Semester 1 Exam Review Key (PDF)

# Unit 0: Metric System and Measurement ## Key terms - **Mass:** The amount of matter in an object - **Control:** What would happen naturally during an experiment - **Constant**: What you keep the same in an experiment - **Independent variable:** What you change in an experiment - **Dependent vari...

# Unit 0: Metric System and Measurement ## Key terms - **Mass:** The amount of matter in an object - **Control:** What would happen naturally during an experiment - **Constant**: What you keep the same in an experiment - **Independent variable:** What you change in an experiment - **Dependent variable:** What you measure in an experiment ## Concepts - List the metric prefixes (in order!) | Prefix | Multiplier | |---|---| | Milli | 0.001 | | Centi | 0.01 | | Deci | 0.1 | | Base (g, L, m) | 1 | | Deka | 10 | | Hecto | 100 | | Kilo | 1000 | - 1000mg = 1g - 1L = 0.264 gal - 55 gal → 208.3 L - 3.5 kg → 3,500,000 mg ## Scientific Notation - .004892 → 4.892 x 10^-3 - 6.02x10^5 → 602,000 ## Decide if the statement in bold describes the: - Hypothesis - Independent variable - Dependent variable - Control - Constant - Conclusion **Experiment**: You are testing several types of perfume to see which one your friends like best. 1. **Control:** One day you don't wear any perfume at all. 2. **Constant:** While testing the different types, you spray the same amount on you each day. You take a shower and wash with the same soap and the same shampoo. You test the perfume by asking the same people how they like the perfume. 3. **Independent Variable:** Each day you spray a different kind of perfume on yourself. 4. **Dependent Variable:** Each day a different number of people like the perfume best. 5. **Conclusion:** At the end of the experiment, you decide based on your data, people prefer the first perfume the best. 6. **Hypothesis:** Before your experiment begins you state If I wear perfume, then people will like the smell. # Unit 1: Matter ## Key Terms - **Matter:** Anything that has mass and takes up space - **Density:** How close are particles packed together. Density = Mass / Volume - **Physical property:** A characteristic of a material, such as: Size, Color, or Shape. - **Physical change:** A change in size, shape, or state of matter - **Chemical property:** A characteristic of a substance and how it behaves. Ex. flammability - **Chemical change:** A change in a substance into a new substance - **Mixture:** A combination of two or more substances - physically - **Atom:** The smallest particle of an element that maintains its chemical + Physical prop. - **Element:** One type of atom with the same chemical physical properties - **Molecule/Compound:** A combination of two or more elements - chemically - **Homogeneous:** A uniform mixture of substances ex. Salt water - **Heterogeneous:** A non-uniform mixture of substances ex. Fruit Salad - **Solution:** A homogeneous mixture that remains constantly and uniformly mixed ## Concepts | State | Volume | Shape | How are the atoms situated? | |---|---|---|---| | Solid | Fixed/ changes | Fixed / changes | Really close / loose / far away| | Liquid | Fixed/ changes | Fixed / changes | Really close / loose / far away| | Gas | fixed/ changes | fixed / changes | Really close / loose / far away | - **Examples of a Chemical Property:** Solubility, flammability, reactivity - **Examples of a Chemical Change:** Fire, cooking - **Examples of a Physical Property:** Size, shape, color - **Examples of Physical Change:** Breaking, Melting **Solve density problems:** Find the mass of an item when its density = 3 g/cm³ and its volume = 4.5 cm³ - D = M/V - 3 = M/4.5 - M = 13.5g **What is the Law of Conservation of Mass? What does it mean?** - Mass is never created or destroyed. It only changes forms. # Unit 2: Atoms and the Periodic Table ## Key Terms | Type | Location | Charge | Mass | |---|---|---|---| | Proton | Nucleus | +1 | 1 | | Neutron | Nucleus | 0 | 1 | | Electron | Electron Cloud/ Orbits | -1 | ~0 | - **Valence electron:** electrons in the outermost shell. - **Nucleus:** Center of an atom contains protons + neutrons - **Atomic number:** Tells the number of protons & electrons in a neutral atom - **Mass number:** Represents the number of protons & neutrons in a nucleus - **Average atomic mass:** The average mass of all isotopes of an atom - **Ion:** An atom that has lost or gained electrons - **Isotope:** Atoms of the same element with different numbers of neutrons ## Concepts **What two properties are the same about a group of atoms (vertical column)** 1. # of Valence electrons. 