History of the Periodic Table Chapter 5 section 1 Guided Notes

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1 History of the Periodic Table Chapter 5 section 1 Guided Notes By 1860, more than 60 had been discovered. Chemists had a hard time determining of the elements and compounds that the elements formed. They also had no accurate way to determine atomic or the number of atoms that made up an element, so each scientist used a different atomic mass making it nearly impossible for one chemist to the results of another. In 1860, chemists assembled at the First International Congress of Chemists in to settle the issue of atomic. Russian chemist Dmitri included the new values from the conference in a chemistry textbook that he was writing. He hoped to organize the elements according to their. He did this by placing the elements on cards and arranged them according to atomic mass and properties, looking for. He noticed that when the elements were arranged by atomic mass, similarities in the chemical properties appeared at regular intervals these patterns are. Mendeleev created a table in which the elements were grouped together by similar properties a periodic of. This table was published in and the properties were similar as you read across the table. This procedure left many spaces, but he predicted that elements would be and would fill those places - all three were discovered by was working with 38 different and discovered a that had not been recognized elements fit better when they were arranged by increasing charge (# of protons in nucleus). Moseley s work led to: Modern definition of atomic. Recognition that atomic NOT atomic is the basis for the of the periodic table. Law the and properties of the elements are periodic functions of their atomic (# of protons). Mendeleev understood the Periodic Law which states: When arranged by atomic number, the chemical elements display a and pattern of chemical and physical properties. with similar properties appear in or families (vertical columns) on the periodic table. They are similar because they all have the same number of (outer shell) electrons, which governs their chemical behavior.

2 The Modern Periodic Table Periodic table an arrangement of the elements in order of their atomic so that elements with similar properties fall in the same column or. The Gases Noble gases were the most significant to the periodic table. John William Strutt and Sir William Ramsay discovered a gas in the atmosphere that had not been noticed because it is and Helium a component of the. Ramsey added a new to the table to fit these gases. Lanthanides/ Actinides early 1900s. These are the elements with atomic number from 58 to 71 (lanthanides) and 90 to 103 (actinides) that have very similar properties. They are placed below the table to save. Individual Work - Section Review p. 137 questions

3 Valence Electrons Do you remember how to tell the number of valence electrons for elements in the s- and p-blocks? How many valence electrons will the atoms in the d-block (transition metals) and the f-block (inner transition metals) have?. Most have valence electrons, some only have A Different Type of Grouping Besides the 4 blocks of the table, there is another way of classifying elements:,, or. There is a zig-zag or staircase line that divides the table. Metals are on the of the line. Nonmetals are on the of the line. Elements that border the stair case, are the or semi-metals. There is one important exception. is more metallic than not. Metals Metals are (shiny), malleable,, and are good conductors of heat and electricity. They are mostly at room temp.

4 Nonmetals Nonmetals are the. They are dull,, nonconductors (insulators). Some are solid, but many are, and Bromine is a. Metalloids Metalloids, aka semi-metals are just that. They have characteristics of metals and nonmetals. They are but. And they are semiconductors. What is our most important semiconductor?. S-Block Elements Group 1 metals. Soft enough to cut with a. Extremely, found as in nature, stored in in labs to prevent reacting with oxygen. Contains valence electron. Group 2 alkaline metals. than alkali metals. Although abundant, still found as compounds in the Earth s crust. Contains valence electrons. P-Block Elements - 6 Groups - Group 13. Always found with other elements in nature. Contains valence electrons. - Group 14. Contains valence electrons. forms of an element in the same state of matter, but have different physical and chemical properties. Example: and are both made of carbon and are both solids, they differ in their properties because they have different structures they are. - Group 15. Properties vary as in the carbon group. Contains valence electrons. - Group 16. Contain valence electrons. - Group 17. Form compounds with (salts). A salt is a combination of a and a. Contains valence electrons Gases - Group 18. Colorless,, Contains valence electrons except helium which has.

5 d-block Elements Known as metals. Share properties such as, luster, malleability, atomic size,, ionization energy, melting points, and boiling points. Have multiple states. Tend to electrons to become charged ions. f-block Elements: Transition Metals or Rare Metals series. Silvery. Similar reactivity with Group elements. series. elements. Only exist in nature; the rest are elements that are created in accelerators.,,,. There are currently 3 numbering schemes used in chemistry for the ordering of groups. - IA - VIIIA & IB-VIIIB - 1A-2A, 3B-8B, 1B-2B, 3A-8A Individual Practice P. 143 question 1-2 P. 146 question 1-2 P. 149 Q 1 Rows and Periods