CHEMISTRY FIRST SEMESTER REVIEW

Physical or Chemical? Tearing paper P Growing grass C Salt dissolving in water P Ice cube melting P Iron rusting C Burning wood C Evaporation P Milk souring C Fruit spoiling C Glue in glue gun melting P Silver ring turning your finger green C Distilling alcohol from water P Photosynthesis C Leaf turning colors C

List 3 signs of a chemical reaction Bubbling Change in color/smell Change in temperature Precipitate (when a solid forms from 2 liquids)

Chemical or Physical Property? Boiling P Reactivity C Burning P Cooking C Texture P Color P Rusting C

SI = metric system What is the metric base unit for… Length Meter Mass Gram Volume liter

DENSITY What is the density of a rock if it has a mass of 32 grams and a volume of 8 mL? 4 g/mL (don’t forget the units!) What is the density of a book with a mass of 2 kg and a volume of 130 cm 3? 0.02 kg/cm 3 What is the volume of the liquid that has a mass of 48 g and a density of 3 g/mL ? 16 g/mL What is the mass of an object that has a volume of 15 cm 3 and a density of 4 g/cm 3 ? 60 g

Without the marble, the water level is at 20.0 mL. When you drop the marble, the water level rises to 28.0 mL. What is the volume of the marble? 8 mL This method is called water displacement.

IDENTIFY EACH EQUATION AS BEING SYNTHESIS, DECOMPOSITION, COMBUSTION, SINGLE REPLACEMENT, DOUBLE REPLACEMENT 2SO 2 + O 2 → 2SO 3 S, C Al (SO 4 ) 3 + 3Ca(OH) 2 → 2Al(OH) 3 + 3CaSO 4 DR Mg + 2AgNO 3 → Mg(NO 3 ) 2 + 2Ag SR 2Be + O 2 → 2BeO S,C 2Al + 3CuSO 4 → Al 2 (SO4) 3 + 3Cu SR 2PbO 2 → 2PbO + O 2 D

INTENSIVE OR EXTENSIVE? MASS extensive LENGTH Extensive COLOR Intensive DENSITY intensive DUCTILITY Intensive VOLUME extensive MELTING /BOILING POINT Intensive

Give the number of protons, neutrons and electrons for the following isotopes. Br-79 has ___ p, ___n and ___e 35, 44, 35 Br- 81 has ____ p, ___n and ___e 35, 46, 35

Fill in the blanks All the mass of an atom is found in the ___. nucleus In a neutral atom, the number of protons = the number of ____. electrons The subatomic particle that identifies an element is the ____. Proton Write the isotopic symbol for the element that has 40 protons and 92 neutrons Zr

What 2 particles are found in the nucleus? Protons, neutrons What is the overall charge of the nucleus? positive Where is most of an atom’s mass found? Nucleus What element has 10 neutrons and 11 electrons? Flourine

INDEPENDENT AND DEPENDENT VARIABLES How does the temperature of a lake change with depth? Give the IV and DV. IV= different depths of lake (in meters) DV = temperatures that you measure (°C ) Control variables: same lake, same location Does heating a cup of water allow it to dissolve more sugar? IV = temperature of the water DV = amount of sugar that dissolves Control variables: same amount of water

RADIATION The energy released in a nuclear reaction comes from ___. Protons and neutrons Give the symbol for each particle- Alpha 4 2 He Beta 0 -1 e Gamma 0 0 ᵞ

Nuclear Equations Complete the equation: Rn→ Pb + ___ 4 2 He Write the equation: Sodium-24 emits a beta particle Na → 0 -1 e Mg

HALF-LIFE PROBLEMS The half-life of Sb-115 is 30 minutes. How much of a 80 g sample will remain at the end of 2 hours (120 minutes)? 0 → 30 min → 60 min → 90 min → 120 min 80 g → 40 g → 20 g → 10 g → 5 g U-235 has a half-life of 710,000,000 years. How many half-lives have passed after 2,130,000,000 years? What percent of the original U-235 would remain? 0 → 710,000,000 →1,420,000,000 →2,130,000,000 0 → 1 half-life → 2 half-lives → 3 half-lives 1 → ½ → ¼ → 1/8