Elements, Compounds and Mixtures

Pure Substances: Elements and Compounds

Heterogeneous Mixture Classification of Matter Chart Matter Mixture Pure Substance Homogeneous Mixture Element Compound Heterogeneous Mixture

Pure Substance Substance made of one material and has definite properties Particles of a substance are all alike Same throughout

Elements Simplest form of a pure substance Compound Elements Pure Substance Simplest form of a pure substance Cannot be changed into a simpler substance by any chemical process Found on periodic table

Elements Atom Smallest particle of an element Compound Elements Pure Substance Atom Smallest particle of an element Basic building block of matter

Compound Pure substances made of more than one element 2 or more elements chemically combined

Two Elements Combine to form… Sodium: extremely explosive when it comes in contact with water Chlorine: a poisonous gas Combine to form…

… Sodium Chloride Salt!  We put it on our french fries!

Compound Compounds are made of molecules Pure Substance Element Compound Compounds are made of molecules Molecule: two or more atoms bonded together Every water molecule is exactly the same 2 Hydrogens bonded to 1 Oxygen

Compounds … continued Not always 2 different atoms bonded together Oxygen = element Oxygen that we breathe is a molecule O2

Mixture Matter that consists of two or more substances mixed together, but NOT chemically combined Substances that make up a mixture can be present in varying quantities Can be separated by physical means Methods used to separate a mixture are based on the properties of its components

Types of Mixtures

Heterogeneous Mixture A mixture that does NOT appear to be the same throughout “least mixed” of all mixtures

Homogeneous Mixtures A mixture that appears to be the same throughout “Well mixed” mixture Does NOT separate upon standing

Colloid A homogeneous-looking mixture in which the particles are mixed together, but NOT dissolved Has some characteristics of homogeneous mixtures (particles are evenly spread throughout) and some characteristics of heterogeneous mixtures (particles are not actually dissolved)

Colloid (refer to fig 4-9 on p. 92) Actually falls somewhere between a solution (homogeneous mixture) and a suspension (heterogeneous mixture) Particles are kept permanently suspended Particles are relatively large Will NOT separate upon standing Examples: mayonnaise, toothpaste, milk, fog

Alloys Homogeneous solutions of metals Solid Solution Often used in jewelry Example – brass: alloy of copper and zinc, Gold jewelry is an alloy of gold and copper

Solution Homogeneous mixture of two or more substances “best mixed” mixture Composed of solute and solvent

Solute Substance that is dissolved Substance that there is less of Example: salt is the solute in salt water solution

Solvent Substance that does the dissolving Substance that there is more of Example: water is the solvent in salt water solution Since water is used as the solvent most often, it is called the “universal solvent”

Characteristics of a Solution Composed of a solvent and solute Particles are NOT large enough to be seen Does NOT scatter light Properties are evenly spread out (for example: color, taste, odor, etc.) Types of solutions: Fig. 4-12, p. 94

Properties of Elements, Compounds and Mixtures Made up of only one kind of atom Made up for more than one atom Made up of more than one kind of molecule Cannot be broken down by chemical means Can be broken down by chemical means Can be separated by physical means Has the same properties as the atoms making it up Has different properties from the elements making it up Has same properties as the substances making it up Has the same properties throughout Has different properties throughout  

Identify the following with as many terms as apply: Table Salt Brass Iron Trail Mix Gold Water Sugar Mayonnaise Fog Tacos Homogeneous Mixture Element Heterogeneous Mixture Compound Colloid Alloy Solution

Answers Table Salt – compound Brass – homogeneous mixture, alloy Iron – element Trail Mix – heterogeneous mixture Gold – element Water – compound Sugar – compound Mayonnaise – homogeneous mixture, colloid Fog – homogeneous mixture, colloid Tacos – heterogeneous mixture