1. The Periodic Table Grouping the Elements Section 2 Pages 114 - 120

2. Groups on the Periodic Table Groups, or families, are the vertical columns on the periodic table. The properties of the elements in a group are similar because the atoms of the elements have the same number of electrons in their outer energy level. Atoms often take, give, or share electrons with other atoms in order to have a complete set of electrons in their outer energy level. Elements whose atoms undergo such processes are called reactive and can combine to form compounds. Group Elements react to form compounds

3. Group 1: Alkali Metals Group Contains: metals Electrons in the outer shell: 1 Reactivity: very reactive Other shared properties: softness, silver, shiny, low density Alkali metals are the most reactive metals because their atoms can easily give away the one outer-level electron. Alkali metals are so reactive that in nature they are found only combined with other elements. Alkali metals are soft enough to be cut with a knife. Alkali metals react with water to form hydrogen gas. SodiumPotassium Lithium

4. Group 2: Alkaline Earth Metals Group contains: metals Electrons in the outer shell: 2 Reactivity: very reactive, but less than the alkali metals Other properties: silver, higher density than alkali metals Alkaline Earth Metals are less reactive than the alkali metals. Alkaline Earth Metals have two electrons in their outer shell. It is much harder to give away two electrons when joining with other atoms. Magnesium can be mixed with other metals to make low-density materials for airplanes. Compounds of calcium are found in cement, chalk, and even you!

5. Groups 3 – 12 Transition Metals Group contains: metals Electrons in the outer shell: 1 or 2 Reactivity: less reactive tan alkaline-earth metals Other shared properties: shininess, good conductors of thermal energy and electric current, higher densities and melting points than alkali or alkaline earth metals (except mercury). Groups 3 – 12 do not have individual names, instead they are all called Transition Metals. Transition metals do not give away their electrons as easily at Group 1 or 2 Transition metals are less reactive than alkali metals or alkaline earth metals. Transition metals tend to be shiny and to conduct thermal energy and electric current well.

6. Lanthanides and Actinides Elements in the first row follow lanthanum and are called lanthanides. Lanthanides are shiny, reactive metals. Some of these elements are used to make steel. Elements in the second row follow actinium and are called the actinides. All atoms of actinides are radioactive. Elements listed after plutonium, element 94, do not occur in nature. They are made in laboratories. Very small amounts of americium, element 95, are used in some smoke detectors.

7. Group 13: Boron Group Group contains: one metalloid and five metals Electrons in the outer shell: 3 Reactivity: reactive Other shared properties: solid at room temperature The most common element in the Boron group is aluminum. There is a great amount of aluminum found in the Earth’s crust. Aluminum is an important metal used to make aircraft parts, lightweight car parts, foil, cans, and siding for your house.

8. Group 14: The Carbon Group Group contains: one nonmetal, two metalloids, and three metals Electrons in the outer shell: 4 Reactivity: varies among the elements Other shared properties: solids at room temperature Carbon forms a wide variety of compounds such as proteins, fats, and carbohydrates, necessary for living things on Earth. The metalloids silicon and germanium, are used to make computer chips. Diamonds and soot are both natural forms of carbon. Tin is not very reactive and when combined with iron, it keeps the steel from rusting. Diamonds Soot

9. Group 15: The Nitrogen Group Group contains: two metals, two metalloids, and two metals Electrons in the outer shell: 5 Reactivity: varies among the elements Other shared properties: solids at room temperature (except for nitrogen) Nitrogen, which is a gas at room temperature, makes up about 80% of the air you breathe. Nitrogen can react with hydrogen to make ammonia for fertilizer. Phosphorus is only found in nature combined with other elements Liquid nitrogenred phosphorus

10. Group 16: Oxygen Group Group contains: three metals, one metalloid, and one metal Electrons in the outer shell: 6 Reactivity: reactive Other shared properties: all but oxygen are solid at room temperature Oxygen makes up about 20% of air. Oxygen is necessary for substances to burn. Sulfur, a yellow solid, is used to make sulfuric acid, which is used in chemical industry. Oxygen Sulfur

11. Group 17: Halogens Group contains: nonmetals Electrons in the outer shell: 7 Reactivity: very reactive Other shared properties: poor conductors of electric current; violent reactions with alkali metals to form salts; never found un- combined in nature Halogens are very reactive nonmetals because their atoms need to gain only one electron to have a complete outer level. The atoms of halogens combine readily with other atoms, especially metals, to gain that missing electron. The reaction of a halogen with a metal makes a salt. Chemical properties of the halogens are similar, but their physical properties are very different. Chlorine, a yellowish gas Bromine, a dark reddish liquid Iodine, a dark gray solid

12. Group 18 Noble Gases Group contains: nonmetals Electrons in the outer shell: 8 (except helium which has 2) Reactivity: unreactive Other shared properties: colorless, odorless gases at room temperature. Noble gases are unreactive nonmetals. Noble gases have a full set of electrons in their outer shell so they don’t need to gain or lose electrons. Noble gases do not react with any other elements. Argon is used in light bulbs Helium makes blimps float Neon gases can be used to make neon signs

13. Hydrogen Electrons in the outer shell: 1 Reactivity: reactive Other properties: colorless, odorless gas at room temperature, low density, explosive reactions with oxygen The properties of hydrogen do not match the properties of any single group, so hydrogen is set apart from the other elements in the periodic table. Hydrogen is usually placed above Group 1 because the alkali metals only have one electron in their outer shell. Hydrogen’s physical properties are more like nonmetals than metals. There is more hydrogen in the universe than any other element. Hydrogen is found in the stars. Because of hydrogen’s reactive nature, it is useful as fuel in rockets.