Matter

“Food Matters” Is it a Pure Substance or a Mixture? Matter can be divided into two main categories: – Pure substances are homogeneous throughout. They have the same chemical properties no matter where the sample is obtained or how large the sample is. – Mixtures are combinations of two or more substances, with each substance retaining its chemical identity.

“Food Matters” Is it a Pure Substance or a Mixture? Distilled Water – PSCorn Flakes - M Bottled Water – MWhite Vinegar - M Tap Water – MCorn Starch - PS OJ – MPlain Choc - M Milk – MCrunch Bar - M Sugar – PS Salt - PS

Chemistry is the study of … ….Matter Matter is anything that takes up space and has mass. Light and sound are NOT matter!!

MATTER IS MADE UP OF… …Atoms The smallest particle of an element Indivisible ….that guy is Democritus – Greek philosopher – “atomos”

What Does an Atom Look Like? Atoms are too small to see with the eye, but if we could see them, they would look like this…. But we can see GROUPS of atoms.

Groups of Atoms are Called… …Elements …made of IDENTICAL atoms. Examples: Anything on the Periodic Table

Elements can combine to form… …Compounds …contain 2 OR MORE DIFFERENT ELEMENTS (atoms) and are BONDED (attached) or joined in a fixed proportion Compounds are NOT on the Periodic Table; Compounds are NOT MIXTURES (we’ll get to those later…)

Identify these as Element(s) or Compound(s). A B C D

1 Element1 Compound 2 Elements 2 Elements

Classifying Matter All matter is made out of atoms… And all matter can be classified into different categories! – Pure Substances – Mixtures

Mixture MIXTURES CAN BE SEPARATED! Made up of 2 or more elements or compounds – Yellow – an ELEMENT – Red/Blue – a COMPOUND (Atoms are not really colored. The different colors represent different elements.)

Pure Substances (or simply, a substance) CANNOT BE SEPARATED Can be made up of all one element OR all one compound Examples: – table salt – table sugar Element Compound

Identify these as Pure Substances or Mixtures. A B C D

Pure Pure Mixture Mixture 1 element1 compound 2 elements 2 elements

Pure Substances v. Mixtures Video

Mixtures A combination of more than one type of substance The properties of a mixture can vary because the make up of a mixture is not fixed (unlike compounds which have a fixed proportion) 2 Types of Mixtures: – Heterogeneous – the parts of the mixture are noticeably different from one another – Homogeneous – the parts of the mixture are so evenly distributed that it appears to be all the same substance (but a mixture is more than one substance!)

Solutions and Suspensions and Colloids…Oh My! A mixture can be further classified into 3 categories based on the size its largest particles – Solutions – Suspensions – Colloids

Solutions and Suspensions and Colloids…Oh My! Solutions – homogeneous mixtures – Examples: Sugar dissolved in water, tap water – Properties of solutions: DO NOT separate into layers over time If liquid solutions are poured through a filter none of the substance gets trapped in the filter. You can see through liquid solutions – All of these relate to the size of the particles - in a solution, they are tiny!

Homogeneous Mixture Substances are evenly distributed Appears to contain only one substance Solutions – homogeneous mixtures in which one substance dissolves in another

Solutions and Suspensions and Colloids…Oh My! Suspensions – heterogeneous mixtures – Example: sandy water – Properties of solutions: DO separate into layers over time If you pour a suspension through a filter some of the substance in the mixture gets trapped in the filter. Suspensions are cloudy because light gets scattered in all directions as it hits larger particles. – All of these relate to the size of the particles - in a suspension, they are bigger !

Heterogeneous Mixture The parts of the mixture are noticeably different from one another Suspensions – Separate into layers

Heterogeneous Mixture Suspensions can be mixed (“Shake before serving) but eventually separate out.

Solutions and Suspensions and Colloids…Oh My! Colloids– somewhere in between homogeneous and heterogeneous mixtures – Examples: milk and fog – Properties of colloids: DO NOT separate into layers over time. Cannot use a filter to separate the parts of a colloid Light gets scattered when it passes into a colloid – Contain intermediate sized particles

How Do You Separate A Mixture? REMEMBER THE LAB? Here are a few other ways to separate mixtures….

Separation of Mixtures Compounds and mixtures differ in another way. It is difficult to separate a compound into each element. Mixtures can be easy to separate into its components because each component keeps its own properties.

Separation of Mixtures 1.Magnetic attraction: The magnetic components of a mixture can be separated by using a magnet.

Separation of Mixtures 2. Filtration: separates parts of a heterogeneous mixture by pouring it though a filter, the larger particles (residue) will be held in the filter while the smaller ones (filtrate) will pass through.

Separation of Mixtures 3. Distillation: used to separate components of a homogeneous mixture based on their different boiling points. Solution is heated and substance with lower boiling points evaporates and passes through a tube where it cools and turns back into water in another container.

Separation of Mixtures 4. Evaporation: When a mixture contains a solvent such as water and a solute such as salt, the solvent can be allowed to evaporate, leaving behind the solute.

Separation of Mixtures 5. Sedimentation: occurs naturally when solid substances that are heavier than their solvent deposit at the bottom of the mixture.

Separation of Mixtures 6. Decantation: a heterogeneous mixture that has distinct layers can be separated by slowly pouring one of the layers into another container.