Elements, Compounds, & Mixtures

3.1 ELEMENTS Element- A pure substance that cannot be

separated into simpler substances by chemical or physical means.

Pure Substance- A substance in which there is only one type of particles

PROPERTIES OF ELEMENTS

Each element has its own characteristic properties. These include boiling/melting point, density,

reactivity, flammability, etc.

An element may share one or two properties with another element, but it will not share all its properties with another element. There will be specific properties for each element.

Classifying Elements You can use properties to identify

elements. Think about how many types of dogs

there are. How do you tell one breed from another?

Categories of Elements Metals NonmetalsMetalloids

Classifying Elements Metal- an element that is shiny and

conducts heat and electricity well

PropertiesMalleable – ability to be hammered into sheetsDuctile – ability to be drawn into wires

CLASSIFYING ELEMENTS Nonmetal – an element that conducts

heat and electric poorlyProperties

1. dull 2. brittle – not malleable

Metalloid- an element that has properties of metals and nonmetalsProperties

1.some are shiny

2. some are dull

3. somewhat malleable and ductile

4. some are good conductors of heat and electricity

5. some are poor conductors of heat and electricity

CLASSIFYING ELEMENTS

CLASSIFYING ELEMENTS  Appearance Conductivity Physically Example

 Metal  

  Shiny

 Good

 malleable., ductile

 Lead, Copper

 Nonmetal  

  Dull

 Poor

 Brittle

 Sulfur, oxygen

  Metalloid 

 Some Shiny/ some dull

 Some good/ some poor

 Somewhat malleable and ductile

 Silicon, boron

3.2 COMPOUNDS Compound- a substance made up of atoms

of two or more different elements joined by chemical bonds Examples: H2O (water), NaCl (table salt)

A particle of a compound is called a molecule Elements do not randomly combine. They join into a

specific ratios according to their masses.

PROPERTIES OF COMPOUNDS Each compound has its own physical

properties and chemical properties. The properties of a compound are

different from the properties of the elements that form it. Sodium + Chlorine Table

Salt Explosive soft metal Yellow Piousness Gas

BREAKING DOWN COMPOUNDS Some compounds can be broken down

into their elements or simpler compounds by chemical means.

Sometimes energy in the form of heat is needed to do this.

3.3 MIXTURES Mixture- A combination of two or more

substances that are not chemically combined.An example would be a salad (or salsa as in

the picture). The cheese, sauce, and dough are still the same items after you make the pizza.

PROPERTIES OF MIXTURES Sometimes you cannot see all the

components like in salt water This is called a homogeneous mixture. It includes salt and water.Since mixtures are not chemically

combined, you can separate the different substances by physical methods.

Components in a mixture do not need to be in a specific ratio.

SEPARATING MIXTURES Sometimes you can just pick ingredients

out of a mixture (pizza) Other ways to separate mixtures include:

evaporation – separates a mixture based on boiling points Ex: salt in water

magnet – anything ferromagnetic will stick to the magnet EX. Iron & Aluminum nails in box

distillation – separates a mixture based on density. Ex: crude oil – gasoline & propane

centrifuge – separates based on particle size Ex: blood

COMPOUNDS VS. MIXTURES

Mixtures Compounds Made of elements,

compounds or both

Made of elements

No change in original

properties of components

Change in original

properties of components

Separated by physical

means

Separated by chemical

means

Formed by using any ratio

of components

Formed using a set ratio

of components

MIXTURE VS. COMPOUND VS. ELEMENT

SOLUTIONS, SUSPENSIONS, & COLLOIDS

SOLUTIONS Solution- A mixture that appears to be a

single substance. Particles are small & cannot be filteredSolutions have the same composition

throughout.Example: Salt Water

Solute- Substance that is dissolved. (Salt) Solvent- The substance in which the solute is

dissolved. (water)

SOLUTIONS CONTINUED The term soluble means able to

dissolve. Insoluble means unable to dissolve.Solutions can be solids, liquids, or gases.

Solubility- Measure of the amount of solute dissolved in a solvent. This is expressed as g/mLTo increase solubility:

heat stir crush – smaller particles

 

COLLOIDS Colloid A type of mixture in which the

particles are dispersed throughout but are not heavy enough to settle outParticle size is larger than that of a solution

but small enough they will still pass through a filter.

Examples of colloids: milk, fog

COLLOIDS Colloids scatter light. (fog) You can actually

see the beam of light in the colloid.

SUSPENSIONS Suspensions- A mixture in which the

particles of a material are dispersed throughout a liquid or gas but are large enough that they settle out.Particles are large enough to settle out.Suspensions can be separated by passing

through a filter.Examples: Italian salad dressing, muddy

water

ELEMENTS, COMPOUNDS, MIXTURES

  Elements Compounds Mixtures

How many parts make it up?

 1  2 or more  2 or more elements or compounds

Pure: more than one substance?

 pure  pure  Not pure

Chemically or physically combined?

 N/A  Chemically physically

Chemical change to make them?

 N/A  Yes no

Fixed ratio?  N/A Yes no

How separated: chemically/physically?

 N/A Chemically physically

SOLUTION, SUSPENSION, COLLIOD

  Elements Compounds Mixtures

How many parts make it up?

 1  2 or more  2 or more elements or compounds

Pure: more than one substance?

 pure  pure  Not pure

Chemically or physically combined?

 N/A  Chemically physically

Chemical change to make them?

 N/A  Yes no

Fixed ratio?  N/A Yes no

How separated: chemically/physically?

 N/A Chemically physically