The Periodic Table of Elements (AKA THE MOST AWESOME THING EVER!) 1
2
The Development of the Periodic Table of Elements In 1869, Dmitri Mendeleev was studying the physical and chemical properties of the elements when he realized that, if the elements are arranged in order of increasing atomic weight, elements with similar properties appear in a regular pattern. He began lining up the elements in a row: Li, Be, B, C, N, O, F The next known element at the time was sodium (Na). Since its properties most resembled that of lithium (Li), he created a new row. So, in addition to horizontal rows, there were now vertical columns. 3
The Development of the Periodic Table of Elements Mendeleev continued to fill in his table using chemical and physical properties of the elements known at the time. Remarkably, he left empty spaces if an element SHOULD exist, but was not known at the time (genius!) However, he noticed that there were discrepancies by listing them in order of atomic weight. In 1913, G.J. Moseley corrected Mendeleev s assumption. Moseley realized that these discrepancies could be eliminated by listing them in order of atomic number. 4
Features of the Periodic Table Each square on the periodic table represents a different element Carbon 6 C 12.011 Element Name Atomic Number Chemical Symbol Atomic Weight 5
Features of the Periodic Table Elements are arranged so that those with similar physical and chemical properties lie in vertical columns called groups or families In the United States, the groups are numbered 1-8 followed by a letter: A or B. The A groups are known as the main group elements The B groups are called transition elements 6
Features of the Periodic Table The horizontal rows of the periodic table are called periods The periodic table is divided into several regions according to the properties of those elements Light blue: Metals Dark blue: Transition metals Green: Metalloids Yellow: Non-metals 7
Properties of Metals (Including Transition Metals) Metals are solids at room temperature, except for Mercury (Hg) which is a liquid They can conduct electricity, are ductile (can be drawn into wires), and malleable (can be hammered into sheets) Some metals can form solutions called alloys. Alloys are mixtures of metals! 8
Properties of Nonmetals At room temperature: Some are solids (C, S, P, and I 2 ) Some are gases (H 2, O 2, N 2, F 2, Cl 2 ) One is a liquid (Br 2 ) Unlike metals, they do not conduct electricity. The exception is carbon when it is in the form of graphite. 9
Properties of Metalloids (or semimetals) These elements have properties that make them difficult to classify Some have physical properties of a metal, but chemical properties of nonmetals Scientists often disagree about which elements fit into this category http://periodictable.com/ 10
Alkali Metals Noble Gases Alkaline Earth Metals Halogens Transition Metals Lanthanides and Actinides Slide 11 of 25
Elements are arranged so that those with similar physical and chemical properties lie in vertical columns called groups or families Group 1A Group 2A Group 7A Group 8A Alkali Metals Alkaline Earth Metals Halogens Noble Gases Soft metals React vigorously with water In nature, they are found in compounds All except Be react with water to form an alkaline solution Non-metals Highly reactive Exist as diatomic molecules F 2 Cl 2 Br 2 I 2 Stable gases Least reactive of all the elements https://www.youtube.com/watch?v= eachisv5ur0 https://www.youtube.com/watch?v= u2ogmudbaf4 12
Features of the Periodic Table The periodic table is also useful for determining electron configuration The electron configuration of an element provides critical insight to its reactivity We will return to this table later when we discuss ions and ionic compounds 13
It s time to play Periodic Table Bingo! 14