States of Matter and Atomic Structure

States Of Matter

• Four fundamental states of matter:
  • Solid: rigid, fixed shape and volume
  • Liquid: takes shape of container, fixed volume
  • Gas: takes shape and volume of container
  • Plasma: high-energy state, ionized gas
• Phase transitions:
  • Melting: solid to liquid
  • Freezing: liquid to solid
  • Vaporization: liquid to gas
  • Condensation: gas to liquid
  • Sublimation: solid to gas
  • Deposition: gas to solid

Atomic Structure

• Atomic model:
  • Proton (positive charge) in nucleus
  • Neutron (no charge) in nucleus
  • Electron (negative charge) in electron cloud
• Atomic components:
  • Protons: determine atomic number (identity of element)
  • Neutrons: determine atomic mass (isotopes)
  • Electrons: determine chemical properties
• Electron configuration:
  • Valence electrons: outermost energy level, participate in bonding
  • Core electrons: inner energy levels, do not participate in bonding

Molecular Bonds

• Types of bonds:
  • Ionic bond: electrostatic attraction between oppositely charged ions
  • Covalent bond: sharing of electrons between atoms
  • Hydrogen bond: weak attraction between hydrogen and electronegative atoms
• Bonding theories:
  • Electronegativity: measure of an atom's ability to attract electrons
  • Polarity: unequal sharing of electrons, resulting in partial charges
• Molecular shape and polarity:
  • VSEPR theory: predicts molecular shape based on electron pair repulsion
  • Molecular polarity: results from unequal sharing of electrons

Chemical Reactions

• Types of reactions:
  • Synthesis: two or more substances combine to form a new compound
  • Decomposition: a single compound breaks down into two or more substances
  • Replacement (single displacement): one element replaces another in a compound
  • Combustion: reaction involving oxygen, often resulting in heat and light
• Chemical equations:
  • Reactants: substances present at the start of a reaction
  • Products: substances formed during a reaction
  • Stoichiometry: study of quantitative relationships in chemical reactions

Periodic Table

• Organization:
  • Elements arranged by atomic number (number of protons)
  • Periods: horizontal rows, represent energy levels
  • Groups: vertical columns, represent similar chemical properties
• Periodic trends:
  • Atomic radius: decreases from left to right, increases from top to bottom
  • Electronegativity: increases from left to right, decreases from top to bottom
  • Ionization energy: increases from left to right, decreases from top to bottom

States Of Matter

• Solid state: rigid, fixed shape and volume
• Liquid state: takes shape of container, fixed volume
• Gas state: takes shape and volume of container
• Plasma state: high-energy state, ionized gas
• Phase transitions occur between these states, including:
  • Melting: solid to liquid
  • Freezing: liquid to solid
  • Vaporization: liquid to gas
  • Condensation: gas to liquid
  • Sublimation: solid to gas
  • Deposition: gas to solid

Atomic Structure

• Atomic model consists of:
  • Proton (positive charge) in nucleus
  • Neutron (no charge) in nucleus
  • Electron (negative charge) in electron cloud
• Atomic components have specific roles:
  • Protons determine atomic number (identity of element)
  • Neutrons determine atomic mass (isotopes)
  • Electrons determine chemical properties
• Electron configuration is crucial:
  • Valence electrons: outermost energy level, participate in bonding
  • Core electrons: inner energy levels, do not participate in bonding

Molecular Bonds

• Types of bonds form between atoms:
  • Ionic bond: electrostatic attraction between oppositely charged ions
  • Covalent bond: sharing of electrons between atoms
  • Hydrogen bond: weak attraction between hydrogen and electronegative atoms
• Bonding theories explain bond formation:
  • Electronegativity: measure of an atom's ability to attract electrons
  • Polarity: unequal sharing of electrons, resulting in partial charges
• Molecular shape and polarity are influenced by:
  • VSEPR theory: predicts molecular shape based on electron pair repulsion
  • Molecular polarity: results from unequal sharing of electrons

Chemical Reactions

• Types of reactions occur:
  • Synthesis: two or more substances combine to form a new compound
  • Decomposition: a single compound breaks down into two or more substances
  • Replacement (single displacement): one element replaces another in a compound
  • Combustion: reaction involving oxygen, often resulting in heat and light
• Chemical equations represent reactions:
  • Reactants: substances present at the start of a reaction
  • Products: substances formed during a reaction
  • Stoichiometry: study of quantitative relationships in chemical reactions

Periodic Table

• Organization of the periodic table is based on:
  • Atomic number (number of protons)
  • Periods: horizontal rows, represent energy levels
  • Groups: vertical columns, represent similar chemical properties
• Periodic trends are observed:
  • Atomic radius: decreases from left to right, increases from top to bottom
  • Electronegativity: increases from left to right, decreases from top to bottom
  • Ionization energy: increases from left to right, decreases from top to bottom

Learn about the four fundamental states of matter, phase transitions, and atomic structure, including the atomic model and its components.