1. Arranging the Elements Chapter 5 Section 1 p. 106 - 113 Vocabulary 1.periodic 2.periodic table 3.period 4.group

2. Once scientists discovered a number of elements, they wanted to share their information with other scientists, but there was no organized format set up. Some scientists made their own symbols or they communicated in foreign languages. They needed someone to bring everything together. Dmitri Mendeleev was a Russian chemist who discovered a pattern to the elements in 1869. He arranged the elements in order of increasing atomic mass. He saw that the elements occurred in a repeating pattern. There were gaps in the patterns, and he was able to predict the properties of elements that hadn’t even been discovered yet!! Discovering a Pattern

3. Changing the Arrangement In 1914, Henry Moseley, a British scientist, changed the arrangement of the Periodic Table. He arranged the table according to the elements’ increasing atomic number. The periodic law states that the repeating chemical and physical properties of elements change periodically with the elements’ atomic number.

4. Rows are called Periods Columns are called groups or families Some element names come from Greek or Latin. The first letter of an element’s name is always capitalized and the second letter is always lower case. The Lanthanide Series and the Actinide Series fit into the last two rows. They are placed below the table in order to make the table fit onto one page. * *

5. Decoding the Periodic Table Each square on the periodic table includes the element’s name, symbol, atomic number, and atomic mass. Element names can come from Greek or Latin, or they can be named after people or places. Element symbols can be one or two letters long. If it is one letter, the letter is always capitalized. If it is two letters long, the first letter is capitalized and the second letter is lower case. Horizontal rows are called periods. The physical and chemical properties of elements follow a repeating pattern as you move across the period. Properties such as conductivity and reactivity change gradually from left to right in each period. Each vertical column of elements is called a group or family. Elements in the Same group often have similar chemical and physical properties. Periods and Groups on the Periodic Table

6. The Periodic Table and Classes of Elements Elements are classified as metals, nonmetals, and metalloids, according to their properties. The number of electrons in the outer energy level of an atom is one characteristic that helps determine which category an element belongs in.

7. Metals Most elements are metals. Metals are found to the left of the zigzag line on the periodic table. Atoms of most metals have few electrons in their outer energy level. Most metals are solid at room temperature (except mercury) Properties of Metals Metals tend to be shiny. Most metals are ductile. They are good conductors of electricity and thermal energy (heat). Most metals are malleable.

8. Nonmetals Nonmetals are found to the right of the zigzag line on the periodic table. Atoms of most nonmetals have an almost complete set of electrons in their outer level. More than half of the nonmetals are gases at room temperature. Many properties of nonmetals are the opposite of the properties of metals. Properties of Nonmetals Nonmetals are not malleable or ductile. Some are brittle and will break or shatter when hit with a hammer. The are not shiny. They are poor conductors or electricity and thermal energy.

9. Metalloids Metalloids are also called semiconductors. They are the elements that border the zigzag line on the periodic table. Atoms of metalloids have about half of a complete set of electrons in their outer energy level. They have some properties of metals and some properties of nonmetals. Properties of Metalloids Metalloids can be shiny, brittle, and easily smashed into a powder. They can also be hard. At high temperatures, they can also be good conductors of electric current. Tellurium is shiny, but can be brittle and easily smashed into a powder. Boron is almost as hard as a diamond, but is also brittle. At high temperatures, it is a good conductor of electric current.

10. The Element Song

11. Quiz Time! 1.How had Mendeleev arranged the elements when he discovered a pattern? according to increasing atomic mass 2. How are elements in the periodic table arranged today? according to increasing atomic number 3. What is the difference between a period and a group on the periodic table? a period is horizontal and a group is vertical 4. What are four properties shared by most metals? solid at room temperature, ductile, malleable and shiny

12. 5. Which elements are in the same group as oxygen? sulfur, selenium, tellurium, and polonium