Unit 1: “Matter and Change”

1. Unit 1: “Matter and Change”

2. Matter • Matter is anything that: a) has mass, and b) takes up space • Mass = a measure of the amount of “stuff” (or material) the object contains (don’t confuse this with weight, a measure of gravity) • Volume = a measure of the space occupied by the object

3. Properties are… • Words that describe matter (adjectives) • Physical Properties- a property that can be observed and measured without changing the material’s composition. • Examples- color, hardness, m.p., b.p. • Chemical Properties- a property that can only be observed by changing the composition of the material. • Examples- ability to burn, decompose, ferment, react with, etc.

4. States of Matter Result of aTemperatureIncrease? Definite Volume? Definite Shape? Will it Compress? Small Expans. Solid YES YES NO Small Expans. Liquid NO NO YES Large Expans. Gas NO NO YES

5. Three Main Phases

6. Physical vs. Chemical Change • Physical change will change the visible appearance, without changing the composition of the material. • Boil, melt, cut, bend, split, crack • Is boiled water still water? • Can be reversible, or irreversible • Chemical change - a change where a new form of matter is formed. • Rust, burn, decompose, ferment

7. Chemical Change A change in which one or more substances are converted into different substances. Heat and light are often evidence of a chemical change.

8. Recognizing Chemical Changes • Energy is absorbed or released (temperature changes hotter or colder) • Color unexpected color changes • Gas production (bubbling, fizzing, or odor change; smoke) • Formation of aprecipitate- a solid that separates from solution (won’t dissolve) • Irreversibility- not easily reversed But, there are examples of these that are not chemical – boiling water bubbles, etc.

9. Conservation of Mass • During any chemical reaction, the mass of the products is always equal to the mass of the reactants. • All the mass can be accounted for: • Burning of wood results in products that appear to have less mass as ashes; where is the rest? • Law of conservation of mass

10. 43.43 g Original mass = 43.43 g Final mass reactants = product

11. Measurement

12. Over time people realized there were differences in the way people made measurements

14. Accuracy and Precision

15. Measurements Accuracy and Precision Some measurements are not very accurate.

16. Measurements Accuracy and Precision Some measurements can be very precise and accurate.

17. Measurements Accuracy and Precision Measurements can only be as precise and accurate as the instrument that produced it.

18. Measurements Accuracy and Precision How many numbers can we use for these scales?

19. Measurement Rules

20. Measurements Measurement Rules All non-zero digits are significant.

21. Measurements Measurement Rules Zeros between significant digits are always significant.

22. Measurements Measurement Rules Trailing zeros in a number are only significant if there is a decimal point somewhere in the number.

23. Measurements Measurement Rules Zeros in the beginning of a number are place holders and are not significant.

24. Measurements Measurement Rules Zeros following a number after a decimal are significant.

25. Math operations and measurement

26. Measurements Math Operations When adding or subtracting use the least number of decimal places.

27. Measurements Math Operations When multiplying or dividing use the least total number of sig. figs. to find your answer.

28. Measurements Math Operations Scientific notation is taking a number and putting it into a certain form.