Elements Compounds and Mixtures Elements and Compounds Element

Elements, Compounds and Mixtures

Elements and Compounds • Element – a substance that contains only one kind of atom. • Compound – a substance that contains atoms of more than one kind joined together. • Mixtures – contains different types of particles that are not joined together.

Elements - Atoms and their Symbols • There about 90 different types of atoms that occur naturally on earth. • There a few more that can be made by nuclear reactions making about 100 elements in all. – The latest man made element is Uuo. Made by firing lead atoms at Krypton atoms. Only 3 atoms of ununoctium were made and they lasted less than a millisecond.

Atoms and their Symbols • Every atom has its own symbol; – – C carbon Co cobolt Ca calcium Cl Chlorine • The names may vary in different languages, but the chemical symbol in always the same.

Common Elements • The particles in most elements are individual atoms, but in some elements the particles are molecules; Name Symbol Argon Diagram Formula Description Ar Ar atoms Iron Fe Fe atoms Oxygen O O 2 Molecule (each with 2 atoms)

Mixtures and Compounds • Hydrogen and oxygen are elements. • If you put them together you have a mixture of elements. • If a flame is put in the mixture a chemical reaction takes place and a new substance is formed – a compound. • Hydrogen + oxygen water

Compounds • There are over 20 million known compounds. • When a new compound is formed the properties are different from the elements that formed it. • Sodium + • Very reactive Chlorine poisonous sodium chloride salt