•Anything that has mass and takes up space

•Everything in the universe that you can see is made up of some type of matter

•All matter is made of elements

•A pure substance (only one type of atom/particle) that cannot be separated into simpler substances

http://learn.genetics.utah.edu/content/begin/cells/scale/

•118 in 2012 •98 can be found in nature

•Example: Carbon•All others man-made in a laboratory

•Example: Einsteinium

•Each element is unique, but may share properties with other elements

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•In the 1860s no one had organized the known elements

•A pattern appeared when Dmitri Mendeleev arranged element cards in order of increasing atomic mass

•Elements with similar properties occurred in a repeating pattern

•Metals

•Non-metals

•Metalloids

•Most elements are metals

•Located to the left of the zigzag line

•Most are solid at room temperature

•Located to the right of the zigzag line

•More than half are gases at room temperature

•Border the zigzag line

•Atomic number (top left corner)•Chemical symbol (same worldwide)•Element’s name•Atomic mass (below the element’s name)

•Each row (left to right) is a period. There are 7.

•Each column (top to bottom) is a family/group. There are 18.

•Elements in the same family often have similar properties.