Unit 1- The Science of Chemistry• Allotrope• Atom• Chemical • Chemical change• Chemical properties• Chemical reaction• Compound• Conversion factor• Density• Element• Extrinsic properties• Heterogeneous• Homogeneous
• Intrinsic properties• Mass • Matter• Mixture• Molecule• Physical change• Physical properties• Pure substance• Reactant • States of matter• Volume
Why study chemistry?• It plays a vital role in your
everyday life• EVERYTHING is made up of
chemical elements• Clothes, food, make up, sports
equipment, computers, --- all chemistry!– Even the things you can’t see
chemistry• Air, gases, atoms, cells
An example of everyday chemistry…
…..and why you don’t want to swallow it
What is chemistry?• Chemistry is concerned with the properties of
chemicals and the changes they can undergo.• A chemical is:
– a substance that has a definite composition– Ex: H2O, CO2
• Some are natural, some are man-made and some are natural but manipulated by man– Carbon monoxide?– Polyethylene?– Aluminum?
Chemical Reactions are happening ALL the time!!
– Chemical Reaction- the process by which one or more substances change to produce one or more different substances
• Cooking/baking, taking photos, digesting food, turning on a light, starting an engine, lighting fireworks
• Chem rx’s are necessary for living things to grow and dead things to decay
Matter Matters!– anything that has mass or volume = matter
• Mass- quantity of matter contained in an object– Measured with a balance or scale
• It’s related to weight but NOT THE SAME• Weight- force produced by gravity acting on mass
(expressed in newton)– In lab “weigh” usually means to find mass
• Volume- the space an object occupies– A block l x w x h– A liquid graduated cylinder– A gas same vol as the container it fills
Using density to identify a substance
• Density- ratio of mass to volume
- density is the same regardless of sample size (**it can identify a substance)
- it can also be found by the slope of a graph
• 1- weigh the substance (to find mass)• 2- use water displacement in graduated cylinder (to find
volume)• 3- divide mass by volume
Units of Measurement
King Henry Died Unexpectedly Drinking Chocolate Milk
Converting one unit to another:
• Use a conversion factor• **unit you want to find goes on top of factor**
How many kg in 2345g? 2345g x 1kg/1000g = 2.345kg (g’s are crossed out)
Convert these practice problems:• 7.359m = ________ cm• 8.0km = ________ Decameters• 2.43mm = ________ m• 51mL = __________ hL• 1.43cm = ________m
*K H D U D C M
• Physical property- can be determined without changing the nature of the substance– Ex- color, texture, melting point, boiling point (physical changes)
**matter can’t be described by physical property only• Chemical property- describes a substance’s ability to
participate in a chemical rx– Ex: reacts with O2, reacts with light, forms a precipitate, combustion,
solubility
Properties of Matter
Extrinsic vs. Intrinsic Properties • Extrinsic- doesn’t depend on the amount of
matter– Color, odor, luster, malleability, ductility,
conductivity, hardness, melting/freezing point, boiling point, density
• **can be used to identify a substance
• Intrinsic- depends on the amount of matter– Mass, weight, volume, length
• **CAN’T be use to identify a substance
States of Matter• Solid- Fixed volume and shape
– due to particle arrangement, tight in rigid structure, only vibrate slightly
• Liquid-Fixed volume, no fixed shape, particles not held together as strongly as solids (particles move past one another…takes shape of container)
• Gas-No fixed volume or shape– particles weakly attracted to one another,
move at high speed, fill container they occupy
Classifying matter• All matter is composed of atoms• Atoms can be mixed physically or chemically to make
up different types of matter• If they are mixed chemically:
– Pure substances- have properties (phys or chem) that identify it
– 2 types: elements and compounds• If they are mixed physically:
– Mixtures-– 2 types: Homogeneous
and heterogeneous
• contain 1 type of atom– Has a unique set of phys. and chem. properties, is
represented by a chemical symbol– Ex:
– Can be a single atom or molecule• Helium gas is individual atoms- monotomic gas (He)• Molecules- 2 or more atoms that can exist as a single unit-
diatomic molecules - H2, N2, F2, O2, I2, Cl2, Br2
• “ have no fear of brutally interesting chemistry” – Allotrope- different molecular forms of the same element
Ex: O2, O3
Pure Substance: Elements
Pure Substance: Compounds• composed of more than 1 type of atoms in a definite
proportion– Represented by formulas Ex: H2O– Subscripts represent #of atoms of each element
– Compounds are classified by their properties, bonds or the elements they are made of
Atoms Compound
Different representations of aspirin:
Mixtures• Contain 2 or more pure substances
– ex: air, blood
• Vary in composition and properties– More or less sweet iced tea, diff karat gold, metal alloys
• Homogeneous- substances distributed uniformly throughout
• Heterogeneous- substances not easily mixedMixture Compound
Physically joined together Chemically joined together
Properties similar to substances Different properties from substances
Various proportions of substances
Definite composition
Separating Mixtures
• Filtration- to separate precipitate from solution• Distillation- separate by boiling point• Evaporation- remove water from a mixture• Chromatography- separate by solubility
Changes of Matter• Physical- a change of state
– Doesn’t change identity– Ex: ice water steam (all H2O)– Ex: dissolving salt in water
• Chemical- substance changes and new one forms– Set up as an equation with reactants (used by rx)
and products (made by rx)
• In chemical reactions atoms in reactants are rearranged– Atoms aren’t created or destroyed so mass
doesn’t change neither does energy or charge• Evidence of chemical change:
– Production of a gas (bubbling,odor)– Precipitate (2 clear solns cloudy)– Release/absorb E (temp change, light emitted)– Color change (phenolphthalein in ammonia)
--Classification of Matter--
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