Matter: Compounds and Mixtures Chapter 4 Section 1

Let’s Review: Matter is anything that has a mass and takes up space (has a volume). Matter is made of atoms. Matter can be either a pure substance, like an element or compound, or a mixture. Matter has both physical properties and chemical properties that tell us about the substance.

Compounds Compounds are substances made of 2 or more elements that form a molecule. Molecule - 2 or more atoms bonded together Examples of common compounds: Table Salt - NaCl Oxygen gas – O2 Water – H2O

Properties of Compounds The chemical and physical properties of the compound are DIFFERENT from the properties of the elements that make it up. Example: + = Sodium + Chlorine gas = Table Salt (Na+) (Cl-) (NaCl) Metallic Solid Gas Solid Shiny Yellow White and Dull Reactive Reactive Non-reactive

Properties of Compounds Continued… Compounds have BONDS between the atoms It is difficult to separate the parts of a compound because the bonds are not easily broken. Compounds have chemical formulas to tell you what elements are found in the compound and how many atoms of each element are present. The chemical formula for water is H2O. There are two atoms of hydrogen and one of oxygen. If there is 1 atom present, no number is written, but if there are 2 or more atoms present a number is written as a subscript.

Kinds of Compounds Compounds can be ionic or covalent Ionic compounds form by giving away/taking electrons Covalent compounds form by sharing electrons

Mixtures Mixtures are combinations of 2 or more pure substances or compounds not bonded together Some common mixtures: Iced Tea Dirt Paint

Properties of Mixtures The chemical and physical properties of a mixture are SIMILAR to the properties of the substances that make it up. EXAMPLE + = Sugar + Water = Sweetened Water Crystals Liquid Liquid Sweet Not sweet Sweet

Properties of Mixtures Continued… There are NO BONDS holding mixtures together. Mixtures can often be separated easily. Mixtures can occur in any proportions and DO NOT HAVE A SET FORMULA.

Kinds of Mixtures A homogeneous mixture is mixed EVENLY: water & food coloring Kool Aid mix & water A heterogeneous mixture is mixed UNEVENLY oil & water sand & rocks.