Classifying Elements There are 3 main categories in which Scientists classify all elements: Metals Nonmetals Metalloids

Metals How would you define what a metal is? Besides silver, copper, gold, etc., calcium, sodium and potassium are considered metals. Of the 117 known elements, most are metals. If you look at the periodic table, you will see a dark zigzag line. The elements to the left of this line are metals or metallic elements.

Properties of Metals Chemical Properties Chemical properties of any element depend the electron arrangement of the atoms Specifically the number of electrons in the outermost energy level: valence electrons. Metals tend to lose their valence electrons when they combine chemically. Corrosion occurs to many metals Corrosion is the gradual wearing way of a metal due to a chemical reaction in which the metal element is changed is not a metallic compound. Rusting or tarnishing

Nonmetals Nonmetals are located to the right of the zigzag line. Nonmetals tend to have the opposite physical and chemical properties of metals. Physical Properties No luster, or dull Don’t conduct heat and electricity well. Not ductile or malleable Lower densities and melting points

Chemical properties Nonmetals tend to gain valence electrons during chemical bonding. Elements with 8 valence electrons do not react with other elements

Metalloids The dividing line between metals and nonmetals is not as definite as it appears. For the elements along the dark zigzag line have properties of both metals and nonmetals. These elements are called metalloids

Properties Conduct heat and electricity, but not as well as metals Ductile and malleable

Alkali Metals Remember: Elements within the same family of the periodic table have similar properties because they have the same number of valence electrons. Family 1, with the exception of hydrogen are called the alkali metals. Alkali Metals have 1 valence electron Lithium Sodium Potassium Rubidium Cesium Francium

Lithium

Sodium

Alkali metals are soft, sliver-white, shiny metals. Good conductors of heat and electricity Since they have only 1 valence electron, they bond readily with other substances So reactive they are never found uncombined in nature.

React Violently with Water Hydrogen and extreme heat is produced Cesium

Common uses of Alkali Metals: Sodium used in table salt and Baking Soda Potassium used as a mineral Lithium used a chemical imbalance stabilizer

Alkaline Earth Metals Family 2 is known as the Alkaline Earth Metals Never found in nature uncombined. They have 2 valence electrons They lose their valence electrons easily to bond with other substances (not as easily as Alkali metals). Not as reactive as Alkali metals They are: Beryllium Magnesium Calcium Strontium Barium Radium

These elements give characteristic colors when heated in a flame: Mg: brilliant white Ca: brick-red Sr: crimson Ba: apple green

Magnesium: combined with aluminium to make alloys that are strong yet light weight. Used in fireworks and medicine

Calcium: abundant in the Earth’s crust, and they make up limestone and marble rock. In your teeth and bones

Transition metals are in the middle of the periodic table. With the exception of mercury, transition metals are harder, more dense, and have higher melting points than alkali metals and alkaline-earth metals. They are also less reactive, but they can form positive ions.