UNIT 2 Classification of matter

An element is a pure substance that is made of one type of atom. Cannot be separated Anything on the Periodic table, only one capital letter! A compound is a pure substance that can be broken down (only by chemical means) into simple stable substances. Each compound is made from the atoms of two or more elements that are chemically bonded (TWO or more capital letters together!) NaCl H 2 O Building Blocks of Matter

Classifying Matter

A pure substance has a fixed composition. compounds and elements. A pure substance differs from a mixture in the following ways: Pure substances have a fixed compostion. Water is always 11.2% hydrogen and 88.8% oxygen by mass. Pure Substances

allotropes  Allotropes: are different forms of the same element (so they are pure substances)  Caused by the conditions in which the element is formed.  C 60

A mixture is a blend of two or more substances and each substance maintains its won properties can be separated phyically Homogeneous mixtures are called solutions uniform in composition (salt-water solution) Solution particles are so small the cannot be seen without a microscope Heterogeneous mixtures not uniform throughout (clay-water mixture) Classification of Matter

Examples of Mixtures

Types of Mixtures

What is an alloy?  An alloy is a solid mixture – usually two metals  Alloys are metal solutions!  Brass, Bronze, sterling silver…

Different karats of Gold 24 karat gold 18 karat gold 14 karat gold Gold Copper Silver 18 / 24 atoms Au 24 / 24 atoms Au 14 / 24 atoms Au

Classification flow chart

Separation of Mixtures Lab Mixture of…. Iron, salt, sand, and poppy seeds Come up with a procedure on how to separate Add plastic spoon to materials If using water, use no more 20 mL

Energy is always involved when physical or chemical changes occur. Law of conservation of mass: In a chemical change, mass is never created or destroyed. Just transformed. Energy, mass and changes