Elements and the Periodic Table

Classification arranging items into groups or categories according to some criteria. act of classifying creates a pattern helps you recognize and understand the behavior of fish, chemicals, or any matter in your surroundings.

Classifying Matter

Matter is usually defined as anything that has mass and occupies space.

Gas Liquid Solid Disorder Some space Order Particles closer together Order Particles fixed in position Total disorder Lots of empty space Gas Liquid Solid

Solids Liquids Gases have a definite volume and shape definite volume, indefinite shape, takes on the shape of the container have no defined shape or volume, will spread until evenly distributed

Mixtures and Pure Substances a combination of two or more substances in which each substance keeps at least some of its original properties.

Heterogeneous mixture . Homogeneous mixture Pure substances has physically distinct parts with different properties, can be recognized by sight. is the same throughout the sample, cannot identify by sight. are substances with a fixed composition

Elements a pure substance which cannot be broken down into anything simpler by either physical or chemical means. simplest form of matter that can exist under normal laboratory conditions.

Elements Science has come along way since Aristotle’s theory of Air, Water, Fire, and Earth. Scientists have identified 90 naturally occurring elements, and created about 28 others. 10

Elements The elements, alone or in combinations, make up our bodies, our world, our sun, and in fact, the entire universe. 11

The most abundant element in the earth’s crust is oxygen. 12

Compound a pure substance that can be decomposed by a chemical change into simpler substances with a fixed mass ratio.

Sugar (A) is a compound that can be easily decomposed to simpler substances by heating. (B) One of the simpler substances is the black element carbon, which cannot be further decomposed by chemical or physical means.

The Periodic Table and the Elements What is the periodic table ? What information is obtained from the table ?

Charge (if ion) Atomic Mass Symbol Atomic Number

Hydrogen Protons: 1 Neutrons: 0 Electrons: 1 H 1 1

Sodium Protons: 11 Neutrons: 12 Electrons: 11 Na 23 11

Dmitri Mendeleev (1869) In 1869 Mendeleev and Lothar Meyer (Germany) published nearly identical classification schemes for elements known to date. The periodic table is base on the similarity of properties and reactivities exhibited by certain elements. Later, Henri Moseley ( England,1887-1915) established that each elements has a unique atomic number, which is how the current periodic table is organized. http://www.chem.msu.su/eng/misc/mendeleev/welcome.html

Coloring the Periodic Table Families Mrs. LaRosa Some images are from www.chem4kids.com www.middleschoolscience.com 2008 21

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Metal Non-Metal Elements that are usually solids at room temperature. Most elements are metals Elements in the upper right corner of the periodic table. Their chemical and physical properties are different from metals.

Metalloid Elements that lie on a diagonal line between the metals and non-metals. Their chemical and physical properties are intermediate between the two.

Properties of Metals Metals are good conductors of heat and electricity. Metals are shiny. Metals are ductile (can be stretched into thin wires). Metals are malleable (can be pounded into thin sheets). A chemical property of metal is its reaction with water which results in corrosion. 25

Properties of Non-Metals Non-metals are poor conductors of heat and electricity. Non-metals are not ductile or malleable. Solid non-metals are brittle and break easily. They are dull. Many non-metals are gases. Sulfur 26

Properties of Metalloids Metalloids (metal-like) have properties of both metals and non-metals. They are solids that can be shiny or dull. They conduct heat and electricity better than non-metals but not as well as metals. They are ductile and malleable. Silicon 27

Families on the Periodic Table Elements on the periodic table can be grouped into families bases on their chemical properties. Each family has a specific name to differentiate it from the other families in the periodic table. Elements in each family react differently with other elements. 28

The periodic table is made up of rows of elements and columns. An element is identified by its chemical symbol. The number above the symbol is the atomic number The number below the symbol is the rounded atomic weight of the element. A row is called a period A column is called a group

Key to the Periodic Table Elements are organized on the table according to their atomic number, usually found near the top of the square. The atomic number refers to how many protons an atom of that element has. For instance, hydrogen has 1 proton, so it’s atomic number is 1. The atomic number is unique to that element. No two elements have the same atomic number. 30

What’s in a square? Different periodic tables can include various bits of information, but usually: atomic number symbol atomic mass number of valence electrons state of matter at room temperature. 31

Common Elements and Symbols 32