Lecture Notes: Atomic Structure and Chemical Bonds

Introduction

• Overview of exam one practice exam for chemistry.
• Focus on atomic structure, chemical bonds, and isotopes.

Atomic Structure

Subatomic Particles

• Protons: Positive charge, determine the element.
• Neutrons: No charge, affect the isotope.
• Electrons: Negative charge, affect reactivity.

Atoms and Ions

• Atoms are electrically neutral when protons = electrons.
• Ions: Formed by changing the number of electrons.
• Isotopes: Formed by changing the number of neutrons.

Atomic Number and Mass

• Atomic Number: Number of protons in an atom, determines the element.
• Atomic Mass: Total number of protons and neutrons.
• Atomic Weight: Average mass of all isotopes of an element.

Chemical Bonds

Types of Bonds

• Covalent Bonds: Sharing of electrons between atoms.
  • Polar Covalent Bonds: Unequal sharing (e.g., water).
  • Non-Polar Covalent Bonds: Equal sharing (e.g., O2, H2).
• Ionic Bonds: Transfer of electrons between atoms (e.g., NaCl).

Bond Properties

• Electronegativity: Tendency of an atom to attract shared electrons.
• Hydrogen Bonds: Weak bonds between polar molecules, responsible for water's unique properties.
• Van der Waals Forces: Weakest interactions between molecules.

Elements in Biological Systems

• Most common elements: Hydrogen, Carbon, Oxygen, Nitrogen.
• Properties: Low atomic mass, not necessarily full outer shells.

Chemical Reactions and Interactions

• Hydrogen Bonds in Water: Responsible for cohesion and surface tension.
• Like Dissolves Like: Polar substances dissolve in polar solvents; non-polar in non-polar.

Practice Problems and Concepts

Distinguishing Elements and Isotopes

• Different elements have different numbers of protons.
• Isotopes have the same number of protons but different neutrons.

Ionic and Covalent Characteristics

• Formation of ions and ionic bonds from electron transfer.
• Formation of covalent bonds from electron sharing.

Exam Preparation Tips

• Understand concept relationships (e.g., subatomic particles' roles, bond types).
• Practice calculations for atomic mass and isotopes.
• Familiarize with periodic table layout (atomic number, weight).

Key Takeaways

• Protons determine element identity; neutrons affect isotope.
• Electrons influence chemical behavior and bond formation.
• Polar and non-polar covalent bonds defined by electronegativity.
• Water's properties largely due to hydrogen bonding.

Conclusion

• Thorough understanding of atomic structure and chemical bonds foundational for chemistry.
• Review key concepts and practice problems for a comprehensive understanding.