Untitled Quiz

Molecular Compounds and State Changes

• Pure molecular compound: Water (H₂O)
• Melting point: 0.0 °C; Boiling point: 100.0 °C
• Visualization of molecular structures shows changes at different temperatures.

Physical vs. Chemical Changes

• Identification of changes to a substance (Substance X) under a microscope.
• Distinctions between possible physical changes and chemical changes must be made.

Pure Substances Classification

• Classification of sketches of substances as elements, compounds, or mixtures based on microscopic views.

Significant Digits

• Important to count significant digits in measurements for accuracy.
• Examples:
  • 0.003000 J (4 significant digits)
  • 2.1 x 10^-3 mL (2 significant digits)
  • -9.0 x 10^-2 kJ/mol (3 significant digits)
  • 94600. kg (5 significant digits)

Rounding and Scientific Notation

• Rounding measurements to 3 significant digits (e.g., 0023.43 g to 23.4 g).
• Conversion of scientific notation:
  • 7.977 x 10^-2 = 0.07977
  • 0.004209 = 4.209 x 10^-3

Calculations in Scientific Notation

• Multiplication example: (2.3 x 10^-3) * (-3.0 x 10^-2) = -6.9 x 10^-5.

Density, Mass, and Volume

• Use of sketches to deduce mass, volume, and density for objects in specific scenarios.

Composition of Substances

• Classification of pure substances as either elements or compounds based on atomic structure.

Chemical Formulas

• Ammonium carbonate (NH₄)₂CO₃ contains 8 hydrogen atoms.
• Given molecules:
  • SOCl₂ (sulfur dichloride)
  • C₂H₄O₂ (acetic acid)

Electric Charge and Atomic Structure

• The net electric charge of a neutral object is 0.
• Calcium (Ca) has 20 protons and 20 electrons.

Periodic Table Information

• Sodium (Na) is located in Period 3, Group 1A.
• Periods = horizontal rows, Groups = vertical columns.
• Aluminum (Al) belongs to Period 3, Group 3A.
• Elements in Period 2, Group 2A include Beryllium (Be).
• Lanthanum (La) has 57 protons and electrons.

Element Families

• Bromine and Lithium belong to specific element families (e.g., Halogens and Alkali Metals).

Electron Configuration

• Electron configuration for magnesium and phosphorus to illustrate electron distribution.

Valence Electrons

• Aluminum has 3 valence electrons; Xenon (Xe) has 8 valence electrons.
• Valence elections can be deduced from the group the element occupies.

Chemical Symbols and Formulas

• Symbols for elements in various periods/groups must be written correctly.
• Complete chemical formulas should include physical state symbols (s, l, g, aq).

Ionic and Molecular Compounds

• Classification of compounds as ionic or molecular based on their properties.
• Empirical formulas should be provided for binary ionic compounds formed from given ions.

Cationic and Anionic Symbols

• Knowledge of ionic species symbols is essential for writing compound formulas.

Compound Formation

• Determine whether pairs of elements form ionic compounds; if so, provide empirical formulas and names.