Basic Chemistry Concepts

Basic Chemistry Concepts

• Chemistry is the study of substances, their composition, structure, properties, and reactions.
• Substances have consistent composition and properties.
• Light, heat, energy, sound, magnetism, and reflection are not considered chemicals.
• Matter is anything that has mass and occupies space.
• Matter is made of atoms.
• Atoms are the basic building blocks of matter.
• When two or more atoms bond, they form molecules.
• The arrangement of atoms/molecules dictates the physical property of the matter.
• Matter can be classified as a solid, liquid, or gas.
• A solid has a fixed volume and shape; its particles are closely packed together and vibrate but don't move around.
• A liquid has a fixed volume but takes on the shape of its container; its particles are loosely packed and can move past each other.
• A gas has neither a fixed volume nor a fixed shape and expands to fill its container; its particles are very far apart and move freely.

Scientific Method

• The scientific method is an empirical approach to understanding nature through observation and experimentation.
• Key characteristics include:
  • Observations: noting and recording natural phenomenons (AKA data)
  • Formulation of hypotheses: tentative explanations based on reason and evidence. Must be falsifiable (possible to prove wrong).
  • Experimentation: procedures to test hypotheses and gather more data.
  • Formulation of conclusions and theories: well-established hypotheses forming the basis of scientific theories. Theories explain why a natural phenomenon occurs and are validated by experimental results.
• A scientific law is a brief statement that summarizes past observations and predicts future ones. It does not explain why an event occurs, but rather states that a certain relationship exists.

Scientific Measurement

• Scientific data can be
• Qualifiable: observational and subjective (e.g., blue car)
• Quantifiable: measurable and objective (e.g., 538 ml of water) using standardized units.
• Units: needed to specify measurements. Most will have a unit.
• The metric system and SI system are commonly used.
  • SI (International System of Units) is based on the metric system and uses units like meters (m), kilograms (kg), seconds (s), Kelvin (K), etc,.
  • The metric system uses units like centimeters (cm), liters (L), and grams (g).
• Measured numbers: numbers obtained by using measuring tools,
• Length is measured in meters (m) or centimeters (cm).
• Volume is measured in liters (L) or milliliters (mL).
• Mass is measured in kilograms (kg) or grams (g).
• Temperature is measured in Celsius (°C) or Kelvin (K); conversion equations exist between Celsius and Fahrenheit (°F)
• Time is measured in seconds (s).

Significant Figures

• Significant figures in a measurement are all the certain digits plus the estimated one.
• Nonzero numbers are significant.
• Zeros between nonzero digits are significant.
• Zeros at the end of a decimal number are significant.
• Zeros used as placeholders in large numbers are not significant.
• Exact numbers (obtained by counting or definitions) have unlimited significant figures.

Scientific Notation

• Scientific notation is used for very large or very small numbers.
• It consists of a coefficient (1-10) and a power of 10.
• The power of 10 represents the number of places the decimal point has been moved.

Units of Measurement

• Units are critical to specify measurements.
• Various units represent different quantities.
• Equivalencies are used to convert between different units.

Density

• Density is the mass of a substance per unit volume (mass/volume).
• Density is a physical property used to describe a substance.
• Common units include: (g/cm³), (g/mL), or (g/L).
• Greater densities mean particles are tightly packed together.
• Substances can be identified based on their densities.

Physical Properties

• Physical properties are characteristics that can be observed or measured without changing the chemical identity of a substance.
• Examples include: shape, color, odor, melting point, boiling point, density and physical state.

Physical Changes

• Physical changes occur when a substance changes its physical state or appearance, but its chemical composition remains the same.
• Examples include: melting, boiling, freezing, dissolving, crushing, etc.

Chemical Properties

• Chemical properties describe a substance’s ability to react with other substances or undergo chemical changes to form new substances.

Chemical Changes

• Chemical changes occur when a substance transforms into a new substance (or substances) having different chemical and physical properties.
• Examples include: burning, rusting, cooking, digesting, etc

Atoms

• Atoms are the basic building blocks of matter.
• Atoms are too small to be seen with the naked eye.
• They consist of a nucleus and orbiting electrons.
• The nucleus contains protons and neutrons.

Atomic Number

• The atomic number is the number of protons in an atom and is specific to each element.
• It is listed on the periodic table above the elemental symbol.

Mass Number

• The mass number represents the total number of protons and neutrons within an atom's nucleus.
• It is not displayed on the periodic table.

Isotopes

• Isotopes are atoms of the same element that have different mass numbers.
• This means they have the same number of protons, but different numbers of neutrons.
• Isotopes are useful for identifying specific atoms of an element.

This quiz covers fundamental concepts of chemistry, including the definitions of matter, atoms, and molecules. It explains the different states of matter and their properties. Test your understanding of these essential topics in chemistry.