Periodic Table

1. Periodic Table • Elements • A pure substance that cannot be broken down into simpler substance by chemical mean • Scientists have discovered about 117 elements • About 90 of these elements are found in nature, the rest are synthetic, which means they are man made

2. Periodic Table • Dmitri Mendeleev gave us a functional way to classify elements. • Mendeleev’s design was based on chemical properties of the elements. • It was noticed that the chemical properties of elements increased in a periodic manner. • The periodicity of the elements was demonstrated by Mendeleev when he used the table to predict occurrence and chemical properties of elements which had not yet been discovered.

3. Periodic Table Mendeleev left blank spaces in his table when the properties of the elements above and below did not seem to match. The existence of unknown elements was predicted by Mendeleev on the basis of the blank spaces. When the unknown elements were discovered, it was found that Mendeleev had closely predicted the properties of the elements as well as their discovery.

4. The Periodic Table • A map of the building block of matter. http://www.chemsoc.org/viselements/pages/periodic_table.html

5. Describe How To Read The Periodic Table

6. Describe how to read the periodic table: • Every table has:

7. Describe how to read the periodic table: Atomic Number The number of protons in an atom identifies the element. The number of protons in an atom is referred to as the atomic number of that element.

8. Describe how to read the periodic table: Atomic Symbol:The atomic symbol is one or two letters chosen to represent an element ("H" for "hydrogen," etc.). These symbols are used everywhere in the world Usually, a symbol is the abbreviation of the element or the abbreviated Latin name of the element.

9. Describe how to read the periodic table: Atomic Mass:The atomic mass is the average mass of an element in atomic mass units ("amu"). Though individual atoms always have a whole number of amus, the atomic mass on the periodic table is shown as a decimal number because it is an average of all the isotopes of an element.

10. Periods and Groups Horizontal rows in the periodic table are called periods numbered from 1 -7. Elements in periods are arranged in order of increasing atomic number (number of protons).

11. Periods and Groups • Vertical columns are called groups (or families) • Elements can be arranged in this fashion based on the arrangements of the electrons outside the nucleus

13. Periods and Groups Sizes of the atoms decrease as we move from left to right across a period

15. Periods and Groups All the elements in a column have remarkably similar chemical properties Some of the columns (groups) have been given special names “families” to distinguish them

16. Periods and Groups • Four chemical families of the periodic table: • alkali metals (IA) • alkaline earth metals (IIA) • halogens (VII) • noble gases (VIIIA).

17. Periods and Groups • Alkali Metals • These are the metals in the first column of the periodic table. They are soft shiny metals that usually combine with group VIIA nonmetals in chemical compounds in a 1:1 ratio. • Alkaline Earth Metals • These are the elements in the second column of the periodic table, and they are very similar to the alkali metals. They combine with the group VIIA nonmetals in a 1:2 ratio. they are reactive, but not as reactive as Group IA.

18. Periods and Groups • Halogens • The halogens are found in group VIIA. They are fluorine, chlorine, bromine, and iodine. The halogens exist as diatomic molecules in nature. They are very reactive. • Noble Gases • The noble gases are also called rare gas elements, and they all occur in nature as gases. The noble gases make up the group VIIIA which is the last column in the periodic table. The noble gases fulfill the octet rule by having a full outer level with 8 valence electrons. Therefore, they do not undergo chemical reactions because they do not accept any electrons. They are almost non reactive.

19. Reading the Periodic Table: Classification • Nonmetals, Metals, Metalloids, Noble gases

20. Metals • Metals makeup more than 75% of the elements in the periodic table. Metals are characterized by the following physical properties. • 1. They have metallic shine or luster.2. They are usually solids at room temperature.3. They are malleable. Malleable means that metals can be hammered, pounded, or pressed into different shapes without breaking. 4. They are ductile meaning that they can be drawn into thin sheets or wires without breaking. 5. They are good conductors of heat and electricity.

21. Nonmetals • There are 17 nonmetals in the periodic table, and they are characterized by four major physical properties. • 1. They rarely have metallic luster.2. They are usually gases at room temperature.3. Nonmetallic solids are neither malleable nor ductile. 4. They are poor conductors of heat and electricity.

22. Metalloids • The six metalloids are B, Si, Ge, As, Sb, and Te. The properties of the metalloids have characteristics in between that of the metals and the nonmetals. They are good conductors of heat and electricity, but they are not good conductors or insulators.

23. Summary of Trend 3. Ionization Energy: Largest toward NE of PT 4. Electron Affinity: Most favorable NE of PT • Periodic Table and Periodic Trends • 1. Electron Configuration 2. Atomic Radius: Largest toward SW corner of PT

24. Summary • Periodic Table: Map of the Building blocks of matter • Type: Metal, metalloid and Nonmetal • Family: Elements in the same column have similar chemical properties because of similar valence electrons Alkali, Alkaline, halogens, noble gases • Period: Elements in the same row have valence electrons in the same shell.