduct heat better than non-metals, but not as good as metals. Some are considered semi-conductors of electricity which makes them useful for computers.

Which of the following elements is a metal? Carbon Silicon Sodium Chlorine

Which of the following elements is a nonmetal? Carbon Silicon Sodium Lithium

Which of the following elements is a metalloid? Carbon Silicon Sodium Chlorine

Periods—horizontal rows on the table(7) Family(groups)—vertical columns on the table(18)

Valence Electrons The valence electrons are the electrons in the last shell or energy level of an atom. They do show a repeating or periodic pattern. The valence electrons increase in number as you go across a period. Then when you start the new period, the number drops back down to one and starts increasing again. “We can check this with a few drawings! ”

Draw Hydrogen How many valence electrons? 1

Draw Lithium How many valence electrons? 1

Draw Sodium How many valence electrons? 1

Draw Berylium How many valence electrons? 2

Draw Magnesium How many valence electrons? 2

Do you notice the Trend?

Valence Electrons(cont) We could actually draw any of the families and we would see that the # of valence electrons is the same throughout any of the families!!

Valence Electrons

How many valance electrons does Oxygen have? 3 4 6 8

How many valance electrons does Krypton have? 3 4 6 8

How many valance electrons does Magnesium have? 1 2 3 4

Chemical Families

Alkali Metals Group 1 Except Hydrogen. Composed of highly reactive(active) metals. 1 valence electron Tend to lose 1 electron to form compounds(+1) React vigorously with water. In nature, they are never found in their pure state. React with halogens to form salts.

Alkaline Earth Metals Composed of reactive metals. 2 valence electrons Tend to lose 2 electrons to form compounds(+2). Compounds of alkaline earth metals comprise many common minerals. Many are used in fireworks.

Transition Metals They are usually have high melting points. They have several oxidation states. Typically, +2 or +3

Boron Family 3 valence electrons Tend to lose three electrons and form positive ions(+3).

Carbon Family The elements of the Carbon Family show great versatility. Carbon is the basis for organic chemistry and forms more compounds than any other element except hydrogen. 4 valence electrons Gain, lose, share(+/- 4)

Nitrogen Family 5 valence electrons. Typically gains 3 electrons(-3) Nitrogen is the principal constituent of the air. Many are used in fertilizers.

Oxygen Family 6 valence electrons Typically gains 2 electrons(-2) Oxygen makes up nearly half of the Earth's crust by mass. Oxygen produced by plants sustains life.

Halogens 7 valence electrons Typically gain 1 electron(-1) Most active non-metals. Halogen means "salt formers". They lack only one electron to form a complete shell. Tend to gain an electron to form compounds.

Nobel Gases 8 valence electrons(except He has 2) Will not gain or lose electrons(0) Gases which have closed shells Are unreactive chemically. “Neon” lights.

A NG AE Family Names H TM

Sodium(Na) belongs to which chemical family? Alkali Metals Alkaline Earth Metals Halogens Nobel Gases

Chlorine(Cl) belongs to which chemical family? Alkali Alkaline Earth Halogens Nobel Gases

Calcium(Ca) belongs to which chemical family? Alkali Alkaline Earth Halogens Nobel Gases

Xenon(Xe) belongs to which chemical family? Alkali Alkaline Earth Halogens Nobel Gases

Attention: New Additions to Periodic Table WOMANIUM (Wo) Physical properties: Generally soft and round in form. Boils at nothing and may freeze any time. Very bitter if not used well. Chemical properties: Very active and highly unstable. Possesses strong affinity with gold, silver, platinum, and precious stones. Violent when left alone. Turns slightly green when placed next to a better specimen. Usage: An extremely good catalyst for dispersion of wealth. Caution: Highly explosive in inexperienced hands! MANIUM (Xy) Physical properties: Solid at room temperature but gets bent out of shape easily. Difficult to find a pure sample. Due to rust, aging samples are unable to conduct electricity as easily as young samples. Chemical properties: Attempts to bond with WO any chance it can get. Also tends to form strong bonds with itself. Becomes explosive when mixed with Childrium for prolonged period of time. Usage: Possibly good methane source. Caution: In the absence of Wo, this element rapidly decomposes and begins to smell.

Color your Periodic Table: Label # of valence electrons with a color. Label Family Names and color each with a different color. Draw a “box” around Hydrogen and Label “NM”. Place a big “M” over the metals, a “NM” over the nonmetals and circle the metalloids.