The periodic table is an arrangement of the chemical elements ordered by their atomic number, electron configuration, and recurring chemical properties. It consists of rows (periods) and columns (groups). Elements in the same group have similar properties due to their similar valence electron configurations.
The periodic table is divided into three main categories:
Periodic trends are regular variations in elemental properties with increasing atomic number. Some key trends include:
Valence electrons, the electrons in the outermost shell of an atom, determine an element's reactivity and bonding behavior. Elements with similar valence electron configurations tend to have similar chemical properties.
Chemical bonding is the attraction between atoms that allows the formation of chemical substances. The three main types of chemical bonds are:
Ionic bonds form when electrons are transferred from one atom to another, creating oppositely charged ions that attract each other. These bonds typically form between metals and nonmetals.
Covalent bonds form when electrons are shared between atoms. The shared electrons are attracted to the nuclei of both atoms, holding the atoms together. Covalent bonds can be single, double, or triple depending on the number of shared electron pairs. They can also be polar (unequal sharing) or nonpolar (equal sharing).
Metallic bonds form between metal atoms. In a metallic solid, valence electrons are delocalized and shared among all the metal atoms, creating a "sea of electrons" that holds the positively charged metal ions together.
Lewis dot structures are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist. The VSEPR (Valence Shell Electron Pair Repulsion) theory is used to predict the geometry of molecules based on the number of electron pairs around the central atom.
Practice exercises for this week's lesson will be provided in a separate file.