2. Same chemical properties **Determine the number of protons, neutrons and electrons of an atom or ion** | Atom | Atomic Number | Mass Number | Protons | Neutrons | Electrons | Electron Dot Structure | |---|---|---|---|---|---|---| | O | 8 | 16 | 8 | 8 | 8 | O: | | Al | 13 | 27 | 13 | 14 | 13 | Al: | **Know the location and the basic properties of each of the following groups** - Alkali metal - Alkaline earth metal - 2 - Transition element - 3-12 - Non metals - Right Side - Halogens - 17 - Noble gasses - 18 - Semi-conductors - Stair-step **How did each scientist picture the atom to look?** - Dalton: Atomic Theory - Democritus: Atom - Thompson: Electron - Rutherford: Nucleus - Electron Cloud Model: Modern atomic theory **Father of the Periodic Table:** Mendeleev # Unit 3: Chemical Bonding ## Key Terms - **Covalent bond:** Bond forms between non-metals. They share electrons - **Ionic bond:** Bond forms between a metal & nonmetal. They give up or accept electrons - **Polyatomic ion:** An ion consisting of two or more atoms ## Concepts: - In H2SO4 there are (how many): 2 H atoms, 1 S atoms, and 4 O atoms - **Why do atoms bond?** To become stable, fill their Outer shell. **What do the roman numerals in a compound name indicate? Ex: Copper (II) sulfate** - The charge of the metal ion **Compare the melting points and boiling points of ionic compounds versus covalent compounds. Why does this happen?** - Ionic > Covalent in melting point, because Ionic bonds are stronger. **Name compounds from formulas** - KCI: Potassium Chloride - FeCl3: Iron (III) Chloride - CO2: Carbon Dioxide **Write formulas from compound names** - Aluminum bromide: AlBr3 - Diboron trioxide: B2O3 - Lead (IV) oxide PbO2 **Put the following elements together to form a complete compound AND draw the electron dot pictures of the compound.** **a. Ca + F** - Bond type: Ionic - Formula: CaF2 - Compound: Calcium Fluoride **b. H + N** - Bond type: Covalent - Formula: NH3 - Compound: Nitrogen trihydride **\* Prefixes are only used with \* Covalent bonds** # Unit 4: Chemical Reactions ## Key Terms - **Reaction:** A chemical change. - **Reactants:** What you have *before* a reaction takes place. - **Products:** What you have *after* a reaction takes place. - **Exothermic reaction:** Reaction releases heat - **Endothermic reaction:** Reaction absorbs heat - **Catalyst:** Speeds up reactions - **Inhibitor:** Slows down reactions ## Concepts **List 4 of the indicators of a chemical reaction** 1. A change in temperature. 2. Color Change 3. Bubbles 4. Precipitate formation **Name the 5 basic types of chemical reactions and an example of each.** 1. **Synthesis:** N2 + 3 H2 → 2 NH3 2. **Decomposition:** 2 S2O3 → 4 S + 3 O2 3. **Single Replacement:** 4 P + 5 O2 → 2 P2O5 4. **Double Replacement:** 5. **Combustion:** C2H4 + 3O2 → 2 CO2 + 2 H2O **Balance the following reactions** - a. N2 + 3 H2 → 2 NH3 - Reaction Type: Synthesis - b. 4 P + 5 O2 → 2 P2O5 - Reaction Type: Synthesis - c. C2H4 + 3 O2 → 2 CO2 + 2 H2O - Reaction Type: Combustion - d. 2 S2O3 → 4 S + 3 O2 - Reaction Type: Decomposition **What factors can change the rate of a reaction?** 1. Temperature. 2. Surface Area 3. Catalyst 4. Stirring / Agitation # Unit 5: Nuclear Chemistry ## Key Terms | Type | Greek Letter | Symbol | Composition | Charge | Stopped by | |---|---|---|---|---|---| | Alpha | α | ⁴₂He | 2 protons + 2 neutrons | +2 | paper, skin | | Beta | β | ⁰₋₁e | 1 electron | -1 | Aluminum Foil | | Gamma | γ | γ | EM Waves | 0 | Lead | - **Fission:** Large atoms breaking into smaller atoms - **Fusion:** Small atoms combining to form larger atoms - **Ionization:** Energy needed to add or remove electrons from an atom - **Half-life:** The time required for half of a substance to decay. ## Key Concepts 1. **The half-life of Americium-243 is 36 years. If a sample starts with 600 grams Americium-243, how much is left over after 180 years?** - #HL = 180 / 36 = 5 HL - 600(1/32) = 18.75g 2. **Write the equation for the alpha decay of Am-243** - ²⁴³₉₅Am → ⁴₂He + ²³⁹₉₃Np 3. **Write the equation for the beta decay of Cf-251** - ²⁵¹₉₈Cf → ⁰₋₁β + ²⁵¹₉₉Es 4. **What element does fission use? What element does fusion use?** - Fission: Uranium - Fusion: Hydrogen 5. **What are two things you can do to reduce your exposure to nuclear radiation?** - Not Smoke - Don't Fly