Elements, Compunds & Mixtures

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Elements, Compunds & Mixtures

Elements

Scientists have organised all the discovered elements into a tale called the Periodic Table

Non Metals -usually dull -Mostly liquid or gas, some are solids -Brittle for solids -Low density -Low melting and boiling points -Poor ability to conduct electricity and heat

Metals- shiny, can be polished -solids -Mallaeble & ductile -High density -High melting and boiling points -Good ability to conduct electricity and heat

An element is a substance which cannot be broken down into two or more simpler substances by chemicla methods

Mixtures

Properties of Mixtures: -when a mixture is formed, no chemical reacttion occurs -a mixture has the properties of its constituent substances -a mixture can br separated easily by physical methods(ie with out involving chemical reaction -the components in mixturres are not mixed in any fixed proportion

A mixture consists of two or more different substances that are mixed but not chemically commbined together

Compounds

Compounds can be broken down by: -heating -passing electric current -when exposed to light

Decompositon occurs when more complex compounds are heated to break them down into simpler compounds

Certain elements and/or compounds can combine to form new compounds when they are in contact with one another

A compound is a substance which is made up of two or more different elements chemically combined together.

Elements or compounds burn adn combine with oxygen to form one or more new compounds

Its constituent elements are always combined in a fixed proportion by mass

The properties of a compound are usually different from its constituent elements