Chemistry

• The electrons in an element are arranged in a specific sequence in spherical "shells" around the nucleus.
• Atoms have different electron configurations based on their atomic number (number of protons).
• Each shell can hold up to two electrons, with the first shell holding only one pair of electrons.
• Metals, nonmetals, metalloids, gases, and noble gases are the major groups of elements based on their properties.
• Elements are organized in the periodic table according to their atomic number, electron configurations, and chemical properties.
• Hydrogen bonds are weak electrostatic attractions between a hydrogen atom bonded to a highly electronegative atom and another electronegative atom.
• Chemical reactions involve the breaking and forming of chemical bonds.
• Ionic bonding occurs when metals lose electrons to non-metals, forming positive ions and negative ions that attract each other due to electrostatic forces.
• Covalent bonds form between non-metal elements through sharing of valence electrons.
• Metallic bonding is responsible for the unique properties of metals such as high melting points, ductility, malleability, electrical conductivity, thermal conductivity, reflectance, and luster.