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ChemistryChemistry
The study of The study of ChemicalChemical & & PhysicalPhysical PropertiesProperties and and ChangesChanges of Matter of Matter
ChemistryChemistry
What is Chemistry?What is Chemistry?– The study of the of The study of the of mattermatter
What is What is matter?matter?
How can/will How can/will mattermatter changechange when you do when you do something to it something to it
What is Matter?What is Matter?– Anything that has mass and takes up space (volume)Anything that has mass and takes up space (volume)
All “stuff” around you is matterAll “stuff” around you is matter
All matter is made up of substances or mixturesAll matter is made up of substances or mixtures
Substances v. MixtureSubstances v. Mixture
Substance – All the same stuff (“pure”).Substance – All the same stuff (“pure”).No matter how much you have, it is all still the No matter how much you have, it is all still the
same stuff.same stuff.Ex: a “pure” sample of water is only HEx: a “pure” sample of water is only H2200
Substances v. MixtureSubstances v. Mixture
SubstancesSubstances consists of: consists of:1.1. ElementsElements (single atoms) (single atoms)
i.e. Carbon (C), Oxygen (O) i.e. Carbon (C), Oxygen (O)
2. Molecules2. Molecules (combinations of elements) (combinations of elements) i.e. Water (Hi.e. Water (H22O), Carbon Dioxide (COO), Carbon Dioxide (CO22), Salt (NaCl)), Salt (NaCl)
Sodium Chloride (table salt)Water Carbon Dioxide
Molecules are simply a bunch of atoms “stuck” together!
electron
neutron
proton
Substances v. MixtureSubstances v. Mixture
MixtureMixture– Made of two or more substances – (elements, Made of two or more substances – (elements,
molecules or both) that are together in the molecules or both) that are together in the same place, but same place, but NOT chemically bondedNOT chemically bonded. .
Salt Water Sand/dirt
Salad
Substances v. MixtureSubstances v. Mixture
If it’s a mixture, you can separate out the If it’s a mixture, you can separate out the parts relatively easily. parts relatively easily. – (i.e. filtering/distilling)(i.e. filtering/distilling)
Demo: filter Italian salad dressing
DrainFill
Filter: Pure Substance Leftover
Pure Substance
Mixture
What are Properties?
How do you identify a specific substance?How do you identify a specific substance?-What atoms/molecules make it up!-What atoms/molecules make it up!
Problem: Problem: WE CAN’T SEE THEMWE CAN’T SEE THEM! They are way too small!! They are way too small!
But we can use “But we can use “PropertiesProperties” to identify them” to identify them
Properties are “Properties are “identifying characteristicsidentifying characteristics” (clues) of ” (clues) of elements/substances. All substances have their own elements/substances. All substances have their own properties unlike any other substanceproperties unlike any other substance
Can Identify elements, molecules and substances Can Identify elements, molecules and substances (combination of elements/molecules) if you know enough of the (combination of elements/molecules) if you know enough of the properties (clues)properties (clues)
So what if we have a substance that we need to identify?
Demo: which student am I describing?
Intro: Substance IDIntro: Substance IDTry to Identify the 3 substancesTry to Identify the 3 substances– How do you know or can tell what it is?How do you know or can tell what it is?
Demo: Three Cups: Salt, Sugar & Mystery Substance
Before you are a sample of Sugar, Salt, and a mystery substance
First just look at them and try to tell them apart
Now smell them and try to tell them apart
Now taste them and try to tell them apart
The main point: If we know enough “properties” we can identify a substance from other substances.
2 Types of Properties:2 Types of Properties:
PhysicalPhysical-Describes generally
how a substance appears, feels, etc... Can usually be easily observed without testing anything.
Examples: Taste, Smell, Texture, Color, size, Solid/Liquid/Gas, mass, etc…
ChemicalChemical-Describes how one
substance changes into a new substance. Or how it will act under certain conditions. What can/will it do?
Examples: Oxidation, +/- Charge, release of
bubbles, causes a new smell/color, ALL REACTIONS!
Physical ChangePhysical Change The substance simply
changes shape, size, solid/liquid/gas, etc…
The substance/element DOES NOT CHANGE!!!
It only changes how it appears!!!
EX: Freezing water
Chemical ChangeChemical Change The substance
burns/reacts and can release some of it’s “parts” into the air.
The substance completely changes to something brand new!
EX: Iron Iron Oxide
Demo: Burning Paper
Demo: Breathing Fire
Q: What if we try to do something Q: What if we try to do something to the substance? Change it to the substance? Change it
somehow…somehow…
Identifying MatterIdentifying MatterOur Brains instinctively use physical properties to identify Our Brains instinctively use physical properties to identify matter all the time – but can also be deceiving. matter all the time – but can also be deceiving.
Chemists also use chemical properties to help identify Chemists also use chemical properties to help identify unknown substances. unknown substances.
Ding! Ding! Ding! It’s …
PhysicalCharacteristics
Chemical Characteristics
a characteristic of a pure substance that can be
observed without changing it into another
substance.
a characteristic of a pure substance that describers its ability to change into different substances.
Properties are used to solve Properties are used to solve crimes!crimes!
Ding! Ding! Ding! The answer to the mystery is…
PhysicalCharacteristics
Chemical Characteristics
What do you observe at the crime scene?
Perform some tests to see what chemicals are at the
crime scene.
List Physical Characteristics: List Chemical Characteristics:
Physical ReviewPhysical Review Chemical ReviewChemical Review
Describes how the substance or mixture appears, feels, dimensions, etc...
Describes the substances ability to react with other substances.
An change of the substance w/o changing the substance. Elements and molecules remain the same!
–Bend, twist, crush, tear, melt, boil, etc…
An change of the substance by reacting it with another substance to make it a new substance.
–Burn (combust), rust, tarnish, light, new smell, fizzing, etc…
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