Elements, Compounds, and Mixtures

And what’s the difference….

Matter

• Anything that has mass and takes up space

• Examples of matter

• Examples of non-matter

Atoms and Elements

• Atom = the smallest unit of an element that has all the properties of the element.

• Element = a substance that cannot be broken down into other substances by a chemical process.

• Elements are written as symbols» Ex) Fe, Al, O, H» See Figure 3 in text

Molecule

• Atoms can join to make millions of different molecules

• They are the smallest unit of a substance (that still behaves like that substance)

• They can be made of one element, or many elements

Compounds

• Compound= A substance composed of a given combination of elements. It can be broken down into those elements by a chemical means

»Ex) H2O, can be separated by chemical methods

Compounds and Elements(Give examples of each)

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al Elements

• Compounds always contains different elements.

• Properties of compounds are usually very different than the elements they’re made of.

Compounds and Elements(Give examples of each)

• Compounds always have the same composition even though they have different atoms.

• Chemical formulas represent compounds.– Use indigo as an example

Mixtures & Pure Substances

Mixtures and Pure Substances

• Virtually all matter around us consists of a mixture of substances.

• Mixture: something that has a variable composition.

» Ex) wood, coffee, water

• Pure Substance: Always have the same composition throughout (whether compound or element)

Mixtures and Pure Substances Cont.

• Mixtures can always be separated into pure substances (element or compound)

• Mixture Two or more substances

Ex) Air Oxygen CO2Nitrogen ArgonWater Other

2 Types of Mixtures

• 1) Homogenous Mixture: is the same throughout a solution.

» Ex) Salt water mixture, Air, Brass (made of copper and zinc)

• 2) Heterogeneous Mixture: a mixture who’s regions have different properties from those in other regions.

» Ex) salads

Gas and Liquid Mixtures

• Soda is a mixture of water, flavoring and dissolved carbon dioxide (CO2)– CO2 bubbles form in the liquid when the can is

opened.• Gasses in cold tap water will bubble out when

the water warms up• Liquid and gas mixtures that are stable are

called foam.

What's that mixture?

• Based on the size of the largest particle, a mixture can be classified as a solution, a suspension, or a colloid.

• The size of particles in a mixture have an effect on the properties of the mixture.

Solutions

• Homogeneous mixture• The particles are too small to settle out of

solution, be trapped by a filter, or scatter light.

• Ex) Sugar water

Suspensions• Heterogeneous mixture• Particles settle out of a mixture or are

trapped by a filter because they are larger then the particles in the solution.

• B/c larger particles can scatter light in all directions , suspensions are cloudy.

• Ex) Yoohoo, chocolate milk.

Colloids

• Contains particles that are in between in size between small particles in a solution and the large particles in a suspension.

• Like Solutions, colloids DON’T separate into layers.

• Cannot use a filter to separate the parts of a colloid.

• Ex) Fog