Warm-up

1. Warm-up • What instrument would you use to measure temperature? • Which of the following is a unit of volume? a. gram b. atmosphere c. meter d. liter • What property of matter can you measure using a graduated cylinder? Thermometer Volume

2. Classifying Matter • Classify pure substances as elements and compounds. • Describe the characteristics of an element and the symbols used to identify elements. • Distinguish pure substances from mixtures. • Classify mixtures as heterogeneous or homogeneous. • Classify mixtures as solutions, suspensions, or colloids.

3. Matter? • What is matter? • Anything that has mass and takes up space • Why do we need to classify matter? • Not all matter is the same. • Different types of matter must be treated differently. • Example • Not all clothes are made of the same fabric. • Clothes require different washing techniques.

4. Matter Classification Matter Pure Substances Mixtures Elements Compounds Homogeneous Heterogeneous

5. Pure Substances • Made up of all the same thing or one type of matter. • Pure substances have the same properties regardless of sample. • Either compounds or elements

6. Elements • Substances that cannot be broken down into simpler substances. • Think of atoms. • Contain only one type of atom. • It has a fixed composition • Ingredients can’t change. • Identified by symbol • Examples of elements: • Aluminum (Al), Gold (Au), Carbon (C) - solids • Bromine (Br2), Mercury (Hg) - liquids • Oxygen (O2), Nitrogen (N2) - gases

7. Compounds • Substances that are made up of two or more simpler substances that can be broken down. • They are combined in chemically defined ratios. • H2O – Water, C6H12O6 – Glucose (Sugar). • The elements have different properties when alone. • Hydrogen and Oxygen are flammable as elements. • But water is not flammable. • Identified by formula

8. Mixtures • The make-up of mixtures are not fixed. • Properties vary by mixture contents. • They retain some of the properties of the individual substances. • Sand is an example of mixture. • One could find sand from many different beaches but all could have a very different make up. • Mixtures can be classified by how well the parts of the mixture are distributed throughout it.

9. Heterogeneous Mixtures • The Greek words hetero and genus meaning “different” and “kind.” • Two or more types of atoms, physically combined in no definite ratio. • Different throughout.

10. Homogeneous Mixtures • Two or more substances, physically combined in no definite ratio. • Same throughout. • Must be a SOLUTION • A solute dissolved in a solvent.

11. Measuring the volume of liquids • Liquids have volume. We measure that volume with a graduated cylinder. • Notice the meniscus in the graduated cylinder. • Always measure at the bottom of the meniscus! • A liquid in any container has a meniscus. • Liters (L) and mL (milliliters) are most often used to express the volume of liquids.

12. Solid Volume • If each side in the cube below is 2m, what is the volume of the cube? __________ • The volume in a solid is always expressed in cubic units. • Cubic means having “three dimensions.” • Cubic meters(m3) or cubic centimeters(cm3) are most often used to express the volume of a solid. • The 3 in m3 signifies that three quantities were used to get the final result. (That is a derived quantity!)

13. The Volume of Solids, Liquids, and Gases • 1 mL = 1 cm3 REMEMBER THAT! • That is why you can compare the volume in liquids to solids. • How do you measure the volume of a gas? • You can’t see, so how do you measure it? ex: balloon _________________________

14. Measuring Weight and Mass • The SI unit for mass is kilogram (kg). • Sometimes we will use milligrams or grams. (mg or g) • The SI unit for weight (or gravitational force) is NEWTONS. • A Newton is approximately equal to the weight of a 100 gram mass on earth.

15. The major differences between • WEIGHT • A measure of the gravitational force on an object. • Varies depending on where the object is in relation to the earth. Example: ____________ • Measured with a spring scale. • Expressed in Newtons. • MASS • A measure of the amount of matter in object. • Always constant, no matter the location. • Measured with a balance. • Expressed in kilograms, grams, and milligrams.

16. Describing Matter • Knowing the characteristics or properties of an object can help you identify the object. • There are: • Physical Properties • Chemical Properties

17. Physical Properties • Things that describe the object are physical properties. • Physical properties can also be observed or measured without changing the identity of the matter. • Examples of physical properties include: color, odor, size, state, density, solubility, melting point, etc…

18. Spotlight on Density • Density is a very helpful physical property. • Density = mass per unit of volume or Density = mass/volume • Density is an excellent help in identifying substances because each substance has its own density.

19. Chemical Properties • Chemical properties describe a substance based on its ability to change into a new substance with different properties. • Ex: wood burns to form ash and smoke • Chemical properties cannot be observed with your senses. • Chemical properties aren’t as easy to observe as physical properties. • Examples of chemical properties: flammability and reactivity

20. Characteristic Properties • The properties that are most useful in identifying a substance are its characteristic properties. • Remember the difference between physical and chemical properties. • Physical properties can be observed! (with your eyes!) IDENTITY OF SUBSTANCE DOES NOT CHANGE! • You can observe chemical properties only in situations in which the identity of the substance could change.

21. Physical Changes • A physical change is a change that affects one or more physical properties of a substance. • Physical changes do not form new substances! EX: ice melting or sugar dissolving • Physical changes are easy to undo.

22. Chemical Changes • A chemical change occurs when one or more substances are changed into entirely new substances with different properties. • You can observe chemical properties only when a chemical change might occur! • Examples of chem. changes: baking a cake rusting

23. Clues to chemical changes • Color change • Fizzing or bubbling (gas production) • Heat • Production of light, sound, or odor. • Chemical changes are not usually reversible!