Presentation on theme: "Chapter 1: Part 1 Matter & Measurements"— Presentation transcript:
1 Chapter 1: Part 1 Matter & Measurements Introduction: Matter, Measurement and MoleculesIntroduce peopleMeEricaDavidPhilDavid Leanneed to find out what Phil is doing (credentials)Need to establish that we are A TEAM and that the Tutors are fantastic- so they don’t have problems when assessment arrives as a shock
2 Hubble Image Pillars of Creation in M16 Eagle Nebula A Star-forming region Gas Pillars in the Eagle Nebula (M16): Pillars of Creation in a Star-Forming RegionEvery element heavier than Hydrogen was formed by fusion in stars, generally novas at the end of their life just before they explode, starting a new cycle of nebula and star formation. Like it said in Joni Mitchell’s song about Woodstock, “We are Stardust!”. So is everything else made of matter.
3 ChemistryThe study of matter and thechanges it undergoes.Figure 1.2
4 The Scientific Method A systematic approach to solving problems Figure 1.9
5 MatterAnything that has mass and takes up space.
6 Matter Atoms are the building blocks of matter. Each element is made of the same kind of atom.A compound is made of two or more different kinds of elements.Figure 1.1
7 Pure Substances, Elements and Compounds Matter that has distinct properties and a compositionthat doesn’t vary from sample to sample, e.g. salt.ElementA substance that cannot be decomposed into simplersubstances, e.g. oxygen gas.CompoundA substance that is composed of two or more differentelements, so it contains two or more different kinds of atoms, e.g. water.The elemental composition of a pure compound is always the same and this is known as the Law of Constant Composition (or Law of Definite Proportions)Joseph Proust ( )
9 Solid Carbon Polymorphs (different crystal structures, 1 element) Nanotube of soot carbon with open hollow fullerene structure. The network for hegagonal rings permits ready transfer of electrons. These are ultra light weight but conductive and have useful properties for new high tech materials as well as good old fashioned soot and particulate pollution.Rare well crystalline hexagonal graphite crystal from Kimmirut, Baffin Island, Nunavut. This is the most common and abundant form of carbon in nature. It makes a dry lubricant, a conductor of electricity and an industrial mineral for pigments, additives and pencil “leads” when mixed with clays.The diamond, upper right is a 3 carat “diamond shaped” specimen from the Ekati mine at Lac de Gras in the NWT. Diamond is cubic high density carbon derived from deep seated igneous rocks that have come up quickly from greater than 160 km depth in the Mantle. It is mostly used as an industrial abrasive, but a few stones are large, clear and flawless enough to be valuable as precious gems.
10 Monatomic & Molecular Elements Compounds and Mixtures HeAll 3H2BF3
11 MixturesA mixture is a combination of two or more substances in which each substance retains its own chemical identity and can be separated from each other.There are two types:- heterogeneous: a mixture which does not have the same composition, properties and appearance throughout: muesli, sand, rocks.- homogeneous: a mixture which is uniform throughout: solutions, air, smoke, alloys
12 Banded Malachite Cu2(CO3 )(OH)2 & Crystals Copper Sulphate Hydrate & Solution Cu(SO4) – 6H2O Is mostly pure microcrystalline needles of green malachite, where the colour variation is due to crystal form not impurities or mixtures. The well crystallized specimen to the right shows the monoclinic crystal form of this cuprous carbonate hydroxide. This occurs naturally where acid rain alters copper sulfide ore deposits. It also makes the verdigris colour on old copper roofs and weathered bronze artifacts.Cuprous sulfate hexahydrate forms as a blue crystalline solid which dissolves readily to form blue acidic solutions. In the days of alchemy this was called blue vitriol. It is still used as an herbicide and farm poison to “kill ponds”. The solution here is the only true mixture, the others are pure compounds.
15 Properties of Matter Physical Properties Chemical Properties Can be observed without changing a substance into another substance.Boiling point, density, mass, volume, etc.Chemical PropertiesCan only be observed when a substance is changed into another substance.Flammability, corrosiveness, reactivity with acid, etc.
16 Properties of Matter Intensive Properties Extensive Properties Independent of the amount of the substance that is present.Density, boiling point, colour, etc.Extensive PropertiesDependent upon the amount of the substance present.Mass, volume, energy, etc.
17 GaAs a semi-conductor has nearly overlapping molecular bonds Being a semi-conductoris an intrinsic propertyof this compound, dueto its bonds & crystalstructure.
18 Changes of Matter Physical Changes Chemical Changes Changes in matter that do not change the composition of a substance.Changes of state, temperature, volume, etc.Chemical ChangesChanges that result in new substances.Combustion, oxidation, decomposition, etc.
19 Chemical Reactions (Chemical Change) Figure 1.6In the course of a chemical reaction, the reacting substances are converted to new substances.
20 CompoundsCompounds can be broken down into more elemental particles; for example, during the electrolysis of water, the smaller particles hydrogen gas and oxygen gas are created.
21 2H2(g) + O2 (g) H2O (g) + EFuel Cells rely on putting energy in to separate Hydrogen and Oxygen in a closed container by the electrolysis of water. This is the “Charging” cycle. When the fuel cells run down, they follow the closed combustion reaction as written above, recombining the Hydrogen with the Oxygen to obtain water again plus the heat/energy that is converted to work in the engine.
26 SI Units Système International d’Unités Uses a different base unit for each quantity
27 Metric SystemPrefixes convert the base units into units that are appropriate for the item being measured.Table 1.3
28 SI Units - Length and Mass The SI base unit of length is the metre (m).Mass (m) is a measure of the amount of material in an object. The SI base unit of mass is the kilogram (kg).
29 SI Units - Temperature The Kelvin is the SI unit of temperature. It is based on the properties of gases.There are no negative Kelvin temperatures.K = CFigure 1.10
30 Derived SI Units Volume The most commonly used metric units for volume are the litre (L) and the millilitre (mL).A litre is a cube 1 dm long on each side.A millilitre is a cube 1 cm long on each side.
31 Derived SI Units Density Density is a physical property of a substance and is determined through the following formula:density =massvolume =mVor symbolically
34 Uncertainty in Measurements Different measuring devices have different uses and different degrees of accuracy.Figure 1.12
35 Significant FiguresAll digits of a measured quantity, including the uncertain, are called significant figures.The greater the number of significant figures, the greater the certainty of the measurement.
36 Significant Figures All nonzero digits are significant, e.g. 123.45 Zeros between two significant figures are themselves significant, e.gZeros at the beginning of a number are never significant, e.g =Zeros at the end of a number are significant if a decimal point is written in the number, e.g has six significant figures but has only five significant figures
37 Significant FiguresWhen addition or subtraction is performed, answers are rounded to the least significant decimal place.When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation.
38 Precision and Accuracy Accuracy refers to the proximity of a measurement to the true value of a quantity.Precision refers to the proximity of several measurements to each other.Figure 1.15
39 Reading Errors & Interpolation 27°+/- 1°CHere the large division marks are for 10°C while the smaller ones are for 5°C. The red dyed alcohol in this thermometer is about 40% of the way between 25°C and 30°C so: (30°-25°) x 0.4 = 2° but this is above 25° so we add 25° + 2° = 27°. Our reading error is about +/- 1° so we write down 27° +/- 1° C, presuming we can reproducibly read to 20% of the smallest division. Pretty finicky hair splitting, but we try to be as precise as we can.