Transcript Presentation

Elements
It's Elementary
-an element is a pure substance that cannot be separated into
simpler substances by physical or chemical means
-pure substance means that there is only one type of particle
present
-elements contain only one type of particle (called an atom)
-atoms of a pure substance are alike for that substance
no matter where it comes from
EXAMPLE:
Oxygen is oxygen, whether it comes from the
atmosphere, the ocean, or Earth's crust
Single Oxygen
atom
Di-oxygen (O2)
molecule
Ozone (O3)
molecule
Properties of Elements
-each element has its own set of characteristic properties
-do not depend on size of sample
-can be used to identify element
EXAMPLES:
physical propertiesboiling point, melting point, density, color,
texture, hardness
chemical propertiesreactivity, flammability
WHY IS KNOWING THESE PROPERTIES FOR
DIFFERENT ELEMENTS HELPFUL IN IDENTIFYING
THEM?
Classification of Elements
-many elements share similar properties
-classified into groups according to those properties
-3 major categories of elements:
Metals, Metalloids, & Nonmetals
-some properties of unfamiliar elements can be
predicted simply by knowing the category to which
they belong
EXAMPLE:
Cobalt, iron, and nickel are metals. If a particular element is
classified as a metal, it shares certain properties with all
other metals.
Silicon
Gallium
Iodine
Metals
-shiny
-good conductors of electric current & thermal energy
-malleable
-ductile
-used in construction of:
buildings, automobiles, & aircraft or to make wire,
coins, or jewelry
EXAMPLES:
Lead (Pb)
Gold (Au)
Copper (Cu)
Tin (Sn)
Metalloids
-also called semiconductors
-have properties of metals and nonmetals
-some are shiny, some are dull
-somewhat malleable & ductile
-some conduct thermal energy & electric current well
-silicon is a metalloid used in making computer chips
EXAMPLES:
Boron (B)
Silicon (Si)
Antimony (Sb)
Nonmetals
-dull (not shiny)
-poor conductors of thermal energy & electric current
-solids brittle & un-malleable
-few familiar objects are made from only nonmetals
-neon gas used in signs and graphite (carbon)
used in pencils are nonmetals
EXAMPLES:
Neon (Ne)
Sulfur (S)
Bromine (Br)
Graphite
(Carbon - C)