Elements, Compounds and Mixtures

Holt: Chapter 4Fusion: Unit 3, Lesson 5

Mixtures• A mixture is a combination of two

or more substances that are not chemically combined.• No chemical changes• Sometimes you can see the

components, sometimes you cannot• Not mixed in a definite ratio• Separate through physical methods

• Distillation- uses boiling points• Magnets- use magnetism• Centrifuge- uses density• Filtering- separates according to size

• Examples:

Types of Mixtures

•Solutions•Suspensions•Colloids

Solutions• A mixture that appears to be a

single substance• Process by which they spread is

dissolving• Solute- the substance being

dissolved• Solvent- the substance doing the

dissolving (water is the universal solvent)• Particles never settle, cannot be

filtered; do not scatter light

Examples of Different States in Solutions

Gas in gas Dry air (oxygen in nitrogen)

Gas in liquid Soda (carbon dioxide in water)

Liquid in liquid Antifreeze (alcohol in water)

Solid in liquid Salt water (salt in water)

Solid in solid Brass (zinc in copper)

Concentration of Solutions

• Concentration- the measure of the amount of solute dissolved in a solvent• Can be expressed in grams of solute per milliliter of solvent (g/mL)• Remember…solubility is the ability of a substance to dissolve• Mixing, heating and crushing can help dissolve more quickly

Suspensions

• Suspension- is a mixture in which particles of a material are dispersed throughout, but are large enough to settle out.• Suspensions CAN be separated

by filtration• Scatter light

Colloids

• A colloid is a mixture in which the particles are dispersed throughout and not heavy enough to settle out• Particles are small and fairly well

mixed; scatter light• Cannot be separated by filtration

• Examples:

Elements

• Element- a pure substance that cannot be separated into simpler substances by chemical or physical means• Pure substance- is a substance in

which there is only one type of particle• Particles are atoms• Each element has unique

properties- not dependent on how much of an element you have

• Remember…characteristic properties? Physical and chemical properties?• Elements do share some

properties• Grouped on the periodic table by

properties

Categories of Elements

Metals Nonmetals Metalloids• shiny• Good conductors of

heat and electricity• Malleable• Ductile

• dull• Poor conductors of heat

and electricity• Solids tend to be brittle

and not malleable

• Have properties of both metals and nonmetals

• Semi-conductors

Compounds

• Compound- a pure substance composed of two or more elements that are chemically combined• Combine by reacting, undergoing chemical change• Particles are called molecules, which are formed when atoms of two

or more elements combine• Compounds are DIFFERENT from the elements that make it• Elements join in specific mass ratios• Ex: H2O = 1:8

Familiar Compounds

Compound Elements combinedTable salt Sodium and chlorineWater Hydrogen and oxygenVinegar Hydrogen, carbon, oxygenCarbon dioxide Carbon, oxygenBaking soda Sodium, hydrogen, carbon,

oxygen

Properties of Compounds

• Each compound has its own physical properties• Can be identified by chemical properties• A compound’s properties differ from the elements that formed it

Breaking down Compounds

• Broken down through chemical changes• Sometimes have to be broken into simpler compounds, then elements• Two ways to break down: apply heat or electric current