Elements and Compounds Pure Substances Elements and Compounds

Opening Assignment Physical (P) or Chemical property(C)? 1. dissolving sugar in water (solubility) 2. blue color 3. ability to rust 4. melting point 5. reacts with water to form a gas 6. flammability

What is matter and how do we describe it? All matter is made up of Elements An element is a pure substance….. Can’t be broken down into another substance.

Examples of elements

What are elements? They are the simplest substances There are 92 naturally occurring types of elements. The smallest atom, and one of the lightest substances, is HYDROGEN. The biggest atom (and one of the heaviest substances) is URANIUM. Each of the elements has its own symbol; for example: hydrogen's is H, uranium is U, gold is Au, oxygen is O, copper is Cu ...

Atoms Elements are made up one type of atom An atom is a basic particle -- building blocks

Molecules Atoms combine to form molecules Molecules are larger particles made up of 2 or more atoms held together with chemical bonds

Chemical bond Chemical bond is an attraction between two atoms

Molecules Atoms combine to form larger particles called molecules

Sugar molecule – 3 different types of atoms stuck together in a pattern

Sugar The substance sugar is just a collection of many sugar molecules

Salt Molecule/Substance salt

Modeling Molecules Different colored spheres stand for different atoms

Carbon Dioxide CO2

Methane CH4

Rust The chemical formula for rust is Fe2O3 How many Fe atoms are there and how many oxygen atoms are there in this compound?

Compounds 'A Compound is a pure substance made of 2 or more elements chemically combined O2 is molecule ….but it is not a compound! You need 2 different elements to form a compound.

Other things about compounds A compound cannot be separated into different substances by mechanical means When elements combine they form compounds with new physical and chemical properties.

Which of these molecules are also compounds?