Atoms and Subatomic Particles

Atoms

Protons

• Positively charged subatomic particles
• Found in the nucleus of an atom
• Number of protons determines the element of an atom (atomic number)
• Protons have a mass of approximately 1 atomic mass unit (amu)

Neutrons

• Neutral subatomic particles
• Found in the nucleus of an atom
• Number of neutrons determines the isotope of an element
• Neutrons have a mass of approximately 1 amu

Electrons

• Negatively charged subatomic particles
• Found in the electron cloud surrounding the nucleus
• Number of electrons is equal to the number of protons in a neutral atom
• Electrons have a negligible mass compared to protons and neutrons

Nuclear Reactions

• Reactions involving changes to the nucleus of an atom
• Types of nuclear reactions:
  • Radioactive decay: spontaneous emission of radiation from an unstable nucleus
  • Fission: splitting of a heavy nucleus into two or more lighter nuclei
  • Fusion: combination of two or more light nuclei into a heavier nucleus

Atomic Structure

• The nucleus is surrounded by an electron cloud
• Electron cloud is divided into energy levels or shells
• Each energy level can hold a specific number of electrons
• Electrons in the outermost energy level are called valence electrons

Chemical Bonds

• Formed when atoms share or exchange electrons to achieve a stable electron configuration
• Types of chemical bonds:
  • Ionic bonds: formed when electrons are transferred between atoms
  • Covalent bonds: formed when electrons are shared between atoms
  • Hydrogen bonds: weak bonds between atoms with a hydrogen atom bonded to a highly electronegative atom
  • Metallic bonds: formed when electrons are delocalized in a metal lattice

Atoms

Subatomic Particles

• Protons are positively charged and found in the nucleus, with a mass of approximately 1 amu.
• Neutrons are neutral and found in the nucleus, with a mass of approximately 1 amu.
• Electrons are negatively charged and found in the electron cloud, with a negligible mass.

Atomic Number and Isotopes

• The number of protons determines the element of an atom (atomic number).
• The number of neutrons determines the isotope of an element.

Electron Cloud

• The electron cloud is divided into energy levels or shells.
• Each energy level can hold a specific number of electrons.
• Valence electrons are electrons in the outermost energy level.

Nuclear Reactions

• Radioactive decay is the spontaneous emission of radiation from an unstable nucleus.
• Fission is the splitting of a heavy nucleus into two or more lighter nuclei.
• Fusion is the combination of two or more light nuclei into a heavier nucleus.

Chemical Bonds

• Ionic bonds are formed when electrons are transferred between atoms.
• Covalent bonds are formed when electrons are shared between atoms.
• Hydrogen bonds are weak bonds between atoms with a hydrogen atom bonded to a highly electronegative atom.
• Metallic bonds are formed when electrons are delocalized in a metal lattice.