Chemistry Lecture Notes Review

Key Concepts in Chemistry

• Visible Spectrum Wavelengths

  • Longest: Red

  • Shortest: Violet

• Atomic Line Spectra Formation

  • Electrons absorb energy, jump to higher energy levels, then release light when falling back, creating specific wavelengths (colors).

• Periodic Trends

  • Atomic Radius: Decrease across a period, increase down a group.

  • Ionization Energy: Increase across a period, decrease down a group.

  • Electronegativity: Increase across a period, decrease down a group.

• Cation vs Anion Sizes

  • Cation: Formed by losing electrons, size decreases.

  • Anion: Formed by gaining electrons, size increases.

• Periodic Table Arrangement

  • Arranged by increasing atomic number, grouped by similar properties.

• Valence Electrons by Group

  • Alkali Metals: 1 valence electron, form +1 ions.

  • Alkaline Earth Metals: 2 valence electrons, form +2 ions.

  • Oxygen Group: 6 valence electrons, form -2 ions.

  • Halogens: 7 valence electrons, gain 1 electron.

  • Noble Gases: 8 valence electrons, stable.

• Bonding Concepts

  • Valence electrons are in the outermost shell.

  • Ionic Bonding: Atoms lose or gain electrons to achieve noble gas configuration.

  • Covalent Bonding: Atoms share electrons.

• Properties of Compounds

  • Ionic Compounds: High melting/boiling points, conduct electricity when dissolved in water, forms crystal lattice structures.

  • Covalent Molecules: Lower melting/boiling points, typically non-conductive, can exist in all states at room temperature.

• Lewis Structures

  • Used to visualize molecular bonding and polarity.

• Empirical Formula

  • Represents the simplest ratio of elements in a compound.