1) To explain how scientists classify living things 2) To identify the 6 kingdoms of life.
Elements, Compounds and Mixtures...Elements, compounds, mixtures, Scientists like to classify...
Transcript of Elements, Compounds and Mixtures...Elements, compounds, mixtures, Scientists like to classify...
Elements, Compounds
and Mixtures
Elements, compounds, mixtures,■ 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.
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.
Why isn’t matter classified according to its physical
characteristics, such as color?
■ Scientists wouldn’t find it very useful to group gold, sunflowers, and the sun together.
■ Scientists ask themselves these questions?■ Is the matter uniform
throughout?■ Can it be separated by
physical means?■ Can it be separated by
chemical means?
By asking these questions scientists can classify matter into:
■Elements, Compounds, Mixtures
Elements■ Elements are the simplest pure substance.
■ An element can not be changed into a simpler substance by heating or any chemical process.
■ The smallest particle of an element that has the properties of that element is called an atom.■ An atom is the basic building block of
matter.■ There are more than one hundred known
elements in the universe listed on the periodic table of elements.
Elements■ An element is a pure substance (only 1
type of particle) that cannot be separated into simpler substances by physical or chemical means.
Elements■ All elements are
made of atoms.■ Atoms of the
same element are alike.
■ Atoms of different elements are different.
Elements■ In 1813, a system of
representing elements with symbols was introduced.■ Each symbol consists of
one or two letters.■ Two letters are needed
for a chemical symbol when the first letter of that element’s name has already been used.
Common ElementsAluminum AlBromine BrCalcium CaCarbon CGold AuHelium HeHydrogen HNitrogen N
Compounds■ Compounds are also
pure substances.■ But compounds are
made from more than one element.
■ Water is a compound.
■ Water can be broken down into simpler substances – hydrogen and oxygen.
■ H20 is the chemical formula for water, and H2O2 is the formula for hydrogen peroxide.
■ The formula tells you which elements make up a compound as well as how many atoms of each element are present.
Compounds Have Formulas
How to read a formula
H20This is a subscript. It tells us how many atoms of that element exist in one unit of that compound.
Water is made of 2 H atoms and 1 O atom.
No subscript is used when only one atom of an element is present.
Let’s try it…Sulfuric AcidH2SO4
■ 2 Hydrogen■ 1 Sulfur■ 4 Oxygen
Hydrogen Peroxide H2O2■ 2 Hydrogen■ 2 Oxygen
Carbon Dioxide CO2■ 1 Carbon■ 2 Oxygen
Carbon Monoxide CO■ 1 Carbon■ 1 Oxygen
Calcium Carbonate CaCO3■ 1 Calcium■ 1 Carbon■ 3 Oxygen
Mixtures ■ A mixture is a combination of two or more substances where there is no chemical combination or reaction.
A mixture is a combination of two or more substances where there is no chemical combination or reaction.
Mixtures combined physically in no specific proportions. They just mix.
Solids, liquids and gases can be combined
to create a mixture.
Examples of Mixtures
chicken noodle soup
pizza – yes, that would be Yoda…
salad
Properties of Mixtures:•Each substance in a mixture keeps its identity•You can physically separate them
•They also contain elements, compounds, or both•And they can be formed using any ratio of components
Mixtures may be homogeneous or
heterogeneous
Homogeneous
■ The prefix “homo” indicates the same
■ Homogeneous mixtures have the same appearance and properties throughout the mixture
Examples of homogeneous mixtures
Milk, toothpaste, and mayonnaise are homogeneous mixtures. They are also colloids.
Heterogeneous
■ The prefix “hetero” indicates difference
■ Heterogeneous mixtures consist of visibly different substances
Types of Mixtures
■ There are THREE types of mixtures:
■Solutions■Suspensions■Colloids
Solutions■ A solution is a mixture that appears to be
a single substance, but it is actually composed of 2 or more substances that are distributed evenly amongst each other.■ SOLUTIONS ARE HOMOGENEOUS
carbon dioxide is dissolved in water
sugar & Kool-Aid powder are dissolved in water
salt is dissolved in water
A solution has two parts■ The substance
in the smallest amount and the one that DISSOLVES is called the SOLUTE
▪The substance in the larger amount is called the SOLVENT - it does the dissolving
▪IN most common instances water is the solvent
Suspensions■ A suspension is a mixture in which
particles of a material are dispersed throughout a liquid or gas, but are large enough that they settle out.■ SUSPENSIONS ARE HETEROGENEOUS
That water is disgusting!
Italian dressingmuddy water
Colloids■ A colloid is a mixture in which the
particles are dispersed throughout but are not heavy enough to settle out.■ COLLOIDS ARE HOMOGENEOUS
milkmayonnaise
Colloids have properties of both solutions & suspensions.
Compounds vs MixturesCompounds Mixtures
Combine chemically forming molecules
Not chemically combined
Combine in set proportions
Can combine in any proportion
Separated chemically
Separated physically
Element, Compound, or Mixture?Rocks
Element, Compound, or Mixture?Rocks
Element, Compound, or Mixture?Copper
Element, Compound, or Mixture?CopperCu
Element, Compound, or Mixture?Jelly Beans
Element, Compound, or Mixture?Jelly Beans
Element, Compound, or Mixture?Table Sugar
Element, Compound, or Mixture?Table SugarC12H22O11
Element, Compound, or Mixture?Diamond
Element, Compound, or Mixture?DiamondC
Element, Compound, or Mixture?Tea
Element, Compound, or Mixture?Tea
Element, Compound, or Mixture?Salt
Element, Compound, or Mixture?SaltNaCl
Element, Compound, or Mixture?Neon Gas
Element, Compound, or Mixture?Neon GasNe
Element, Compound, or Mixture?Salad
Element, Compound, or Mixture?Salad
Element, Compound, or Mixture?Pure Water
Element, Compound, or Mixture?Pure WaterH2O
Element, Compound, or Mixture?Aluminum
Element, Compound, or Mixture?AluminumAl
Element, Compound, or Mixture?Lemonade
Element, Compound, or Mixture?Lemonade
Element, Compound, or Mixture?Silver
Element, Compound, or Mixture?Silver
Ag
Element, Compound, or Mixture?Sand
Element, Compound, or Mixture?Sand
EXTRA!■ Human body is made up of 28 elements?■ About 99% our mass is made up of the 6
main elements■ Oxygen (65%)■ Carbon (18%)■ Hydrogen (10%)■ Nitrogen (3%)■ Calcium (1.5%)■ Phosphorus (1.5%)
Challenge Time■ Are YOU an element, mixture or
compound?
Identify the following with as many terms as apply
1. Table salt2. Salad3. Mayonnaise4. Italian dressing5. Pepsi6. Oxygen7. Hydrogen8. Water
Mixture
Element
Compound
Suspension
Colloid
Solution
Homogeneous
Heterogeneous
Comparing Elements, Compounds & Mixtures
Elements Compounds
Mixtures
What are they made up of?
Can they be broken down? If
yes, how?
Do they keep or lose their original
properties?
Draw what the particles look
like.