Physical science final Scientific Method

Vocabulary

  • Chemical Reaction: A process in which a substance transforms into new and different products or substances.

  • Reactants: The original substances or raw materials that participate in a chemical reaction.

  • Products: The new substances formed as a result of a chemical reaction.

  • Aqueous: Refers to a substance that is dissolved in water or can be dissolved in water.

  • Precipitate: A solid that forms from a solution during a chemical reaction.

Examples of Chemical Changes

  • Burning Paper: An example of a chemical change where paper transforms into ash, smoke, and gases.

  • Baking a Cake: A process that involves a series of chemical reactions resulting in a new product (the cake).

  • Iron rusting

Law of Conservation of Mass

  • Definition: The principle stating that mass is neither created nor destroyed in a chemical reaction.

  • Connection to Reactants and Products: The mass of the starting materials (reactants) must equal the mass of the new substances (products) formed at the end of the chemical reaction.

Balancing Chemical Reactions

  • Changeable: Coefficients (the large numbers in front of chemical formulas) can be changed to balance a reaction.

  • Unchangeable: Subscripts (the small numbers at the bottom right of chemical symbols) cannot be altered without changing the substance.

Evidence of Chemical Reactions

  • Indicators that a chemical reaction has occurred include:

    • Color Change: Observable alteration in color.

    • Gas Production: Bubbles or gases forming.

    • Precipitate Formation: Solid developing in a solution.

    • New Odor: A change in smell.

    • Change in Temperature: The reaction either absorbs or releases heat.

    • Emission of Light: Light being produced during the reaction.

Types of Chemical Reactions

  1. Synthesis Reaction: Combining two or more substances to form a new compound.

  2. Decomposition Reaction: Breaking down a compound into simpler substances.

  3. Single Replacement Reaction: One element replaces another in a compound.

  4. Double Replacement Reaction: Two compounds exchange components to form two new compounds.

  5. Combustion Reaction: A substance reacts with oxygen, often producing heat and light.

Scientific Method Steps

  1. Observation: Using the senses to gather knowledge.

  2. Research: Gathering background information related to the observation.

  3. Hypothesis: A proposed explanation that is often testable.

  4. Experiment: Testing the hypothesis through controlled methods.

  5. Data Analysis: Interpreting the results collected during the experiment.

  6. Conclusion: Summarizing findings based on the experiment and data analysis.

Scientific Concepts

  • Hypothesis: An educated guess that does not need to be testable.

  • Scientific Theory: An explanation for why natural phenomena occur.

  • Scientific Law: A statement describing a principle that consistently occurs under certain conditions.

Control Group vs. Constant

  • Constant: A variable that remains unchanged throughout an experiment.

  • Control Group: A baseline group that is used for comparison during an experiment.

Measurement Precision

  • Example of Precision: A weight of 213.75 lbs is more precise than measurements of 198.7 lbs and 115 lbs.

Data Representation

  • Pie Charts: Visual representations used to show percentages of a whole.

Quantitative vs. Qualitative Data

  • Quantitative Data: Numerical data expressing quantities (e.g., five, six, or seven).

  • Qualitative Data: Descriptive data providing characteristics (e.g., green fur).

Elements, Compounds, and Mixtures

  • Element: A substance composed of only one type of atom.

  • Compound: A substance formed from two or more elements that are chemically combined.

  • Mixtures: Combinations where substances retain their individual properties and do not chemically combine.

  • Solution: A homogeneous mixture formed when one substance is dissolved in another.

Periodic Table Trends

  • Valence Electrons: The number of valence electrons increases by one from left to right across the periodic table.

  • Atom Behavior: Atoms tend to gain or lose electrons to achieve stability.

  • Magnesium Atom Composition: 12 protons, 12 neutrons, and 12 electrons.

  • Energy Levels: Electrons can transition to higher energy levels by absorbing specific amounts of energy.

  • Transition Metals: Located in groups three through twelve of the periodic table.

  • Atomic Number Trend: The atomic number increases as one moves from left to right across the periodic table.

Chemical Formulas

  • Subscripts: Indicate the number of atoms of each element in a molecule, placed at the bottom right of a symbol.

  • Coefficients: Large numbers placed in front of the chemical formulas to indicate the number of molecules.

Chemical Equations

  • Reactants undergo change to form products.

  • Arrow: Indicates the transformation from reactants to products in a chemical equation.

Chemical Reaction and Mass Conservation

  • Rearrangement of Mass: The law of conservation of mass emphasizes that no mass is created or destroyed; it is rearranged during chemical processes.

  • Balanced Chemical Equations: To determine if a chemical equation is balanced, ensure the number of atoms on both sides is equal.

Charged Atoms

  • Losing Electrons: An atom that loses electrons becomes positively charged.

  • Gaining Electrons: An atom that gains electrons becomes negatively charged.