Substances, Compounds & Mixtures How everything is put together.

Substances  Matter that has the same composition and properties throughout is called a substance. When different elements combine, other substances are formed.

Substances  Contains only one particle  Can exist in 3 states of matter  Can be elements or compounds Picture from

Elements  An element is a pure substance (only 1 type of particle) that cannot be separated into simpler substances by physical or chemical means. 

Element

Compounds  A compound is a pure substance composed of 2 or more elements that are chemically combined.

Examples of Compounds Sodium (Na) + Chlorine (Cl) NaCl Hydrogen (H) + Oxygen (O) H 2 O Carbon (C) + Oxygen (O) CO 2 Compounds contain elements The elements combine + lose their original properties Compounds CAN be separated by chemical means The elements combine in specific ratios Compounds contain elements The elements combine + lose their original properties Compounds CAN be separated by chemical means The elements combine in specific ratios

 Look at the pictures below - is it an element or a compound? Element or compound? ElementCompoundElement Compound

 H 2 0 is the chemical formula for water, and H 2 O 2 is the formula for hydrogen peroxide.  The formula tells you which elements make up a compound as well as how many atoms of each element are present. Compounds Have Formulas

How to read a formula H20H20H20H20 This is a subscript. It tells us how many atoms of that element exist in one unit of that compound. Hydrogen is made of 2 H atoms and 1 O atom. No subscript is used when only one atom of an element is present.

Let ’ s try it…  Using your white board tell how many atoms there are in each element.  Sulfuric AcidH 2 SO 4  2 Hydrogen  4 Oxygen  Hydrogen Peroxide H 2 O 2  2 Hydrogen  2 Oxygen

And some more formulas…  Carbon Dioxide CO 2  1 Carbon  2 Oxygen  Carbon Monoxide CO  1 Carbon  1 Oxygen  Calcium Carbonate (Found in shells, eggshells, antacid) CaCO 3  1 Calcium  1 Carbon  3 Oxygen

Compound Review  A pure compound has the same elements and the same amount of elements all of the time  Elements are chemically combined  Compound properties are different from the properties of the elements  They cannot be separated physically  Physical properties such as boiling point or melting point of pure substances are do not change

 Look at the pictures below - is it an element or a compound? Element or compound? ElementCompoundElement Compound

 How about this - element or compound? Element or compound? Actually this is neither an element or a compound - it is a mixture!

 How can we describe a mixture?  Remember: an element is made up of just one type of atom  A compound is two or more elements which are chemically bound together…  A mixture is made from different substances which are not chemically bound Mixture

 Imagine coloured sweets which can be mixed together in a packet, but are not chemically joined together Sweets MixtureElement 1Element 2Element 3Element 4 You could easily separate these into their different colours - without needing a chemical reaction…

 A mixture is made from different substances, which are not chemically bound  E.g. air is a mixture of gases  The gases (oxygen; nitrogen; argon; and carbon dioxide) can be easily separated  The properties of the mixture are just a mixture of the properties of the separate parts!!! Definition

Mixtures  A mixture is a combination of 2 or more substances that are not chemically combined.

Examples of Mixtures chicken noodle soup pizza – yes, that would be Yoda… salad Properties of Mixtures: Each substance in a mixture keeps its identity You can physically separate them They also contain elements, compounds, or both And they can be formed using any ratio of components

Mixtures may be homogeneous or heterogeneous  The prefix “homo” indicates the same  Homogeneous mixtures have the same appearance and properties throughout the mixture  The prefix “hetero” indicates difference  Heterogeneous mixtures consist of visibly different substances

Mixtures  A mixture is a combination of two or more substances where there is no chemical combination or reaction.

Which one is the pure substance?

Solids, liquids and gases can be combined to create a mixture.

Types of Mixtures  There are THREE types of mixtures:  Solutions  Suspensions  Colloids

Solutions  A solution is a mixture that appears to be a single substance, but it is actually composed of 2 or more substances that are distributed evenly amongst each other.  SOLUTIONS ARE HOMOGENEOUS carbon dioxide is dissolved in water sugar & Kool-Aid powder are dissolved in water salt is dissolved in water

Heterogeneous Mixtures:  The prefix: "hetero"- indicates difference  A heterogeneous mixture consists of visibly different substances or phases  Two or more parts can be seen

Examples:  Pizza  Sandwich  Chex Mix

Suspensions  A suspension is a mixture in which particles of a material are dispersed throughout a liquid or gas, but are large enough that they settle out.  SUSPENSIONS ARE HETEROGENEOUS That water is disgusting! Italian dressingmuddy water

Colloids  A colloid is a mixture in which the particles are dispersed throughout but are not heavy enough to settle out.  COLLOIDS ARE HOMOGENEOUS milkmayonnaise Colloids have properties of both solutions & suspensions.

E.g. a mixture of iron powder and sulphur powder will show properties of both iron and sulphur! This means our mixture will contain grey magnetic bits of iron + yellow bits of sulphur Mixture Example

 Look at the following - copy down the particle boxes, and decide if it represents an element, compound or mixture Examples ElementCompoundElementMixture

An element contains just one type of atom A compound contains two or more types of atoms that are chemically bound A mixture contains two or more different substances, that are not chemically bound The different substances in a mixture can be elements or compounds Summary

Compounds vs Mixtures Compounds Mixtures Combine chemically forming molecules Not chemically combined Combine in set proportions Can combine in any proportion Separated chemically Separated physically

Comparing Elements, Compounds & Mixtures ElementsCompoundsMixtures What are they made up of? Can they be broken down? If yes, how? Do they keep or lose their original properties? Draw what the particles look like.

Identify the following with as many terms as apply 1.Table salt 2.Salad 3.Mayonnaise 4.Italian dressing 5.Pepsi 6.Oxygen 7.Hydrogen 8.Water Mixture Element Compound Suspension Colloid Solution Homogeneous Heterogeneous