The Periodic Table A Dmitri Mendeleev a In

The Periodic Table

A. Dmitri Mendeleev a. In 1869 arranged elements in order of increasing atomic mass b. He left vacant spaces in his table where unknown elements could fit . Dmitri Mendeleev was so confident in his table that he used it to predict the physical properties of three elements that were yet unknown-Sc, Ga and Gewhich were later discovered between 1874 and 1885

B. 1. 2. Geography of the Modern Table 7 periods (rows)-Row number indicates the number of energy levels an atom has Groups or Families (A Groups)-Column # indicates # of valence (outside/bonding) electrons ( those with 8 don’t bond-more later) – elements with similar properties (also called representative elements) are placed in these groups and these groups have names

Hydrogen n n Hydrogen belongs to a family of its own. 1 valance electron Hydrogen is a diatomic, reactive gas. Hydrogen was involved in the explosion of the Hindenberg. Hydrogen is promising as an alternative fuel source for automobiles

H

Alkali Metals-Group 1 A n n n 1 valence electron Very reactive metals, always combined with something else in nature (like in salt). Soft enough to cut with a butter knife

Alkali Metals H

Alkaline Earth Metals. Group 2 A n n n 2 valence electrons Reactive metals that are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca

Alkaline Earth Metals Alkali Metals H

Transition Metals-B Groups n Elements in groups 3 -12 – Valence electrons vary n n n Less reactive harder metals Includes metals used in jewelry and construction. Metals used “as metal. ”

Alkaline Earth Metals Alkali Metals H Transition Metals

Boron Family-Group 3 A n n n 3 valence electrons Elements in group 13 Aluminum metal was once rare and expensive, not a “disposable metal. ”

Alkaline Earth Metals Alkali Metals Transition Metals Boron Family H

Carbon Family-Group 4 A n n 4 valence electrons Contains elements important to life and computers. – CARBON is found in ALL living things – Carbon is the basis for an entire branch of chemistry. n Silicon and Germanium are important semiconductors.

Alkaline Earth Metals Alkali Metals Transition Metals Carbon Family Boron Family H

Nitrogen Family-Group 5 A n n n 5 valence electrons Nitrogen makes up over ¾ of the atmosphere. Nitrogen and phosphorus are both important in living things. Most of the world’s nitrogen is not available to living things so it is “fixed” by special bacteria in the roots of plants (peanuts too!). The red stuff on the tip of matches is phosphorus.

Alkaline Earth Metals Alkali Metals Transition Metals Nitrogen Family Carbon Family Boron Family H

Oxygen Family(Chalcogens)Group 6 A n n n 6 valence electrons Oxygen is necessary for respiration. Many things that stink, contain sulfur (rotten eggs, garlic, skunks, etc. )

Alkaline Earth Metals Alkali Metals Transition Metals Oxygen Family Nitrogen Family Carbon Family Boron Family H

Halogens-Group 7 A n n 7 Valence electrons Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature. Used to make salts, disinfectants and to strengthen teeth.

Alkaline Earth Metals Alkali Metals Transition Metals Halogens Oxygen Family Nitrogen Family Carbon Family Boron Family H

The Noble Gases-Group 8 A n n 8 valence electrons so they have a full outer energy shell. VERY unreactive, Used in lighted “neon” signs Used in blimps to fix the Hindenberg problem.

Metals Lanthanide Series Actinide Series Lanthanides and actinides are also called the “Rare Earth elements. Actinides are radioactive. Noble Gases Transition Metals Halogens Alkaline Earth Metals s al et -M on N Alkali Metals H

3. Periodic Law-patterns within the table as we move left to right and top to bottom – Atomic Number (number of protons) increases from left to right across a period. – Atomic mass (number of p+ and n) increases from left to right across a period. – Density increase from top to bottom and left to right as we add more atom particles – Metals on the left-nonmetals on the right

Properties of Metals q Metals are good conductors of heat and electricity q Metals are malleable (can be molded) q Metals are ductile (can be drawn into a wire) q Metals have high tensile strength q Metals have luster (shine)

Properties of Metalloids straddle the border between metals and nonmetals on the periodic table. v They have properties of both metals and nonmetals.

NON-METALS Opposite properties to metals very brittle exist in two of the three states of matter at room temperature: most are gases [such as oxygen (diatomic-O 2) and a few solids (such as carbon).

Examples of Nonmetals Sulfur, S, was once known as “brimstone” Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure Microspheres of phosphorus, P, a reactive nonmetal