What are Molecules?

What are Molecules?

• A molecule is formed when two or more atoms combine and become chemically bonded.
• Atoms are the most basic unit of matter and can't be divided into anything smaller.
• Molecules serve as the building blocks that make up everything in the world, living and nonliving.

Living Organisms

• To be considered a living organism, there are eight criteria that must be met:
  • Growth and development
  • Evolution
  • Response to the environment
  • Comprised of cells
  • Reproduction
  • Genetic code
  • Homeostasis
  • Obtaining and using energy

Molecular Size

• Molecules range from shapes to sizes, making it hard to determine how big they are.
• The size of a molecule can be measured using nanometers, angstroms, or molecular weight.
• Molecular weight is the mass sum of all atoms present within a molecule.

Interpreting the Periodic Table

• The periodic table shows the atomic mass of each element underneath the atomic symbol.
• Molecular weight can be calculated using the atomic masses of the atoms present in the molecule.

Types of Molecules

• Homonuclear Diatomic molecules are the bonding of two identical atoms.
• Heteronuclear Diatomic atoms are the binding of two different atoms.
• Examples of homonuclear diatomic molecules include O2, H2, N2, F2, I2, Cl2, and Br2.
• Examples of heteronuclear diatomic molecules include NaCl, HCl, CO, and NO.

Most Common Molecule in Living Things

• Water is the most abundant molecule in the body, making up about 65% of its total mass.
• The most common elements making up the elements of the body are carbon, nitrogen, hydrogen, oxygen, and sulfur.
• Combinations of these elements form the macromolecules in our body: proteins, lipids, carbohydrates, and nucleic acids.