Mixtures - Another way to describe matter Other ways:
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1 Classifying Matter According to its Composition Mixtures Elements & Compounds
2 Mixtures - Another way to describe matter Other ways: Physical stateChemical and physical propertiesDensity
3 Composition of Matter Matter Pure substance Mixture Element Compound Which can exist asPure substanceMixtureElementCompoundHomogeneousHeterogeneous
4 Pure Substance = sample of matter with only one component Elements = pure substances that cannot be broken down into simper substances with different propertiesCompounds = a pure substance made up of two or more elements that are chemically combined in a fixed proportion by mass
5 Mixtures= a combination of two or more substances in which each retains its own identityMay be a homogenous mixtureOR- May be a heterogeneous mixture
6 Mixtures Homogeneous mixtures - A mixture of two or more components that is uniform throughout.Every portion of the sample is identicalComponents cannot be separated out or will not settle out- Can exist as a solid, liquid or gasFor examplebrass (a mixture of zinc & copper.)Salt water (Sodium chloride dissolved in water)air (a uniform mixture of N2, O2, CO2 and trace gases)
7 Mixtures Heterogeneous mixtures – have 2 or more components - components have distinct regions with definite boundaries- can be separated by some physical property- can exist as liquids or solidsFor example:Soil – bits of sand, black soil, organic matterBlood - appears homogeneous but it is actually a heterogeneous mixture of red and white blood cells that are visible under a microscope.
9 In-between Classification Colloid or colloidal dispersion - mixture that is not quite heterogeneous and not quite homogeneousExample – milk is a colloid. The particles are too small to be seen unaided but are small enough that they will not settle outOthers = fog, smoke, whipped cream, mayonnaise, marshmallows
10 Another type of Mixture Suspension – where particles are large enough that they will eventually settle outmixture in which the particles of one substance are scattered in another without dissolvingExample – making a clay pot. The clay particles in the mixture eventually settle out.
11 Differentiating between mixtures Suspension - the particles which are temporarily suspended in the liquid are large enough to collectively make the material appear cloudy. - They will settle out after a while. You can now see that after several minutes, the particles in the suspension have settled to the bottom.
12 Differentiating between mixtures Colloidal dispersion - very small particles spread throughout the liquid which are large enough to reflect light, but not large enough to be seen individually.may look either clear or cloudy in ordinary room light.particles in remain dispersed in the liquid and will not settle out.
13 Differentiating between mixtures A solution, on the other hand, will appear clear even when a light is shown through it.
14 Classifying Matter as Elements or Compounds Pure substances: is matter that has distinct properties and a composition that doesn’t vary from sample to sample. It only has one component. It’s either an:Element: a substance that cannot be broken down any further into simpler substances with different properties.Compound: a substance that is composed of two or more elements that are chemically combined in a fixed proportion by mass.
15 Classifying Matter Elements: Simplest from of matter Presently 114 known elements90 of them are naturally occurring, rest are man-madeEvery element has its own unique set of physical and chemical propertiesEach element has its own name and symbolName is always in EnglishSymbol will be one capitol letter or a capitol letter followed by a single un-capitalized letter.
16 Elements on the Periodic Table What is the periodic table?-a chart that shows all of the known elements-give information about each element
17 Why Know About the Periodic Table?? The periodic table is the most important chemistry reference there is. It arranges all the known elements in an informative array.Its main use is to predict the chemical properties of an element based on where it is located on the table.People familiar with how the table is put together can quickly determine a significant amount of information about an element.
19 Think Inside the Box 6 C Carbon When you look at the periodic table, you should notice that each box represents a different element, and each box contains vital information about the element,Namesymbolatomic numberatomic mass6CCarbon12.011
20 6 C Carbon 12.011 The top number is the atomic number. Every element has its own unique atomic number.The atomic number tells how many protons are in one atom of that element.Since no two elements have the same atomic number, no two elements have the same number of protons.6CCarbon12.011
21 6 C Carbon 12.011 The large letter is the element's symbol Just below that is the element's name.Each element has its own unique symbol and name.6CCarbon12.011
22 6 C Carbon 12.011 Below the name is the element's atomic mass. The atomic mass is the sum of the protons and neutrons in the nucleusThe atomic mass essentially gives you an estimate of how massive one atom of that element is6CCarbon12.011
23 The vertical columns of the periodic table (there are 18) are called groups or families. The elements in a group have the same number of electrons in their outer shell.As you keep counting the columns and you'll know how many electrons are in the outer shell.
24 All of the elements in a period have the same number of atomic SHELLS Both elements in the top row (the first period) have one shell for their electrons. All of the elements in the second period have two electron shells. The number of shells increases as you go down the table.Atoms on the left of the period are usually larger and more lightweight than the smaller, heavier atoms on the right of the period.
25 Electron ShellsElectrons of atoms with similar energy are grouped in an energy level called a shell.The shells closest to the nucleus contain electrons with the lowest energies, whereas shells farther away from the nucleus contain electrons with higher energies
26 3 Main Categories of Elements MetalsNon-MetalsMetalloids
28 Metals On the left side of the table All are solid except for mercury Described as shiny, ductile (most metals can be drawn out into thin wires), malleable (most metals can be hammered into thin sheets )All are good conductors of electricityAll are good conductors of heat
29 Non-metals On the right side of the periodic table Some are solid, some are gases.Bromine is a liquidUnder most conditions are not good conductors of heat or electricity
30 Metalloids (semi-metals) Elements along the stair-step lineThese elements display the properties of metals and non-metals, depending upon the conditions.
32 Forming CompoundsCompounds are pure substances made up of 2 or more different elements in a different proportion.Electrons are primarily involved in the combination of atoms to form compounds.
33 Composition of Compounds Each is put together so that every unit of that compound is identical to every other unitThey are different from every other compound
34 Examples of Compounds Water - made up of hydrogen and oxygen Carbon dioxide – made up of carbon and oxygenRust – made up of iron and oxygenSugar – Made up of carbon, hydrogen and oxygen
35 Naming CompoundsChemical formula – describes exactly what elements and the number of atoms of each element occurs in the smallest particle of that compound.We identify what elements are present by their symbolHow many of those elements present are indicated by the subscript following the symbol.
36 Chemical Formulas Water = H20 means that each unit of water contains 2 atoms of hydrogen and one atom of oxygenSugar (sucrose)= C12H22011How many atoms of each element are in sugar?
37 Review… Atoms Molecules Matter Pure substance Mixture Element Compound Make upMatterWhich can exist asPure substanceMixtureElementCompoundHomogeneousHeterogeneousSodiumChlorineHydrogenSaltWaterSugarAtmosphereSalt in waterBlack CoffeeOil & waterSalt & PepperSugar & sand