Elements, Compounds and Mixtures Elements, Compounds and Mixtures.
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Elements, Compounds and Mixtures
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Transcript of Elements, Compounds and Mixtures Elements, Compounds and Mixtures.
Elements, Compounds and Mixtures
Elements, Compounds, Mixtures
Ultimately, all matter can be classified as mixtures, elements and compounds
Questions to ask to help classify! Is the matter uniform throughout? Can it be separated by physical
means? Can it be separated by chemical
means?
Why isn’t it a good idea to classify matter by its
phases?
Because one kind of substance can exist in more than one phase – such as H20. And matter changes phases rather easily.
Elements Elements are pure substance that
cannot be separated into simpler substance by physical or chemical means.
Compounds
Pure substance composed of two or more different elements joined by chemical bonds.
Made of elements in a specific ratio that is always the same Has a chemical formula Can only be separated by chemical means, not physically
H2O
CO2
NaCl
Compounds
Water is a compound.
Water can be broken down into simpler substances – hydrogen and oxygen through electrolysis.
Mixtures A combination of two or more pure
substances that are not chemically combined.
substances held together by physical forces, not chemical
No chemical change takes place Each item retains its properties
in the mixture They can be separated physically
Chem4kids.com
Heterogeneous Mixtures
Does not appear to be the same throughout.
Particles are large enough to be seen and to be separated from the mixture sometimes by filtering.
Examples of heterogeneous mixtures
Sand and pebbles Chicken noodle soup Granite Oil and water
Homogeneous Mixtures
A mixture that appears to be the same throughout.
The particles that make up the mixture are very small and not easily seen
Cannot be separated by filtering Some examples: salt water solution,
kool aid, ice tea mix and water
Suspensions
Are mixtures in which the particles are larger than ones found in solution. They are insoluble
( they don’t dissolve) and will settle out if left alone. They are heterogeneous.
Examples: blood, oil and water, muddy water, snow globe, glitter and water
They also do not transmit light they scatter light or block light.
Can be separated by filtering
Colloids
In a colloid the particles are mixed together but not dissolved.
The particles are relatively large and are kept permanently suspended.
Cannot be easily filtered
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Examples of Colloids
milk, mayo, cheese, whipped cream, deodorant, fog, gelatin,
smoke, toothpaste
detergents They are
homogeneous mixtures
•
Solutions
A solution is a type of homogeneous mixture formed when one substance dissolves in another.
A solution always has a substance that is dissolved( the solute) and a substance that does the dissolving. ( the solvent)
The universal solvent: Water
Types of Solutions
Dilute-less solute than solvent.
Concentrated Saturated- A solution which has as
much solid dissolved in it, as it possibly can contain.
Concentration- the amount of a particular substance in a given quantity of a mixture
Solubility-the ability of one substance to dissolve in another at a given temperature and pressure
Types of solutions
Gas Gas Air (oxygen in nitrogen)Gas Liquid Soda water (carbon dioxide
in water)Solid Liquid Ocean water (salt in water)
Solute Solvent Example
Solid Solid Brass ( copper and zinc)
.
Air is a solution of oxygen and other gases dissolved in
nitrogen
Alloys are Mixtures
Alloys are solid solutions of metals or nonmetals dissolved in metals.
Alloysexamples
)
Brass is an alloy of copperand zinc.
Stainless steel is a mixtureof iron and chromium.
