01/09/2014 elements compounds and mixtures. 01/09/2014 element, mixture or compound? salty...
TRANSCRIPT
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Elements Compounds Elements Compounds and Mixturesand Mixtures
11/04/23Element, mixture or Element, mixture or compound?compound?
Salty water Hydrogen
Hydrochloric acid
Sodium chloride (salt)
Diamond
Air
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Is it an element, compound or Is it an element, compound or mixture?mixture?
• Scientists like to classify things.• One way that scientists classify
matter is by its composition.• Ultimately, all matter can be
classified as mixtures, elements and compounds.
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Why isn’t it a good idea Why isn’t it a good idea to classify matter by its to classify matter by its
state?state?
• Because one kind of substance can exist in more than one state – such as H20. And matter changes phases rather easily.
• Remember Topic 3 – The World of Chemistry
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What is an element?What is an element?
• An element is a pure substance that cannot be broken down into simpler substances.
• A pure substance is a substance in which there is only one type of particle.
• An element is a chemical that contains only one type of atom.
• Pure gold is an element because it contains gold atoms only.
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All the elementsAll the elements are found on are found on thethe
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What are atoms?What are atoms?
• All chemicals are examples of matter.
• All matter is made up of extremely small particles called atoms.
• Learn more about atoms in LO 4
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What are compounds?What are compounds?A compound is a substance that contains different elements (different atom types) chemically joined together
Here are some examples:
Glucose
Methane
Sodium chloride (salt)
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CompoundsCompounds
• A compound is a pure substance composed of two or more elements that are chemically joined together.
• Compounds are new substances produced by chemical reactions. To be chemically combined, the elements in the compound need to have reacted with one another.
• Most elements are not found alone in nature, but rather combined with other elements. Most substances you encounter are compounds!
• A compound has fixed proportions of the different elements. Eg. water
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Glucose is a compoundGlucose is a compound
Containing the elements:•Carbon
•Hydrogen•oxygen
CC66HH1212OO66
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What are molecules?What are molecules?
• Molecules are groups of atoms joined together.
• The compound water is a molecule containing 2 hydrogen atoms joined to an oxygen atom.
• The element oxygen forms molecules of oxygen gas = O2
Oxygen molecules
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MixturesMixtures
• A mixture is a combination of two or more substances that are not chemically combined.
• When you mix up chemicals and no new substance is produced then a mixture is formed.
• Substances in a mixture retain their identity, they do not change into something else.
• Mixtures can be physically separated through physical change. Eg: picking the pecans out of pecan pie, boiling salt water to evaporate the water and leave the salt.
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AirAirAir is a mixture…which can be separated – see LO 8
79% 79%
21% 18%0.03%
1%
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Classification of Matter Classification of Matter Overview Overview
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Test yourselfTest yourself
Is it an element, compound or mixture?
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(Gas)
One Element The Same Element(Solid)
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This one likes to go round in pairs as a
gas (molecules)
Another element A mixture of two elements
11/04/23This is not a mixture, it is a
COMPOUND of two different elements
This is just a mixture of two
elements
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Element, Compound or
Mixture ?
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Element, Compound or
Mixture ?
Element
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Element, Compound or
Mixture ?
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Element, Compound or
Mixture ?
Element
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Element, Compound or
Mixture ?
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Element, Compound or
Mixture ?
Mixture
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Element, Compound or
Mixture ?
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Element, Compound or
Mixture ?
Compound
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Element, Compound or
Mixture ?
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Element, Compound or
Mixture ?
Compound
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Element, Compound or
Mixture ?
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Element, Compound or
Mixture ?
A mixture of a compound and
an element
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What do we call these things?
6 Atoms which happen to be of 3 different elements
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What do we call these things?
A Molecule
Yes, it also happens to be 2 atoms joined
together but we don’t call it “2 atoms joined together” we say it is
one molecule
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What do we call these things?
A Molecule of a compound
2 molecules of a compound