10 Week Science Study Guide Grade 8

1. Lab safety rules Follow directions Never eat or drink in lab Wear safety goggles Don’t fool around in the lab Ask if you are sure about something

2. Steps of scientific method State a problem Gather information State a hypothesis Experiment Data and results conclusion

3. Hypothesis A logical guess or prediction about something in science (educated guess)

4. Units of measurement Mass (grams) Volume of solid (cm3) Volume of liquid (ml) or (liter) Length of a cube (cm) Distance from Whitesboro to NYC (km)

5. Mass and weight Mass is the amount of stuff in an object and it cannot change Weight is the pull of gravity and can change

6. MASS Amount of matter or stuff in an object Measured with a triple beam balance Grams

7- 9 VOLUME Amount of space an object takes up Measured with a graduated cylinder for liquid volumes V = LxWxH using a ruler for regular sided objects (cm3)

10 - 11 Phases of matter Phase of matter Shape Volume solid No change liquid Changes gas

12. Phases of matter Phase change Includes these phases Evaporation Liquid to gas Freezing Liquid to solid Melting Solid to liquid Sublimation Solid to gas Condensation Gas to liquid

13 & 14 Phases of matter Particles move fastest with a gas and slowest with a solid When objects are heated the particles move fastest and when they get cooled down, particle motion slows down

15. PERIODIC TABLE Mendeleev – developed 1st periodic table of elements Organized in order of atomic mass

16. PERIODIC TABLE Horizontal Rows – called Periods There are 7 Elements have no common characteristics

16. PERIODIC TABLE Vertical Columns – called groups or families There are 18 Elements have common characteristics

17. STRUCTURE OF THE ATOM NUCLEUS – center of the atom Protons: positive Neutrons: neutral ELECTRON CLOUD – surrounds nucleus Electrons: negative

18. PERIODIC TABLE Atomic Mass: protons plus neutrons (actual mass of element) Atomic Number: tells number of protons or electrons

19. Electron counts in each energy level Level 1: 2 electrons Level 2: 8 electrons Level 3: 8 electrons Level 4: 8 electrons

20. Mass number This number comes from the total proton and total neutrons found in the nucleus added together

21. ISOTOPES Atoms of the same element with different numbers of neutrons

22,25,26,30. Families on periodic table Can be determined by group number! Group #1 = 1 valence electron (alkali metals) very reactive Group #2 = 2 valence electrons (alkaline metals) Group #3-12 = 3 valence electrons (transition metals) Group # 13 = 3 valence electrons (boron ) Group # 14 = 4 valence electrons (carbon) Group #15 = 5 valence electrons (nitrogen) Group # 16 = 6 valence electrons (oxygen) Group # 17 = 7 valence electrons (halogens) very reactive Group #18 = 8 valence electrons (noble gases) not reactive

23 & 24THE ZIG-ZAG LINE LEFT = metals RIGHT = nonmetals Malleable – can be formed into thin sheets Ductile – can be formed into wires Have luster Conducts electricity and heat RIGHT = nonmetals Brittle Dull Nonconductors of heat and electricity

27 – 29 DENSITY Amount of mass in a given volume D = m/V Density of water is 1.0 g/mL Objects float if they are less dense than water Density never changes unless you change the material