1. NJ ASK REVIEW P HYSICAL S CIENCE 8 th grade science

2. MATTER Matter – anything that has mass and takes up space Some types of matter are called Substance – Every form of matter contains both properties. substances A single kind of matter that is pure. physical and chemical *substances have the same type of make up and properties no matter where it comes from – Examples: Salt, sugar and water

3. P HYSICAL PROPERTIES A characteristic of a pure substance that can be observed without changing it to another substance. Physical properties can be observed by Examples of physical properties: touching or looking at a substance. Melting/freezing point Hardness Texture Color

4. C HEMICAL PROPERTIES A characteristic of a pure substance that describes its ability to change into different substances. Chemical properties can only be observed when Examples: a substance combines with something else and forms a new substance. Flammability Rusting

5. C HEMISTRY IS ALL ABOUT HOW MATTER CHANGES ! Physical Change - any change in the form or appearance of matter. A physical change change the substances Examples: DOES NOT chemical makeup Crushing Ripping Breaking Chopping Blending Dissolving

6. Chemical change - When one substance changes into one or more different substances Atoms are rearranged not taken away or added! Example: Keep in mind… during a chemical or physical change we call this C HEMISTRY IS ALL ABOUT HOW MATTER CHANGES ! Oxidation: rusting (this occurs when iron and oxygen mix) matter cannot be created or destroyed the law of conservation of mass

7. U NDERSTANDING CHEMICAL REACTIONS We know that a chemical change occurs when We can also call this a Chemical Reaction - one or more substances change into a new substance. chemical reaction A process in which atoms of one or more substances rearrange to form one or more new substances.

8. S IGNS OF A CHEMICAL REACTION

9. H OW CAN WE DESCRIBE A CHEMICAL REACTION ? By using Chemical equation - a description of a reaction using element symbols and chemical formulas. a chemical equation

10. PARTS OF A CHEMICAL EQUATION Reactant – Yield (or produces) – Product – Subscript – the starting substances in a chemical reaction (belong to the left of the arrow) the arrow used to represent the chemical reaction taking place. the substances produced by the chemical reaction (belong to the right of the arrow) Describes the number of elements in a compound. Belongs after the atom it represents and is written small. **If there is no subscript it means there is only one atom of that element**

11. L ABEL ALL PARTS OF THE FOLLOWING CHEMICAL EQUATION

12. C HEMICAL BONDS CONTAIN ENERGY Chemical bonds contain Some chemical reactions more energy than they absorb. Some chemical reactions more energy than they release. chemical energy release absorb

13. E NDOTHERMIC VS. EXOTHERMIC REACTIONS Endothermic Reaction – Exothermic Reaction - chemical reactions that absorb thermal energy. chemical reaction that releases thermal energy.

14. A FTER TALKING ABOUT ATOMS THAT ARE CHEMICALLY COMBINED … Chemical bonds Covalent bonds – A chemical bond formed when two atoms share electrons.

15. Ionic bonds - Atoms transfer (give or take) valence electrons to reach stability

16. H ETEROGENEOUS MIXTURE A mixture in which substances are not evenly mixed. Examples: Salad Granite Soil

17. H OMOGENEOUS MIXTURE A mixture in which two or more substances are evenly mixed on the atomic level but NOT bonded together. Examples: Another name for “homogeneous mixture” is Air Soda solution

19. M IXTURES CAN BE SEPARATED Mixtures can be separated because Mixtures can be separated by using physical methods including: Filtering Boiling Magnetism they are not bonded together separation by size separation by boiling point separation by magnetism (for objects attracted to magnets)

20. S UBSTANCE VS. MIXTURE

21. A CIDS AND BASES … NECESSITIES TO OUR EVERYDAY LIFE ! The pH scale is used to measure how and a substance is. The pH scale is a range of values from to. ACIDIC BASIC 014

22. P H SCALE Something that is neither acidic or basic is Neutral is the pH of: Any value below the pH of 7 is: Any value above the pH of 7 is: **Label the pH scale on your paper** NEUTRAL 7 (water) ACIDIC BASIC

23. ACIDS Chemicals in which the positive ion is a hydrogen atom Ion – an atom or group of atoms that has a positive or negative charge Properties Tastes sour Reacts with metals Reacts with carbonates – (causes bubbles to appear) Turns litmus paper red **Litmus is a colored chemical which can change from red to blue and back again – the color it changes depends on whether the substance is basic or acidic. Corrosive – (eats away other materials)

24. BASES Substances with a negative ion called Hydroxide Properties: Tastes bitter Slippery Turns litmus paper blue

25. FROM EXPERIENCE NAME SOME ACIDS AND BASES: ACIDSBASES pH = O pH = 2 pH = 3 pH = 4 NEUTRAL pH = 8-9 pH = 10 pH = 12 pH = 14

26. P H SCALE The pH scale expresses the concentration of ions in a solution. Low pH tells you: High pH tells you: HYDROGEN THERE IS A HIGH CONCETNRATION OF HYDROGEN IONS. THERE IS A LOW CONCETNRATION OF HYDROGEN IONS.

27. BEING SAFE In order to handle acids and bases safely you need to know theirand Concentration – A reaction between an acid and a base is called: Neutralization - pHCONCENTRATION The amount of one material in certain volume of another material. NEUTRALIZATION A reaction of an acid with a base creating a solution that is no longer as acidic or basic as the original solution.