Concept: Structure of Matter

Bell Work 09/19/2012 Write question and answer. Can you chemically break down an atom? Why or why not? Too much energy is required to break an atom down into its protons, neutrons, and electrons alone. It would require a nuclear reaction to do this.

Bell Work 09/20/2012 Write question and answer. Explain why is it easier to separate a heterogeneous mixture than a homogeneous mixture? In a heterogeneous mixture, you can identify the components of the mixture

 Vocabulary Write word and definition. Underline and highlight vocabulary word. Write word on front and definition on back of index cards. Create a poem or rap of vocabulary words and definitions. Create foldable with words and definitions. Create a crossword puzzle using words and definitions. Also make answer key!!!  Atom  Element  Compound  Pure substance  Mixture  Heterogeneous  Homogeneous  Solution  Solute  Solvent  Concentration

 What are atoms?  The smallest unit of an element that maintains the chemical properties of that element

 What is matter?  Anything with mass and volume (or takes up space)  Matter can be broken into two categories Pure Substances (1 st ) Mixtures

 Pure Substances  Fixed, definite composition/uniform/unchanging  Pure substances can be broken down further into two more categories: elements and compounds

 Elements  A substance that cannot be separated or broken down into simpler substances by chemical means  Found on periodic table

 Compounds  2+ atoms chemically bound  Must break bonds to get elemental form  May form molecules Water Carbon dioxide  Law of Definite Proportions The law that states that a chemical compound always contains the same elements in exactly the same proportions by weight or mass

 Mixtures  Contains 2+ kinds of matter physically mixed  Can be physically separated  Broken down into 2 main groups Homogeneous Heterogeneous

Homogeneous Mixtures Looks pure b/c evenly/uniformly mixed Also called a solution  Solid in liquid (salt water)  Gas in liquid  Solid in solid  Alloys-mixture of 2+ metals  Solid at room temperature

solutions  Solute – substance being dissolved (sugar)  Solvent – substance doing the dissolving (water) RULE OF THUMB!!! USUALLY YOU WILL HAVE MORE SOLVENT THAN SOLUTE!!! What is solubility?  Amount of solute that can be dissolved  Concentration – high C – high solute/solvent, low C – low solute/solvent

Heterogeneous Looks impure Substances can be identified Not uniform throughout b/c unevenly mixed Examples: granite, wood, blood Also called suspensions  Visible particles settle

Colloids Ex. Milk, fog, clay Look like a solution b/c particles do not settle, but acts like a suspension b/c particles do not dissolve How can you tell if it is a colloid?  Tyndall effect – scattering of light by particles in a mixture

Solution Colloid Suspensio n Does it settle? No yes Can it be filtered? No Yes Does it scatter light? NoYes

Bell Work Write Question and Answer How can you tell a solution, suspension, and colloid apart from one another? Differentiate between the 3.

Bell Work Write Question and Answer How can you tell a solution, suspension, and colloid apart from one another? Differentiate between the 3. Solution is a homogeneous mixture where particles are uniform throughout and does not settle. Suspensions are heterogeneous mixtures that have particles that settle and it is not uniform throughout. Colloids fall in between solutions and suspensions in that it has particles that do not settle (like solutions); but, the particles do not dissolve (like in suspensions). You can also use the Tyndall effect to differentiate colloids from solutions because colloids will scatter the light.

Methods for separating mixtures Distillation Filtration Chromatography

Distillation Separating mixture by using differences in boiling points Good for separating solutions How? Heat mixture to the b.p. of the substance with the lowest b.p. This will create a vapor first. Collect and condense into a liquid in a separate container. Continue process if solution contains more than 2 substances.

Filtration Separating solid from liquid (and solid from solid; sieving) Use porous barrier to separate

Chromatography Separation technique that identifies parts of a mixture by how fast compounds move across a material Greatest attraction moves the fastest

Write question and answer. Explain how you could separate sand and salt. You could first add water to the solid mixture to form salt water. Filter the salt water from the sand. This will leave sand in the filter and salt water in the container. Then, through distillation process, heat the salt water to the water’s boiling point so that you can collect and condense water vapor in separate container leaving only salt behind.

Write Questions and Answer Pg. 14 # 4 Pg. 23 #’s 23, 25, 27 Pg. 25 #’s 3-6, 8, 10