Classification of Matter Stuff of which all materials are made: anything that has mass and takes up space.

Matter All matter is composed of atoms Atoms are extremely small building blocks of matter Atoms cannot be broken down into smaller pieces by chemical means Atoms are the smallest distinct units in a sample of matter

Physical Classification

Let’s look at Pure Substances

Pure Substances - Elements Pure substance composed of one type of atom cannot be decomposed into other substances. Represented by one or two letter symbol EX: copper wire (Cu), aluminum foil (Al)

Pure Substances - Molecules Molecule – a combination of 2 or more same atom that are covalently bonded. A molecule is the smallest particle of a substance which exhibits the physical and chemical characteristics of the substance. Diatomic molecules of elements : H2 O2 N2 Cl2 F2 I2 Br2

How are ELEMENTs represented? Molecule

Pure Substances - Compounds composed of two or more elements chemically combined in a fixed ratio properties differ from those of individual elements Represented by a chemical formula EX: water (H2O) table salt (NaCl)

Pure Substances - Compounds For example… Two different compounds, each has a definite composition.

Pure Substances - Compounds Compounds a compound of 2 or more different elements bonded together in a fixed proportion. H2O CO2 CaSO4 HBR Na2O KOH H2 CO3

How are COMPOUNDs represented?

Laws for Compounds Law of Definite Composition A given compound always contains the same, fixed ratio of elements. Law of Multiple Proportions Elements can combine in different ratios to form different compounds.

Pure Substances - Compounds Slight differences in combinations of atoms can have large difference in properties H2O - water H2O2 – hydrogen peroxide C2 H6O – ethanol, drinkable C2 H6O2 – ethylene glycol, poisonous

Pure Substances Same kind of particles throughout Compounds Can be decomposed into simpler substances by chemical changes, always in a definite ration Elements Cannot be decomposed into simpler substances by chemical changes

Let’s Look at Mixtures

Mixtures Mixtures are two or more substances that are physically combined. Mixtures do not have a fixed composition Mixtures do not have constant boiling points or melting points Variable composition Components retain their characteristic properties

Mixture May be separated into pure substances by physical methods Mixtures of different compositions may have widely different properties.

Mixtures Mixtures can be described by how uniform they are throughout. Heterogeneous Homogeneous

Mixtures - Heterogeneous Heterogeneous mixture Two or more phases (with same or different physical states) Each phase has different properties Not uniform throughout Examples: oil and water, sand and water, milk, fresh squeezed lemonade

Mixtures – Homogenous solution Homogenous mixture One phase – must always be the same Uniform throughout Same composition in a sample Examples: sugar, salt water, rubbing alcohol

Mixtures - Homogenous Alloys – combination of two or more metals Examples: brass and steel

How do we represent a MIXTURE? Two or more substances that are mixed together but are NOT chemically bonded.

Element, Compound or Mixture? Check for understanding Element, Compound or Mixture?

Element, Compound or Mixture?

Element, Compound or Mixture?

Element, Compound or Mixture?

Check for Understanding Number your papers from 1 to 15. Classify the following as an element, compound, or mixture (heterogeneous or homogeneous). Penny 6. Oxygen 11. Sea water Air 7. Sugar 12. Water Al foil 8. Chlorine gas 13. Graphite Windex 9. Salad dressing 14. Pepper Steel 10. Table salt 15. Paint

How did you do? 6. Oxygen – Element Penny – Mixture Homogenous (zinc and copper solids) Air - Mixture Homogenous (gases) Aluminum foil - Element Windex – Mixture Homogenous Steel – Mixture Homogenous (iron and carbon solids) 6. Oxygen – Element 7. Sugar – Compound (C6H12O6) 8. Chlorine Gas – Element

How did you do? 9. Salad Dressing - Mixture Heterogenous 10. Table salt – Compound (NaCl) 11. Sea water – Mixture Homogenous 12. Water – Compound 13. Graphite – Element (Carbon) 14. Pepper – Mixture - heterogeneous 15. Paint – Mixture - heterogeneous

Classifying Matter

Can it be physically separated? Matter Flowchart MATTER yes no Can it be physically separated? MIXTURE PURE SUBSTANCE Is the composition uniform? no yes Can it be chemically decomposed? no yes Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element Colloids Suspensions