Exploring Atoms and Molecules

Subatomic Particles

• Electrons are negatively charged subatomic particles found in the outer regions of an atom.
• The nucleus, located at the center of an atom, contains positively charged protons and neutral neutrons.

Ions

• Ions are atoms or molecules that have gained or lost one or more electrons, resulting in a net electric charge.
• Cations are positively charged ions (lost electrons), while anions are negatively charged ions (gained electrons).

Molecules

• Molecules are formed when two or more atoms chemically bond together, representing the smallest unit of a chemical compound.
• They can consist of the same type of atoms (e.g., O2) or different types (e.g., H2O).

Composition of an Atom

• An atom is primarily composed of a nucleus (containing protons and neutrons) surrounded by electron shells where electrons reside.
• This structure determines the chemical properties and behavior of elements.

Charge of an Electron

• An electron carries a negative charge, typically denoted as -1 elementary charge.

Charge of the Nucleus

• The nucleus of an atom is positively charged due to the presence of protons, which outweigh the neutral charge of neutrons.

Properties of Solids

• In solids, particles are closely packed in a fixed arrangement and vibrate minimally, providing a definite shape and volume.

Extensive Properties

• Extensive properties depend on the amount of matter present, such as mass and volume, differing from intensive properties, which remain constant regardless of the sample size.